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CONSTRUCTIVE KNOWLEDGE, PROBABLE CAUSE,
AND ADMINISTRATIVE DECISIONMAKING
Simon Stern*
I
NTRODUCTION
The last quarter century has witnessed the quiet and largely
unnoticed development of a doctrine that could significantly change
the meaning of probable cause. Traditionally, probable cause has
been based on the knowledge of someone who had enough informa-
tion to form a belief about the suspect’s guilt, but this new doctrine
looks to constructive knowledge, not actual knowledge, so that no one
involved in the investigation need actually be capable of forming such
a belief. The result is that an officer acting on nothing more than the
“inarticulate hunches” disparaged in Terry v. Ohio
1
might nevertheless
be treated as having enough information to justify a search or arrest.
For example, in United States v. Gillette,
2
a recent Eighth Circuit
decision, the court relied on this doctrine to validate the search of a
pickup truck by an officer who had responded to a call for backup but
who had not been given any instruction to search; rather, he “simply
arrived on the scene and immediately began to search vehicles.”
3
Probable cause for the search of Gillette’s pickup was lacking, and he
2007 Simon Stern. Individuals and nonprofit institutions may reproduce and
distribute copies of this Article in any format, at or below cost, for educational
purposes, so long as each copy identifies the author, provides a citation to the Notre
Dame Law Review, and includes this provision and copyright notice.
* Climenko Fellow and Lecturer on Law, Harvard Law School. Thanks to Bill
Eskridge, Jack Goldsmith, Judge Ronald M. Gould, Bruce Hay, Elena Kagan, Yale
Kamisar, Jody Madeira, Dan Meltzer, Alexandra Michel, Wes Oliver, Frank Pasquale,
John Townsend Rich, Bill Rubenstein, Joe Singer, Eric Sonnenschein, Carol Steiker,
Matthew Stephenson, Bill Stuntz, James Sullivan, and Virginia Vander Jagt.
1 392 U.S. 1, 22 (1968).
2 245 F.3d 1032, 1034 (8th Cir. 2001), cert. denied, 584 U.S. 982 (2001). Thanks
to Stephen C. Moss of the Kansas City Federal Defender’s Office for providing a copy
of the petition for certiorari.
3Id.
1085
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1086 notre dame law review [vol. 82:3
had not consented to the search.
4
However, the truck was in the
driveway of a house whose inhabitant had consented to a search of his
vehicle. The court reasoned that the search would have been valid if
performed by either of the officers who had obtained the inhabitant’s
consent, because it would have been based on a reasonable, if errone-
ous, belief.
5
Because the third officer was answering a call for backup,
there had been sufficient “communication between him and the
officers on the scene to make him a member of their team and thus to
impute to him [their] knowledge,”
6
and so he was entitled to the same
assessment of reasonableness for any belief based on that knowledge.
The rule at work in Gillette extends—and significantly revises—a
well-established and uncontroversial imputation doctrine, the collec-
tive-knowledge rule.
7
That rule allows for the imputation of knowl-
edge between officers when one officer, having acquired probable
cause, instructs another to conduct a search or arrest and does not
explain why. The rule gives constructive knowledge a procedural role,
but bases the substantive analysis of probable cause on the actual
knowledge of the officer who issued the instruction. The new rule, on
the other hand, gives constructive knowledge a substantive role in the
evaluation of probable cause. Courts have not differentiated between
the two rules, but in what follows, I reserve the term “collective-knowl-
edge rule” for the conventional version and refer to the new variant as
the “constructive-knowledge rule.”
Both rules have arisen in the context of warrantless police con-
duct. In the typical constructive-knowledge case, several officers are
investigating a crime, none personally has probable cause, one of
them conducts a search or arrest anyway, and the court lets in the
evidence on the theory that the officers knew enough in the aggregate
to support probable cause.
8
Gillette is unusual in two respects. First,
the acting officer had not personally acquired any incriminating infor-
4 Gillette was convicted of conspiracy to manufacture methamphetamine, and in
describing the evidence of his participation, the court pointed to the evidence found
in the vehicle and “Mr. Gillette’s admission . . . that he knew that the lab was in his
truck.” Id. at 1033. The admission, however, came only after Gillette was arrested
(“Mr. Gillette was given his Miranda warnings . . . before he made his admission,” id.
at 1034), and so it could not have created probable cause for the search. The court
cited nothing else to suggest that the police had any basis for searching Gillette’s
truck.
5Id. at 1033–34.
6Id. at 1034.
7Id.
8 For a useful overview on both collective- and constructive-knowledge cases,
treated under the rubric of “collective knowledge,” see 2
W
AYNE
R. L
A
F
AVE
, S
EARCH
AND
S
EIZURE
§ 3.5(c) (4th ed. 2004).
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2007] constructive knowledge 1087
mation. Second, there was another officer present who, taken alone,
could legally have conducted the search on the basis of his reasonable
belief. Thus, Gillette does not illustrate the aggregation process that
usually occurs in constructive-knowledge cases, when each officer has
a little information but none of them has enough. On the other
hand, Gillette shows that the doctrine may extend even to officers who
have no information and who have received no instruction. Gillette
also helps to show the fuzziness at the limits of the collective-knowl-
edge doctrine, which has usually been cabined to cases in which
officers are “working closely together” on an investigation.
9
In Gillette,
the officers’ communication went no further than the backup call—
when the third one arrived, he “immediately began to search” instead
of talking to his colleagues—and they were not in close physical prox-
imity.
10
If the only requirement is that each officer must somehow be
deputed a “member of the team,” the rule’s implications are far-reach-
ing indeed.
Probable cause requires “a reasonable ground for belief of
guilt.”
11
If the “reasonable ground” depends on constructive knowl-
edge, that knowledge, in turn, may support a purely constructive
belief—a belief that no officer could justifiably have held, because no
officer, taken alone, knew enough to arrive at that conclusion. And
when knowledge and belief are constructive, those two preconditions
may generate probable cause which itself is purely constructive, which
is deemed to exist only by virtue of a hindsight perspective that inac-
curately gauges the strength of the evidence and misdescribes the con-
clusions that the officers would have reached if they had conferred in
advance.
What goal does the constructive-knowledge rule serve? In the
context of corporate criminal liability, courts have said that employ-
ees’ knowledge may be aggregated to show that a corporation “knew”
the sum of that information, even if the employees did not communi-
cate with each other.
12
By treating the corporation as if it had that
knowledge, and by imposing criminal liability accordingly, the law cre-
ates an incentive for the corporation to establish centralized informa-
tion structures that will allow the managers to minimize subordinates’
9Gillette, 245 F.3d at 1035 (Alsop, J., dissenting) (quoting United States v.
O’Connell, 841 F.2d 1408, 1419 (8th Cir. 1988)). For further discussion of the vari-
ous ways in which the courts have described the preconditions for applying the con-
structive-knowledge rule, see infra notes 97–104 and accompanying text.
R
10 Gillette, 245 F.3d at 1034 (majority opinion).
11 Maryland v. Pringle, 540 U.S. 366, 371 (2003).
12 See, e.g., Thomas A. Hagemann & Joseph Grinstein, The Mythology of Aggregate
Corporate Knowledge: A Deconstruction, 65
G
EO
. W
ASH
. L. R
EV
.
210, 212–17 (1997).
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1088 notre dame law review [vol. 82:3
criminal behavior. Belief has little importance in this context. That
no single corporate actor has organized the information so as to be
aware of any harmful conduct does not mean that none is occurring.
It makes sense to force the corporation to take preventive steps, even
if the cost of developing a formal coordination mechanism is
significant.
Fourth Amendment law is not an area that abounds in formali-
ties. All kinds of searches and arrests can be conducted without a war-
rant or any other explanation that commits the police in advance to
some particular description of the state of their knowledge and the
basis for their action. And with good reason—time devoted to record-
ing what an officer believes and why he believes it would be time taken
away from the investigation. Further, if the justification had to be for-
malized in advance, then a hastily recorded detail, entered inaccu-
rately, could jeopardize the whole enterprise when it came to be
reviewed in court. The proliferation of exceptions to the warrant
requirement might even lead one to conclude that we abhor Fourth
Amendment formalities and seek to reduce them. When the officers’
knowledge is dispersed and fragmented, however, there are good rea-
sons for requiring enough formality to unify that information. When
officers are “working closely together,” the time and resources needed
to exchange information are insignificant, but the value of that
exchange is enormous. A reasonable belief is the requirement that
brings probable cause into being. If grounds for probable cause can
be assembled after the fact, then on some occasions the police may
decide to act first in the hope of finding support later. A formal
requirement that the police confer in advance would cement the basis
for probable cause, and might also produce additional arrests in cases
where no officer believed she had seen enough to justify that step.
More than half of the federal circuits have adopted some version
of the constructive-knowledge rule, but they have not agreed about its
limits.
13
Moreover, because it appears to have arisen through a misin-
terpretation of the collective-knowledge rule, and has so far been
treated as an instance of that rule, there has been little effort to articu-
late an independent rationale for this new doctrine. In what follows, I
address its origins, status, and implications. Part I discusses the devel-
opment of the collective-knowledge rule and the rise of its new vari-
13 See, e.g., Burrell v. McIlroy, 423 F.3d 1121 (9th Cir. 2005); United States v.
Cook, 277 F.2d 82 (1st Cir. 2002); United States v. Colon, 250 F.3d 130 (2d Cir. 2001);
United States v. Sawyer, 224 F.3d 675 (7th Cir. 2000); United States v. Kye Soo Lee,
962 F.2d 430 (5th Cir. 1992); United States v. Kapperman, 764 F.2d 786 (11th Cir.
1985); United States v. Wright, 641 F.2d 602 (8th Cir. 1981).
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2007] constructive knowledge 1089
ant. The constructive-knowledge rule might be taken to depend on
an “inevitable discovery” theory as its tacit premise. On that view,
when the sum of each separate officer’s information is sufficient for
probable cause, their knowledge should be aggregated because it
would soon have been shared in any case. Part II reviews that argu-
ment’s merits and limits, and concludes that it does not provide a
satisfactory justification for the new rule.
Part III turns to administrative law for another perspective on
joint decisionmaking. It might appear that the constructive-knowl-
edge rule raises no novel concerns because imputation is a basic and
routine aspect of all probable-cause analysis. “‘Subjective intentions
play no role in ordinary, probable cause Fourth Amendment analy-
sis,’”
14
and so even when an officer acts alone, the court imputes her
basis for a search or arrest, asking not what she actually thought but
whether “‘the circumstances, viewed objectively, justify [her]
action.’”
15
What distinguishes the constructive-knowledge rule is that
it treats the police as having conferred, and therefore credits them
with having engaged in the kind of formal process of information-
sharing that corporations are encouraged to conduct. Questions
about the need to share information, to deliberate, and to articulate
the rationale for an action loom large in judicial review of administra-
tive decisionmaking, and this perspective provides additional reasons
for questioning the premises of the constructive-knowledge rule.
Finally, I conclude in Part IV by reflecting briefly on the implications
of this discussion for the probable-cause calculus.
I. C
OLLECTIVE
K
NOWLEDGE AND
C
ONSTRUCTIVE
K
NOWLEDGE
The collective-knowledge rule, the new rule’s precursor, gained
currency in the 1960s as an agency theory permitting an officer to
instruct another to undertake a search or arrest.
16
The collective-
knowledge rule focuses on the facts known by the first officer at the
time of the instruction: those facts are imputed to the acting officer,
so that one officer’s actual knowledge becomes another’s constructive
knowledge, and probable cause is evaluated accordingly. Since the
1980s, however, the imputation rule has taken on a life of its own, as
courts have begun to use the doctrine to permit searches and arrests
14 Ohio v. Robinette, 519 U.S. 33, 38 (1996) (quoting Whren v. United States,
517 U.S. 806, 813 (1996)).
15 Id. (quoting Whren, 517 U.S. at 813).
16 See, e.g., Williams v. United States, 308 F.2d 326, 327 (D.C. Cir. 1962). In some
jurisdictions the rule is known as the fellow-officer rule. See, e.g., Michalik v. Her-
mann, 422 F.3d 252, 260 n.7 (5th Cir. 2005).
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1090 notre dame law review [vol. 82:3
when there is no instruction and no officer has probable cause.
Under this new, supercharged version of the rule, which has been
adopted in various forms by more than half of the federal circuits,
probable cause may be analyzed by considering the aggregate knowl-
edge of all officers “work[ing] together on an investigation.”
17
The traditional collective-knowledge rule is a relatively costless
way of increasing a police department’s efficiency. The rule allows
police departments to delegate functions, deploy personnel, and
exploit communications technology fully, instead of engaging in a
burdensome duplication of tasks that would impede law enforcement.
Once a member of the department has developed probable cause,
others are qualified to use the end-product without being required to
retrace the process first.
The rule frees up personnel so that the department can devote
more time to information-gathering, can issue more directions to
arrest at roll calls and via “be on the lookout” (BOLO) broadcasts,
and can use the same number of officers to search for more suspects.
By enhancing the portability of probable cause as a public good, the
collective-knowledge rule decreases the cost of policing and affords
the public more protection for the same price—and the rule pro-
duces this effect without diminishing the protections afforded by the
probable-cause standard itself, because it applies only to instructions
that are already supported by probable cause.
18
The collective-knowledge rule thus conforms to a familiar pattern
in Fourth Amendment doctrine. In general, the Supreme Court will
approve any measure that allows law enforcement to gather evidence
faster and more cheaply if the Court can persuade itself that the short-
cut does not erode the probable-cause standard. More precisely, the
Court holds law enforcement to the least demanding requirement
that would apply to any actor seeking lawfully to perform the same
17 United States v. Terry, 400 F.3d 575, 581 (8th Cir. 2005); see also People v.
Ramirez, 70 Cal. Rptr. 2d 341, 344 (Cal. Ct. App. 1997) (“[W]hen police officers work
together to build ‘collective knowledge’ . . . the important question is not what each
officer knew . . . but how valid and reasonable the probable cause was that developed
in the officers’ collective knowledge.”); People v. Hardaway, 718 N.E.2d 682, 691 (Ill.
App. Ct. 1999) (“Probable cause may be established by facts within the collective
knowledge of police officers working together to investigate a crime even if those facts
are not within the personal knowledge of the arresting officer.”).
18 See, e.g., State v. Soldahl, 15 P.3d 564, 568 (Or. 2000) (“The collective knowl-
edge doctrine in no way undermines the probable cause requirement. The doctrine
merely views law enforcement agencies as a unit. As a unit, officers may direct one
another to carry out lawful police activities. However, the state retains the obligation
at trial to establish that police action was initiated by an officer who had . . . probable
cause.”).
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2007] constructive knowledge 1091
action for any reason and (in the case of a governmental actor) trying
reasonably to respect the suspect’s Fourth Amendment interests. The
Court has stated many times that the probable-cause standard does
not vary according to the offense, but requires a similar showing of
proof in all cases, to help maintain the steady equilibrium produced
by the Fourth Amendment’s “accommodation of public and private
interests.”
19
But while the standard may impose a fixed cost on the
public regardless of the crime under investigation, the ease or diffi-
culty of meeting the standard varies according to how strictly the law
constrains the options available to the police when gathering informa-
tion to establish probable cause.
The Supreme Court tends to reject rules that would make it eas-
ier and cheaper to gather such information (and hence to establish
probable cause), if the Court perceives those rules as promoting law
enforcement interests at the expense of individual privacy, unsettling
the balance struck by the Fourth Amendment. Therefore the courts
have (largely) preserved the warrant requirement for searches of
homes,
20
and, while permitting suspicionless searches in some limited
contexts, have refused to allow the police to undertake such searches
for “ordinary crime control.”
21
19 Illinois v. Gates, 462 U.S. 213, 239 (1983); see also
A
LAN
F. W
ESTIN
, P
RIVACY AND
F
REEDOM
67 (1967) (“When the American Republic was founded, the framers estab-
lished a libertarian equilibrium among the competing values of privacy, disclosure,
and surveillance.”), quoted in Tracey Maclin, Katz , Kyllo, and Technology: Virtual Fourth
Amendment Protection in the Twenty-First Century, 72 M
ISS
. L.J. 51, 51 (2002); William J.
Stuntz, O.J. Simpson, Bill Clinton, and the Transsubstantive Fourth Amendment, 114
H
ARV
.
L. R
EV
. 842, 869–76 (2001) (discussing the constancy of the probable-cause standard
regardless of the offense). But see Myron W. Orfield, Jr., Deterrence, Perjury, and the
Heater Factor: An Exclusionary Rule in the Chicago Criminal Courts, 63
U. C
OLO
. L. R
EV
. 75,
100–15 (1992) (discussing perjury by police to fabricate probable cause, thereby dis-
rupting the equilibrium created by the Fourth Amendment).
20 See, e.g., Georgia v. Randolph, 126 S. Ct. 1515, 1528 (2006); Kyllo v. United
States, 533 U.S. 27, 31–33 (2001). But see New York v. Harris, 495 U.S. 14, 18 (1990).
21 City of Indianapolis v. Edmond, 531 U.S. 32, 44 (2000). The Court in Edmond
noted that the “special needs” exception, allowing for search without probable cause
or reasonable suspicion, could not be used to permit vehicle stops at checkpoints to
search for narcotics: “[W]e [do] not credit the ‘general interest in crime control’ as
justification for a regime of suspicionless stops,” id. at 41 (quoting Delaware v. Prouse,
440 U.S. 648, 659 n.18 (1979)). Thus, given that “the primary purpose of the . . .
checkpoint program is to uncover evidence of ordinary criminal wrongdoing, the pro-
gram contravenes the Fourth Amendment.” If the police could throw up “roadblocks
designed primarily to serve the general interest in crime control, the Fourth Amend-
ment would do little to prevent such intrusions from becoming a routine part of
American life.” Id. at 41–42.
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1092 notre dame law review [vol. 82:3
Conversely, when the Court takes the view that a rule would lower
the cost of establishing probable cause without giving the police a free
hand to regulate the public as they choose, by stopping, searching,
and arresting citizens without sufficient cause, the Court has approved
that rule. Thus, in addition to approving the collective-knowledge
rule, which easily satisfies this requirement, the Court has also held
that the police may try to develop probable cause by looking through
a suspect’s trash,
22
or by stopping suspects on a pretext (so long as
there is support for the pretextual justification),
23
and that evidence
gathered pursuant to a warrant is admissible in court so long as any
lack of probable cause was not completely obvious on the face of the
warrant.
24
In all of these instances, the Court has either taken the
view that there is no search at all (in the case of trash on the curb)
25
or that the police are acting under constraint, and not according to
their own lights, insofar as they are required to meet an objective stan-
dard that would justify the decision to stop a suspect
26
or to proceed
on a warrant.
27
But it is not clear that procedural constraints on information-
gathering may be relaxed in these ways without affecting the balance
between policing and privacy. Many of the disputes over recent
changes in Fourth Amendment law have turned on disagreements
about procedures that some have supported as lowering the cost of
information-gathering, but that others have opposed as destructive of
the people’s right to be free from invasive searches.
28
The constructive-knowledge rule raises just this problem. It
diminishes the cost of information-gathering (though not signifi-
cantly), because the rule makes it unnecessary for officers to share
22 California v. Greenwood, 486 U.S. 35, 37–40 (1988).
23 See Whren v. United States, 517 U.S. 806, 811–13 (1996); see also Devenpeck v.
Alford, 543 U.S. 146, 153 (2004) (“[The police officer’s] subjective reason for making
the arrest need not be the criminal offense as to which the known facts provide proba-
ble cause.”).
24 See United States v. Leon, 468 U.S. 897, 923 (1984).
25 See Greenwood, 486 U.S. at 39–44.
26 See Whren, 517 U.S. at 817–18.
27 See Leon, 468 U.S. at 923.
28 Compare, e.g., Greenwood, 486 U.S. at 40–41 (holding that no search occurred,
and hence neither probable cause nor reasonable suspicion was required for police to
retrieve suspect’s trash, left on the curb, and noting that “the police cannot reasona-
bly be expected to avert their eyes from evidence of criminal activity that could have
been observed by any member of the public”), with id. at 46 (Brennan, J., dissenting)
(“[M]embers of our society will be shocked to learn that the Court, the ultimate guar-
antor of liberty, deems unreasonable our expectation that the aspects of our private
lives that are concealed safely in a trash bag will not become public.”).
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2007] constructive knowledge 1093
their information so long as they collectively know enough to satisfy
the probable-cause standard. But unlike its precursor, the construc-
tive-knowledge rule alters the Fourth Amendment balance and may
weaken the probable-cause standard. Traditional doctrine requires
that probable cause must be analyzed from “‘the standpoint of an
objectively reasonable police officer,’”
29
but as already noted, under
the new rule the analysis may hinge on a purely constructive belief;
thus the “objectively reasonable” assessment may be one that no
officer was actually capable of forming. That alteration is significant
because probable cause may depend not only on knowing certain facts
about the suspect, but also on understanding why those facts, taken
together, are incriminating—particularly when they might not be
incriminating if viewed separately.
30
Moreover, because it foils the
application of the exclusionary rule, the constructive-knowledge rule
creates the risk, at least in some circumstances, that police officers
may make an arrest knowing that they lack probable cause, but believ-
ing that other officers will likely have information that renders the
arrest permissible.
Courts adopting the constructive-knowledge rule have rarely
stopped to explain why unshared knowledge may be aggregated.
These courts generally purport to be applying the collective-knowl-
edge rule in its traditional form, and even when they acknowledge
that they are not merely imputing information by means of an instruc-
tion, the courts do not articulate any clear rationale for this extension
of the rule. Why this silence? The simplest explanation is that in its
traditional form, the collective-knowledge rule uses very broad lan-
guage which, though applied restrictively, might be misunderstood to
permit imputation of knowledge without any communication between
officers.
Additionally, though no court has said as much, the rule might in
some instances be rationalized by analogy to “inevitable discovery”—
another rule that lowers the cost of information-gathering, arguably at
29 Maryland v. Pringle, 540 U.S. 366, 371 (2003) (quoting Ornelas v. United
States, 517 U.S. 690, 695 (1996)).
30 See, e.g., United States v. Sokolow, 490 U.S. 1, 9–10 (1989) (noting that deten-
tion was permissible even though “[a]ny one of [the relevant] factors is not by itself
proof of any illegal conduct and is quite consistent with innocent travel [and] ‘inno-
cent behavior will frequently provide the basis for a showing of probable cause’”
(quoting Illinois v. Gates, 462 U.S. 213, 243 n.13 (1983))); United States v. Woodrum,
202 F.3d 1, 7 (1st Cir. 2000) (“[A] combination of independently innocent behaviors
and circumstances . . . can create reasonable suspicion in certain cases.”).
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1094 notre dame law review [vol. 82:3
the expense of individual privacy.
31
Just as information collected dur-
ing an illegal search may be admitted into evidence on the ground
that it would inevitably have been obtained during a permissible
search that the police were going to initiate, a search or arrest on
insufficient cause might be regarded as a mere error in timing, under
the theory that all of the officers present at the scene would soon have
shared their observations, providing sufficient cause for the chal-
lenged action. This Part discusses the rise of the collective-knowledge
rule and the spin-off of the constructive-knowledge rule. The next
Part turns to the question of “inevitable discovery.”
A. The Development of the Collective-Knowledge Rule
The collective-knowledge rule was created some forty years ago to
serve an agency function. When an officer sends out a message depu-
tizing others to act for him, the recipients are treated as standing in
his shoes and sharing his knowledge, and so the validity of the arrest
31 See Nix v. Williams, 467 U.S. 431, 444 (1984) (“If the prosecution can establish
by a preponderance of the evidence that the information ultimately or inevitably
would have been discovered by lawful means . . . then . . . the evidence should be
received [rather then being suppressed under the exclusionary rule].”). For further
discussion, see infra Part II.
The collective-knowledge doctrine for corporate criminal liability offers another
possible explanation for the courts’ transformation of the Fourth Amendment collec-
tive-knowledge rule into a constructive-knowledge rule. As discussed at supra note 12
R
and accompanying text, the corporate doctrine aggregates all employees’ knowledge,
whether or not it was shared with others, to make the corporation criminally liable if
it “knew” that it was acting illegally. See United States v. Bank of New England, 821
F.2d 844, 856 (1st Cir. 1987). The corporate doctrine and its Fourth Amendment
counterpart are similar, but the former was created to force corporations to structure
communication among employees so that they would be aware of potential illegal
conduct and would act to prevent it, whereas the Fourth Amendment rule lacks any
such normative justification. See generally
R
ICHARD
S. G
RUNER
, C
ORPORATE
C
RIMINAL
L
IABILITY AND
P
REVENTION
§ 4.01 (2006) (“[Collective liability based on aggregate
knowledge] will help to ensure that employees in one corporate operation who gain
information that is relevant to law compliance by other corporate employees will pass
on the information to the employees who can use it to improve corporate law compli-
ance.”). Some courts using the constructive-knowledge rule may have relied unwit-
tingly on the corporate rule, at least to the extent of allowing that mode of
aggregation to color their understanding of “collective knowledge” in the Fourth
Amendment context. See, e.g., United States v. Brown, 322 F. Supp. 2d 101, 105 (D.
Mass. 2004) (“In assessing probable cause, a court will be guided by the “collective
knowledge” or “fellow officer” rule, under which the aggregate knowledge of all
officers involved in the investigation will be imputed to the officer making the
arrest.”).
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2007] constructive knowledge 1095
turns on whether that knowledge was sufficient for probable cause.
32
While the language of the rule varies from one jurisdiction to
another, the courts have settled on a few key terms that reappear, with
only minor variations, in each rendition.
One version, for example, says that “[p]robable cause may be
established from the collective knowledge of the police rather than
solely from the officer who actually made the arrest,”
33
while another
says that “[p]robable cause may emanate from the collective knowl-
edge of the police, though the officer who performs the act of arrest-
ing or searching may be far less informed.”
34
Some courts have gone
further, saying that under the collective-knowledge approach, the
“entire knowledge of the police force is pooled and imputed to the
arresting officer for the purpose of determining if sufficient probable
cause exist[ed] for an arrest.”
35
These formulations say nothing about what must occur before
knowledge may be deemed “collective.”
36
But despite this talk about
32 See, e.g., United States v. Hensley, 469 U.S. 221, 231 (1985) (“[W]hen evidence
is uncovered during a search incident to an arrest in reliance merely on a flyer or
bulletin, its admissibility turns on whether the officers who issued the flyer possessed
probable cause to make the arrest. It does not turn on whether those relying on the
flyer were themselves aware of the specific facts which led their colleagues to seek
their assistance.”).
33 Thacker v. City of Columbus, 328 F.3d 244, 256 (6th Cir. 2003) (quoting Col-
lins v. Nagle, 892 F.2d 489, 496 (6th Cir. 1989)).
34 Milline v. United States, 856 A.2d 616, 620 (D.C. 2004) (quoting United States
v. Hawkins, 595 F.2d 751, 752–53 n.2 (D.C. Cir. 1978)); see also State v. Johnson, 682
So. 2d 385, 391 (Ala. 1996) (quoting the same language from Boyd v. State, 542 So. 2d
1276, 1284 (Ala. 1999)). For other statements of the doctrine, see 2
L
A
F
AVE
, supra
note 8, § 3.5(c), at 289 n.81 (collecting cases). For a sardonic take on the doctrine,
R
see Albo v. State, 477 So. 2d 1071, 1074, 1075 n.4 (Fla. Dist. Ct. App. 1985) (interpret-
ing Hensley to mean that “just as the police may permissibly act upon their collective
knowledge, so they are restrained by their collective ignorance,” and therefore citing
“what we choose to call the ‘collective knowledge-collective ignorance’ rule of Whiteley
and Hensley”); see also Ott v. State, 600 A.2d 111, 114 (Md. 1992) (using the same
term). On Whiteley, see infra note 49.
R
35 State v. Riley, 568 N.W.2d 518, 523 (Minn. 1997) (quoting Stalz v. Conaway,
319 N.W.2d 35, 40 (Minn. 1982)); see also Pyles v. State, 755 S.W.2d 98, 109 (Tex.
Crim. App. 1988) (“[T]he sum of the information known to the cooperating agencies
or officers at the time of an arrest or search by any of the officers involved is to be
considered in determining whether there was sufficient probable cause.”); State v.
Orta, 604 N.W.2d 543, 549 (Wis. 2000) (noting that “the collective knowledge doc-
trine allows officers and their agencies to pool knowledge in determining reasonable
suspicion”).
36 A few courts have stated the rule more narrowly and precisely. See, e.g., Baker
v. State, 556 S.E.2d 892, 905 (Ga. Ct. App. 2001) (Eldridge, J., dissenting) (“The ‘col-
lective knowledge’ rule is applicable to factual situations where the collective knowl-
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1096 notre dame law review [vol. 82:3
collecting all knowledge known to the police, courts have traditionally
applied the rule to a collectivity made for two—the officer who issued
the instruction and the one who acted on it.
37
Their “collective
knowledge” is simply the knowledge of the officer who issued the
order.
Cases displaying the agency approach date back to at least the
1920s, but the doctrine did not start to gain traction until the 1960s.
38
The first use of the term “collective knowledge” in this context
appeared in Williams v. United States,
39
a 1962 D.C. Circuit opinion by
Warren Burger, then a circuit judge, whose summation of the rule is
still frequently quoted.
40
Convicted of robbery and assault, the defen-
edge of law enforcement officers has been relayed to and used by officers actually making
or implementing a detention or seizure.” (emphasis added)); State v. Soldahl, 15 P.3d
564, 567 (Or. 2000) (“The [collective-knowledge] doctrine . . . permits a police officer
to act if the officer reasonably relies on instructions from an officer who has probable
cause.” (emphasis added)); Staats v. Brown, 991 P.2d 615, 633 (Wash. 2000) (Tal-
madge, J., concurring in part, dissenting in part) (“[U]nder the fellow officer rule,
information conveyed by one law enforcement officer to another is sufficient to support prob-
able cause” (emphasis added) (citing Torrey v. City of Tukwik, 882 P.2d 799 (Wash.
Ct. App. 1994))).
37 Of course, where the instruction is issued through a bulletin or broadcast,
there may be numerous officers on the receiving end—but the “collective knowledge”
remains the knowledge of the officer who was the source of the instruction.
38 For example, in Kratzer v. Matthews, 206 N.W. 982 (Mich. 1926), the court
upheld an arrest conducted in response to a telegram stating only that the sender had
a warrant for the arrest of Frank Kratzer and directing the recipient to arrest him. Id.
at 983. The court held that the arresting officer was not required to know the facts
justifying the arrest: “The telegram was received from one whom the defendant knew
to be a police officer at South Bend. He had a right to assume that the warrant was
legally issued.” Id. The dissent, pointing to an 1885 precedent, objected that the
telegram should have “give[n] information sufficient to constitute reasonable cause
to believe a felony had been committed,” id. at 984, and added:
It may be said that times have changed and old procedure is not swift
enough to meet modern needs. It would seem sufficient answer to this to
merely note that constitutional rights remain the same . . . . It is no hardship
to the officer to require him, before making an arrest, to have a reasonable quantum of
knowledge of why he is making the arrest.
Id. at 985 (Wiest, J., dissenting) (emphasis added). This last assertion sets out the
view that the collective-knowledge rule rejects. In fact, since the time of Williams,
courts have found this view so implausible that it is difficult to find any decision stat-
ing that the probable-cause standard could ever have been thought to require that an
officer acting on another’s instructions must know “why he is making the arrest.”
39 308 F.2d 326 (1962).
40 See, e.g., United States v. Colon, 250 F.3d 130, 135 (2d Cir. 2001); United States
v. Terry, No. 2:02-CR-20135, 2002 WL 1803759, at *6 (W.D. Tenn. July 30, 2002);
United States v. Rodriguez, 169 F. Supp. 2d 319, 325 (D. Vt. 2001); Carson v. Lewis, 35
F. Supp. 2d 250, 261 (E.D.N.Y. 1999).
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2007] constructive knowledge 1097
dant in Williams argued that his arrest was invalid because the arrest-
ing officer “did not have adequate first hand information and was
acting on [another officer’s] instructions.”
41
The court rejected this
theory:
[I]n a large metropolitan police establishment the collective knowl-
edge of the organization as a whole can be imputed to an individual
officer when he is requested or authorized by superiors or associates
to make an arrest. The whole complex of swift modern communica-
tion in a large police department would be a futility if the authority
of an individual officer was to be circumscribed by the scope of his
first hand knowledge of facts concerning a crime or alleged
crime.
42
While the “complex of swift modern communication” intensifies
the dilemma, the concerns addressed here are relevant even for face-
to-face communication, and arguably apply even to the “hue and cry”
used in medieval times to pursue criminals.
43
In a fast-moving situa-
41 308 F.2d at 327. The court’s characterization of Williams’s position is poten-
tially misleading. A rule requiring “first hand information” for an arrest would be
unworkable, because no police department could operate effectively if arrests had to
be based on evidence personally observed by the arresting officer. On appeal, Wil-
liams was represented by counsel from Arnold, Fortas & Porter, who presumably
argued that the arresting officer lacked any information about the reasons for sus-
pecting Williams of the crime.
42 Id.
43 The “hue and cry” was the means by which the victim of a crime alerted the
neighborhood and sought help in pursuing the felon. See 2 Canute, c. 29 (1027),
reprinted in
T
HE
L
AWS OF THE
K
INGS OF
E
NGLAND FROM
E
DMUND TO
H
ENRY
I
189 (A.J.
Robertson ed. & trans., 1925) (“[I]f anyone comes upon a thief and of his own
accord lets him escape without raising the hue and cry, he shall make compensa-
tion . . . or clear himself . . . [by stating] that he did not know him to be guilty of any
crime. And if anyone hears the hue and cry and neglects it, he shall pay the fine for
insubordination to the king . . . .”); Statute of Winchester, 13 Edw. I, c. 1, 4 (1285)
(“Cries shall be solemnly made in all Counties, Hundreds, Markets, Fairs, and all
other Places where great Resort of People is, so that none shall excuse himself by
Ignorance”).
To raise the hue and cry, it appears to have been sufficient to describe the sus-
pect and the crime, without having to explain why the suspect was the person being
sought. Records of false arrests in England date back to the fourteenth century, and
in some of these cases, “the exact cause of the arrest is not specified.” Jack K. Weber,
The Birth of Probable Cause, 11
A
NGLO
-A
M
. L. R
EV
.
155, 156 (1982).
Hale states that “[t]he party, that levies [hue and cry], ought to come to the
constable of the vill, and give him notice of a felony committed, and give him such
reasonable assurance thereof as the nature of the case will bear.” 2
S
IR
M
ATTHEW
H
ALE
, T
HE
H
ISTORY OF THE
P
LEAS OF THE
C
ROWN
100 (1736). It is unclear whether the
“reasonable assurance” refers to the details of the felony, the grounds for suspecting
the accused, or both. Hale goes on to list the details that the complainant must pro-
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1098 notre dame law review [vol. 82:3
tion, the police may be pursuing several suspects at the same time. A
requirement that others cannot take up the chase until they receive
detailed information about every suspect, so that the pursuers under-
stand why there is probable cause for each arrest, would be counter-
productive. It would add an unnecessary barrier to the arrest process,
protecting a right that is in no danger of being violated (because the
pursuit is already justified by probable cause), and would simply
ensure that fewer cases could be dealt with at once and that fleeing
suspects would have more time to escape.
After its articulation in Williams, the collective-knowledge rule
was quickly taken up by other courts,
44
and was eventually endorsed by
the Supreme Court in United States v. Hensley,
45
which made it clear
that the rule applies to reasonable suspicion as well as probable cause.
Hensley involved a Terry stop of a driver identified in a “wanted” flyer.
The suspect was indicted on a firearms charge, and he sought to sup-
press the evidence, arguing that the flyer provided no information
that could create reasonable suspicion for the stop.
46
The Court held
vide, but the list does not include the grounds for suspicion. Instead, Hale says that
the complainant must describe the suspect as carefully as possible and that if the
circumstances do not allow a description, the constable must “make hue and cry after
such as may be probably suspected as being persons vagrant in the same night . . . .”
Id. at 100–01. Hale’s treatise on criminal law was published sixty years after he died in
1676, and so his work describes seventeenth-century practice.
Hawkins’s early eighteenth-century treatise is no clearer about a requirement to
spell out the grounds for suspecting the accused. See 2
W
ILLIAM
H
AWKINS
, A T
REATISE
OF THE
P
LEAS OF THE
C
ROWN
75 (Garland Publ’g, Inc. 1978) (1721) (“Hue and Cry is
the Pursuit of an Offender from Town to Town till he be taken . . . . In order to
rightly raise a Hue and Cry, you ought to go to the Constable of the next Town, and
declare the Fact, and describe the Offender, and the Way he is gone . . . . Also every
private Person is bound to assist an Officer demanding his Help for the taking of a
Felon . . . .”); see also
W
ILLIAM
B
LACKSTONE
, 4 C
OMMENTARIES
*
291 (“The party raising
[hue and cry] must acquaint the constable of the vill with all the circumstances which
he knows of the felony, and the person of the felon”); Thomas Y. Davies, Recovering the
Original Fourth Amendment, 98
M
ICH
. L. R
EV
. 547, 623 n.198 (1999) (“The traditional
hue and cry appears to have fallen into disuse in late eighteenth-century America. . . .
To the extent that the hue and cry persisted in framing-era America, it may have been
used primarily to convey information about wanted felons to adjoining counties, thus
avoiding the cumbersome procedure of ‘backing’ warrants (i.e., having an arrest war-
rant issued in another county endorsed by a justice of the peace of the local county
before it could be executed). Thus, the hue and cry may have been transformed into
the nineteenth-century ‘wanted’ poster.”).
44 See, e.g., Lee v. United States, 376 F.2d 98, 100 n.3 (9th Cir. 1967); United
States v. Herberg, 35 C.M.A. 253 (1965); State v. Wilson, 212 A.2d 75, 76 (Conn.
1965); Gilmore v. State, 283 A.2d 371, 378–79 (Md. 1971).
45 469 U.S. 221 (1985).
46 Id. at 223–26.
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that even without that information, the flyer provided a sufficient
basis for the stop:
[W]hen evidence is uncovered during a search incident to an arrest
in reliance merely on a flyer or bulletin, its admissibility turns on
whether the officers who issued the flyer possessed probable cause to
make the arrest. It does not turn on whether those relying on the
flyer were themselves aware of the specific facts which led their col-
leagues to seek their assistance. In an era when criminal suspects
are increasingly mobile and increasingly likely to flee across jurisdic-
tional boundaries, this rule is a matter of common sense: it mini-
mizes the volume of information concerning suspects that must be
transmitted to other jurisdictions and enables police in one jurisdic-
tion to act promptly in reliance on information from another
jurisdiction.
47
Hensley reiterates Williams’s concern with speed and efficiency,
now cast in terms of interjurisdictional communication. Notably,
Hensley did not undertake any balancing analysis to assess the merits
of the collective-knowledge rule—because there are no interests that
require balancing. If an officer has probable cause to suspect some-
one of a crime and alerts others to that fact, his failure to relay the
underlying details does not invade the suspect’s liberty, privacy, or
autonomy interests, nor does it encourage conduct that would jeop-
ardize those interests on the part of other citizens.
48
Further, as Hens-
ley makes clear, the rule operates symmetrically, upholding the arrest
only if there was probable cause for the instruction.
49
47 Id. at 231.
48 To be sure, the collective-knowledge rule increases the number of arrests with-
out probable cause, because if an officer mistakenly believes that she has probable
cause and issues a call to other officers to look out for the suspect, the latter faces a
greater likelihood of being apprehended when more officers are looking for him.
But that observation merely shows that with the collective-knowledge rule in place,
the ratio of invalid arrests remains the same as before: the rule magnifies the capture
rate across the board, presumably applying to permissible and impermissible arrests
in the same measure. That the rule does not diminish the ratio of arrests in the latter
category, by comparison with the ratio of such arrests in a world without the rule,
does not demonstrate that as a general matter, it increases the incidence of invalid
arrests in a way that alters the Fourth Amendment balance between law enforcement
interests and the right of the public to be let alone.
49 The Court had earlier addressed this aspect of the rule—briefly and without
analysis—in Whiteley v. Warden, 401 U.S. 560 (1971). In Whiteley, the police had
obtained an arrest warrant and issued a radio bulletin that led to the suspect’s arrest,
but the Court held that the arrest was invalid because the warrant was not supported
by probable cause. Id. at 564–65. The Court simply stated, without reference to Wil-
liams or any other collective-knowledge decision, that (1) when responding to
another officer’s call for aid, an officer is “entitled to assume that [the request was
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1100 notre dame law review [vol. 82:3
In essence, Williams and Hensley reasoned that once an officer has
devoted time and resources to establishing probable cause, that prod-
uct should be distributed widely, like any other public good that is
relatively costly to produce and relatively cheap to transmit. Moreo-
ver, rapid circulation significantly enhances its value in this case: some
kinds of information about a suspect may be quick to stale (her
clothes, her means of transportation), and the suspect may be up to
no good. The faster the information can be distributed, the more
likely it is to produce results and to prevent further harm.
Hensley illustrates this point even more clearly than Williams,
given that the information was circulated in a flyer (allowing it to
reach a wider audience than an oral instruction normally would) and
was sent to numerous other jurisdictions (not just other officers in the
same department). Ensuring that a bulletin properly articulates a suf-
ficient legal basis for apprehending a suspect is potentially costly in
terms of time and human resources, and if the validity of the arrest
turned on the inclusion of those details, then inevitably some arrests
would be rendered illegal merely because of a clerical error on the
sender’s part.
50
Because the precondition for the rule is that probable
cause must already exist, the savings produced by the rule comes from
reduced costs in apprehending the suspect, rather than any burden
on the general public in the form of diminished privacy. The collec-
tive-knowledge rule thus offers an especially pure example of a rule
that increases the efficacy of policing without tipping the Fourth
Amendment balance.
Rules fitting the same general description, though arguably with
less innocuous effects on that balance, have been filling the Fourth
Amendment hornbooks ever since the exclusionary rule was adopted.
based on] information requisite to support . . . probable cause”; and (2) “an otherwise
illegal arrest cannot be insulated from challenge by the decision of the instigating
officer to rely on fellow officers to make the arrest.” Id. at 568. For further discussion
of Whiteley, see 2
L
A
F
AVE
, supra note 8, § 3.5(b).
R
50 The situation would be different from the problem of typographical errors in
affidavits, which do not normally invalidate warrants. See, e.g., Green v. State, 799
S.W.2d 756, 757–58 (Tex. Crim. App. 1990). But see State v. Endo, 924 P.2d 581,
585 (Haw. Ct. App. 1996). That is because probable cause for a warrant is premised
on what the affiant knows, and while typographical errors may misstate her knowl-
edge, they do not alter it. Indeed, the usual procedure in such cases is to have the
affiant put on testimony to correct the errors and to show that she did have sufficient
information for probable cause. But if the acting officer’s understanding of the basis
for an arrest were a necessary precondition for validating the arrest, and that under-
standing rested on erroneous details, the suspect might plausibly argue that the
arresting officer lacked probable cause.
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2007] constructive knowledge 1101
One line of decisions, following United States v. Leon,
51
blocks the
application of the exclusionary rule unless it would have a “deterrent
effect” in preventing illegal searches.
52
To understand the effect of
this reasoning, consider the result that would follow if all invalid war-
rants, and not just those that are clearly invalid on their face, fell
within the exclusionary rule. A department that sought proactively to
steer clear of the rule, rather than just plunging ahead and taking its
chances, would have the burden of establishing in every instance that
the warrant was beyond reproach. The department would have to do
the same in cases involving reliance on apparently (but not incontro-
vertibly) valid statutes,
53
consent to search granted by apparently (but
not incontrovertibly) competent persons,
54
entry based on reasonable
(but erroneous) belief that the owner of the house had consented,
55
and so on. Perhaps a department that earnestly pursued that course
could significantly improve its accuracy for cases in the gray zone. But
given that most of the relevant violations appear legitimate at first
glance, the gray zone is large.
The cost to the department of such a policy would vastly outweigh
its benefits, because it would require verification for many cases that
appear to raise no concerns and that prove, on inspection, to raise no
concerns. The practical result of the Leon analysis, then, is to create
yet another context for the Fourth Amendment’s requirement of rea-
sonableness: so long as a department’s investigatory procedures
require a level of care and thoroughness that is reasonably calculated
to establish probable cause in the normal case, those procedures are
51 468 U.S. 897 (1984).
52 See, e.g., Arizona v. Evans, 514 U.S. 1 (1995).
53 Illinois v. Krull, 480 U.S. 340 (1987). The Court balanced “the likelihood of
. . . deterrence [of future unlawful police conduct] against the costs of withholding
reliable information from the truth-seeking process.” Id. at 347. That cost may be
understood to refer not only to the harm suffered by the victim, and future potential
victims, because of a failed prosecution in the case at hand, but also more generally to
the additional expenses (in time, money, and human resources) borne by the police
if they are prohibited from using the challenged means of establishing probable cause
during the pre-trial truth-seeking process.
54 United States v. Grap, 403 F.3d 439, 444–45 (2005).
55 Illinois v. Rodriguez, 497 U.S. 177, 186 (1990) (“The Constitution is no more
violated when officers enter without a warrant because they reasonably (though erro-
neously) believe that the person who has consented to their entry is a resident of the
premises, than it is violated when they enter without a warrant because they reasona-
bly (though erroneously) believe they are in pursuit of a violent felon who is about to
escape.”).
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1102 notre dame law review [vol. 82:3
sufficient for probable cause in every case that looks like a normal one
to a “reasonably well trained officer.”
56
Rather than having to raise the cost generally of its information-
gathering protocols to improve its performance at the margin, the
department is permitted, for the price of the usual probable-cause
determination, to keep those determinations that appear to meet the
standard and that would only have been seen to be wanting at an
unreasonable investigatory cost.
57
In short, Leon and its progeny
effectually create a regime in which the process of establishing proba-
ble cause comes at a relatively stable cost, and by adhering to a basic
standard of care, the department ensures that whatever that process
produces is admissible in court.
Another line of cases, following Katz v. United States,
58
holds down
investigatory costs by limiting a search to those places and activities in
which the suspect has a “reasonable expectation of privacy.”
59
In these
cases, the Court has reasoned that if third parties might lawfully
occupy a vantage point where they could see, hear, or smell the
incriminating details that create sufficient cause, then law enforce-
ment officials are not engaged in a search, and therefore need no
legal justification, when they position themselves and use perception-
enhancing devices to collect the same information.
60
56 Leon, 468 U.S. at 922 n.23.
57 One might respond that the department is not being asked to undertake cost-
lier investigations; it is simply being told that when it errs, the product is off limits.
The pragmatic solution to that message would be to forsake the few false positives
rather than curtail other activities for the very marginal benefit of identifying them in
advance and finding an alternative means of establishing probable cause in those
cases. But Leon suggests that when the usual level of care produces generally accept-
able results, and the department cannot reasonably work proactively to improve its
performance, exclusion achieves nothing that § 1983 liability would not similarly
achieve, and thus exclusion would be a windfall just as § 1983 liability would be in
such a case. See William J. Stuntz, Warrants and Fourth Amendment Remedies, 77
V
A
. L.
R
EV
.
881, 910–15 (1991).
58 389 U.S. 347 (1967).
59 Id. at 360 (Harlan, J., concurring).
60 See, e.g., Dow Chem. Co. v. United States, 476 U.S. 227, 229 (1986) (flyover
photographs “from altitudes of 12,000, 3,000, and 1,200 feet” using “precision aerial
mapping camera”); United States v. Place, 462 U.S. 696, 707 (1983) (“canine sniff”);
Coolidge v. New Hampshire, 403 U.S. 443, 465 (1971) (plurality opinion) (plain
view); see also supra notes 22, 28 and accompanying text (discussing the Court’s will-
R
ingness to approve rules that lower investigatory costs without compromising citizens’
rights to be free from invasive searches).
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While the expense of such tactics may not be negligible,
61
they
may still represent significant savings in time and personnel, given
that it might take much longer to establish sufficient cause through
other channels, if that is even possible at all. At a minimum, the
police have a potentially cheaper option to consider when developing
an investigatory plan. This line of cases yields a principle that comple-
ments the lesson of Leon and its progeny: if an ordinary citizen could
legally obtain the information, the police are not required to jump
through additional bureaucratic hoops for the same thing.
62
Numerous other holdings have reinforced these basic principles.
Whren v. United States
63
held that police may legitimately use a minor
traffic violation as a reason to stop a vehicle when they suspect the
driver of an unrelated offense but have no articulable basis for stop-
ping him on that ground.
64
The result is to lower investigatory costs
by allowing the police to use whatever legitimate rationale comes most
readily to hand to start developing probable cause, rather than requir-
ing police to wait until they have a justification related to the offense
they actually seek to investigate.
65
Similarly, Murray v. United States
66
held that if the police have
probable cause for a warrant but conduct a warrantless search that
yields additional incriminating evidence, this “tainted” evidence may
be “sanitized” if they obtain a warrant (on the basis of the information
they already had before the search) and see the same evidence when
they return.
67
This holding reduces costs by allowing the police to
conduct a search first and then to decide whether to obtain a warrant.
That option may not only eliminate bureaucratic hassle, if the search
is fruitless, but may also let the police save for another day the infor-
mation that would have been wastefully disclosed in an affidavit.
61 See, e.g., Dow Chem., 476 U.S. at 242 n.4 (Powell, J., concurring in part and
dissenting in part) (“The camera used ‘cost in excess of $22,000.00.’” (quoting Dow
Chem. Co. v. United States, 536 F. Supp. 1355, 1357 n.2 (E.D. Mich. 1982))).
62 See supra cases cited in note 60.
R
63 517 U.S. 806 (1996).
64 Id. at 813–16.
65 The same thing has long been permitted in the context of prosecutions, with-
out the need for any newly elaborated doctrine to justify it. See Daniel C. Richman &
William J. Stuntz, Al Capone’s Revenge: An Essay on the Political Economy of Pretextual
Prosecution, 105
C
OLUM
. L. R
EV
. 583, 588–99 (2005). Just as these Fourth Amendment
rules offer ways to economize on the cost of developing probable cause, a similar
analysis may lead the prosecutor to economize on the cost of prosecution by targeting
tax evasion instead of racketeering—most saliently because it may be easier to
develop probable cause for the former by comparison with the latter.
66 487 U.S. 533 (1988).
67 Id. at 541.
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1104 notre dame law review [vol. 82:3
These principles also apply to rights under the Fifth and Sixth
Amendments related to the information-gathering process. Miranda
v. Arizona
68
held that during an interrogation of a suspect in custody,
the police are required only at the outset to inform the suspect of her
rights and to ask her if she understands them.
69
The police are then
free to try to induce the suspect to talk by (for example) lying about
the availability of incriminating evidence. The price of uttering the
Miranda formula is sufficient to render admissible any statement the
suspect subsequently makes. Again, the determination of whether a
suspect made a request for counsel is an “objective inquiry,” and so
the police are not required to cease questioning “if . . . a reasonable
officer in light of the circumstances would have understood only that
the suspect might be invoking the right to counsel.”
70
This rule spares
the police the cost of having to accede to a statement that fails to
“meet the requisite level of clarity,”
71
and in effect it evaluates a
request to the police as if it were a statement made to some member
of the public. Where the latter would not hear clarity, the police are
not required to do anything at all to ascertain the suspect’s meaning,
and may proceed with their questions. But the objective analysis that
treats all interlocutors as fungible overlooks the fact that suspects
being interrogated often express themselves more deferentially and
tentatively than they would to a member of the public, and so the
utterance does not have the same meaning in these two hypothetical
speech situations.
72
Like the collective-knowledge rule, these rules reflect an attempt
to remove procedural and logistical barriers to searching and informa-
tion-gathering, so long as the basic balance between the interests of
the police and the public remains undisturbed. But whereas the col-
lective-knowledge rule applies only when probable cause has already
been established, these rules relate to the means of gathering infor-
mation and developing probable cause, and so they raise more diffi-
cult questions about whether they leave that balance undisturbed. In
68 384 U.S. 436 (1966).
69 Id. at 444.
70 Davis v. United States, 512 U.S. 452, 459 (1994).
71 Id.; see also id. at 461 (“[The objective rule] provides a bright line that can be
applied by officers in the real world of investigation and interrogation without unduly
hampering the gathering of information.”).
72 See id. at 469–70 (Souter, J., concurring) (noting that some suspects are “suffi-
ciently intimidated by the interrogation process [and] that the ability to speak asser-
tively . . . abandon[s] them”);
L
AWRENCE
M. S
OLAN
& P
ETER
M. T
IERSMA
, S
PEAKING OF
C
RIME
54–62 (2005) (discussing Davis and the problems it raises in relation to studies
on pragmatics by linguists).
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2007] constructive knowledge 1105
that respect, they raise concerns similar to those presented by the con-
structive-knowledge rule.
B. From Collective Knowledge to Constructive Knowledge
In the 1980s, courts began to apply the conventional collective-
knowledge rule in ways that make it possible to validate an arrest even
when the acting officer lacks probable cause and has received no
instruction. In some instances, another officer has probable cause for
the arrest but has issued no instruction. Relatedly, as we saw in Gillette,
another officer might believe that he has consent to search, and that
belief is then imputed to another officer who received no instruction
to conduct a search.
73
Other cases feature several officers whose “col-
lective knowledge” amounts to probable cause only when aggregated,
because none of them, taken individually, has sufficient information
to justify the arrest.
74
The position that such arrests are lawful has
gained a significant degree of acceptance in state and federal courts,
particularly in the last ten or fifteen years.
While there are important conceptual and normative differences
between collective knowledge and constructive knowledge, the cases
involving these rules are so fact-specific that in some instances they
may be classified under the appropriate rule only after a careful
review. Therefore it is not surprising that courts have sometimes
claimed to be applying the latter rule when actually applying the for-
mer, and vice versa.
The constructive-knowledge rule seems to have received a signifi-
cant boost from a decision displaying that kind of confusion—United
States v. Bernard,
75
decided by the Ninth Circuit in 1980. Bernard
involved an arrest for methamphetamine manufacture after three dif-
ferent DEA agents surveilled the defendant’s mobile home at various
times. The court painstakingly recited the details about what each
agent saw and when,
76
and held that there was probable cause for the
73 See supra notes 2–9 and accompanying text. In fact, the officer who obtained
R
the homeowner’s consent to search his vehicle “testified during the suppression hear-
ing that he believed that the truck belonged to the [homeowner], but he also testified
that his plan was to ascertain the ownership of each vehicle on the premises before
searching that vehicle.” United States v. Gillette, 245 F.3d 1032, 1033 (8th Cir. 2001).
Thus while he might reasonably have believed that he had consent to search the
pickup that turned out to belong to Gillette, according to the officer’s testimony he
would not have conducted the search that his fellow officer conducted unless Gillette
also consented. See id.
74 See infra notes 80–101 and accompanying text.
R
75 623 F.2d 551 (9th Cir. 1980).
76 See id. at 553–54.
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1106 notre dame law review [vol. 82:3
arrest because “‘[t]he officers involved were working in close concert
with each other and the knowledge of one of them was the knowledge
of all.’”
77
This broad holding was unnecessary because two of the
agents shared their observations and “concluded that the suspects
were using the mobile home as a laboratory to produce
methamphetamine.”
78
One of the pair then reported this conclusion
to the third agent, who authorized Bernard’s arrest.
79
Although there
was no express instruction, the case is essentially the same as the other
collective-knowledge cases: the arrest was based on the end-product of
an analysis from an officer who had probable cause, and who did not
relay the underlying details of the analysis.
Nevertheless, because of the way the court talked about imputing
knowledge, Bernard helped to promote the constructive-knowledge
approach. The decision was quickly cited in United States v. Wright,
80
in which the Eighth Circuit held that when a police officer found a
firearm hidden in a closet during a protective sweep, it was “immedi-
ately apparent”
81
to him that the gun was incriminating, because he
was to be credited with an ATF agent’s knowledge that the suspect was
an ex-felon. The court reasoned that the “collective knowledge of the
officers on the scene” should be considered because “ATF special
agents and local police officers were working closely together during
the investigation.”
82
The officer who “observ[ed] . . . the shotgun”
therefore had probable cause to seize it “as evidence of another crime
being committed in the presence of the officers, that is, receipt of a
firearm by a convicted felon.”
83
Though “reluctant to impute the knowledge of one law enforce-
ment officer to another” without communication or an order, the
Wright court justified this move by pointing to “the apparent trend in
77 Id. at 561 (quoting Stassi v. United States, 410 F.2d 946, 952 n.7 (5th Cir.
1969)). Stassi, in turn, cited United States v. Romero, 249 F.2d 371 (2d Cir. 1957).
Romero said that “[w]here the agents were working together and in cooperation were
observing the activities of the various participants and informing each other of the progress
of the conspiracy, the knowledge of each was the knowledge of all.” Id. at 374 (emphasis
added). While Stassi did not include the italicized portion of this sentence, that lan-
guage in fact applied to the circumstances in Stassi—as it also did, to a lesser extent,
to the circumstances in Bernard. But the result of this circuitously derived partial
quotation is that Bernard appeared to treat the teamwork of the police as a self-suffi-
cient rationale for imputation, regardless of the degree of communication involved.
78 Bernard, 623 F.2d at 554.
79 Id.
80 641 F.2d 602 (8th Cir. 1981).
81 Id. at 606.
82 Id.
83 Id. at 607.
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the case law.”
84
For support, the court cited numerous cases applying
the collective-knowledge rule in the conventional fashion;
85
the only
case that even raised any question about broadening the rule was Ber-
nard.
86
Wright, in turn, has helped the Eighth Circuit to develop a
particularly robust constructive-knowledge case law,
87
and has
encouraged other courts to treat the imputation of unshared knowl-
edge as an uncontroversial application of the collective-knowledge
rule. Other courts that have embraced the constructive-knowledge
rule include the First,
88
Second,
89
Fifth,
90
Sixth,
91
Seventh,
92
Ninth,
93
84 Id. at 606 n.4.
85 Id. at 606–07.
86 See id. at 606.
87 Besides Gillette, discussed supra notes 2–9 and accompanying text, see United
R
States v. Twiss, 127 F.3d 771, 774 (8th Cir. 1997) (applying the constructive-knowledge
rule where an officer who arguably lacked probable cause ordered a search that
yielded incriminating evidence; another officer working on the investigation had
probable cause and his knowledge was imputed to the one who ordered the search)
and United States v. O’Connell, 841 F.2d 1408, 1418–19 (8th Cir. 1988) (applying the
constructive-knowledge rule where an officer conducted a Terry stop even though he
was not “personally able to identify [the defendant] or aware of the significance of
[the defendant’s car], because other agents present on the scene had knowledge of
both,” and their knowledge could be imputed to the acting officer).
88 United States v. Cook, 277 F.3d 82, 86 (1st Cir. 2002) (“Officers who jointly
make . . . [investigative] stops rarely will have an opportunity to confer during the
course of the stop. Basing the legitimacy of . . . [a] stop solely on what the officer who
first approaches the suspect knows, rather than on the collective knowledge of all of
the officers who participate directly in carrying out the stop, thus makes little sense
from a practical standpoint. . . . [W]hile . . . a broad rendition of the collective knowl-
edge principle could promote illegal searches, . . . a far more limited application of
the principle, one which takes into account only the knowledge of officers present at
the scene and directly involved in effectuating a stop, is unlikely to encourage illegal
police activity.”).
89 United States v. Colon, 250 F.3d 130, 136 (2d Cir. 2001) (“[A]pplication of the
imputed knowledge doctrine requires that at some point along the line, some law
enforcement official—or perhaps some agglomeration of such officials—involved
must possess sufficient information to permit the conclusion that a search or arrest is
justified.”).
90 United States v. Kye Soo Lee, 962 F.2d 430, 435 (5th Cir. 1992) (“It is not
necessary that the arresting officer himself have personal knowledge of all of the
facts. . . . ‘[P]robable cause can rest upon the collective knowledge of the police,
rather than solely on that of the officer who actually makes the arrest, when there is
“some degree of communication between the two.”’” (quoting United States v.
Ashley, 569 F.2d 975, 983 (5th Cir. 1978))).
91 Collins v. Nagle, 892 F.2d 489, 495 (6th Cir. 1989) (explaining that even where
facts relevant to the determination of probable cause were not shared, knowledge of
investigators working together on the scene is “mutually imputed”).
92 United States v. Sawyer, 224 F.3d 675, 680 (7th Cir. 2000) (“When law enforce-
ment officers are in communication regarding a suspect, the knowledge of one officer
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1108 notre dame law review [vol. 82:3
and Eleventh
94
Circuits, district courts in the Fourth and Tenth Cir-
cuits,
95
and several state courts.
96
Courts adopting the rule generally limit its application by attach-
ing the proviso that officers must be “working closely together,”
97
can be imputed to the other officers under the collective knowledge doctrine.”); see
also United States v. Nafzger, 974 F.2d 906, 911 (7th Cir. 1992) (“[W]hen officers are
in communication with each other while working together at a scene, their knowl-
edge may be mutually imputed even when there is no express testimony that the spe-
cific or detailed information creating the justification for a stop was conveyed . . . .”);
United States v. Edwards, 885 F.2d 377, 383 (7th Cir. 1989) (imputing knowledge of
one arresting officer to another because officers “made the arrest together”).
93 Burrell v. McIlroy, 423 F.3d 1121, 1124 & n.2 (9th Cir. 2005) (officer who was
asked only to watch suspect’s apartment, and who observed no suspicious conduct,
had probable cause to arrest; “[b]ecause the detectives were working in close concert,
a court may consider the collective knowledge of these detectives in considering their
beliefs concerning probable cause or reasonable suspicion”).
94 United States v. Kapperman, 764 F.2d 786, 791 n.5 (11th Cir. 1985) (looking
to collective knowledge of officers where there was “minimal” communication
between officers).
95 United States v. Flowers, No. 02-40108-01-SAC, 2003 WL 356057, at *6 (D. Kan.
Jan. 13, 2003) (“[T]he court will aggregate . . . [the investigating officers’] knowledge
as this is a situation where two officers are working closely together . . . .” (quoting
United States v. Shareef, 100 F.3d 1491, 1504 n.6 (10th Cir. 1996))); United States v.
Hagerman, No. 1:02 CV 00106, 2003 WL 21135702, at *5 (W.D. Va. May 13, 2003).
96 See, e.g., Smith v. State, 719 So. 2d 1018, 1022 (Fla. Dist. Ct. App. 1998); State v.
Conley, 616 S.E.2d 174, 175 n.1 (Ga. Ct. App. 2005) (“Under . . . [the collective
knowledge] doctrine, probable cause ‘can rest upon the collective knowledge of the
police when there is some degree of communication between them, instead of the
arresting officer alone.’” (quoting Burgeson v. State, 475 S.E.2d 580, 583–84 (Ga.
1996))); State v. Landry, 729 So. 2d 1019, 1022 (La. 1999) (instructing trial court on
remand that “the court may consider all of the information known collectively to the
law enforcement personnel involved in the investigation” and that “‘[p]robable cause
can . . . be demonstrated through the collective knowledge of police officers involved
in an investigation, even if some of the information known to other officers is not
communicated to the arresting officer’” (quoting United States v. Butler, 74 F.3d 916,
921 (9th Cir. 1996))); People v. Davis, 660 N.W.2d 67, 70–71 (Mich. 2003) (“[N]o
evidence existed that . . . [two officers] communicated to each other the information
that they acquired from interviewing witnesses at the scene. Such a communication
was not required. Under the collective-knowledge theory, the trial court properly
considered the information that both officers possessed and found that the informa-
tion, in its totality, constituted probable cause for defendant’s arrest.”); State v.
Harper, No. 95-0380-CR, 1995 WL 490694, at *2 (Wis. Ct. App. July 5, 1995).
97 See, e.g., Flowers, 2003 WL 356057, at *6 (“[T]he court will aggregate [the inves-
tigating officers’] knowledge as this is a situation where two officers are working
closely together . . . .” (citing Shareef, 100 F.3d at 1504 n.6)); Hagerman, 2003 WL
21135702, at *5 (“Under the doctrine of collective knowledge, a defendant’s consent
to search is deemed known to other officers working closely together at the scene of
an investigation, regardless of whether that fact is specifically communicated to all
officers.” (citing United States v. Gillette, 245 F.3d 1032, 1034 (8th Cir. 2001))).
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“cooperating in an investigation,”
98
or working in “close time-space
proximity.”
99
The courts disagree about whether unshared knowl-
edge may be imputed if there was no communication among the
officers. Some courts have specified that there must be proof of “at
least minimal communication” but no proof about what was actually
said,
100
while others have said that no communication is required.
101
There has been some disagreement about what is required to show that officers were
working closely together. See, e.g., Gillette, 245 F.3d at 1034 (concluding that officers
were “work[ing] together on an investigation” when one officer was “searching the
house” and another arrived in response to a call for backup and immediately “began
to search [the] vehicles” in the driveway); id. at 1035–36 (Alsop, J., dissenting) (argu-
ing that officers could not have been “working closely together” under those
circumstances).
98 See, e.g., Savino v. City of New York, 331 F.3d 63, 69 (2d Cir. 2003) (invoking
collective-knowledge rule and stating that “‘where law enforcement authorities are
cooperating in an investigation . . . the knowledge of one is presumed shared by all’”
(quoting Illinois v. Andreas, 463 U.S. 765, 772 n.5 (1983))); United States v. Igbara,
No. 95-0380-CR, 2002 WL 31779812, at *2 (N.D. Ill. Dec. 9, 2002).
99 See, e.g., In re M.E.B., 638 A.2d 1123, 1136 n.3 (D.C. 1993). The “time-space
proximity” rationale appears to come from the first edition of LaFave’s treatise cited
supra note 8; Smith, 719 So. 2d at 1022–23; Harper, 1995 WL 490694, at *2 (unpub-
R
lished decision); see 2
L
A
F
AVE
,
supra note 8, § 3.5(c). LaFave, however, simply noted
R
that a search is not “inevitably” impermissible when one officer makes an arrest that
can be justified by the facts known to another officer who is “at hand.” Id. § 3.5(c), at
288. LaFave did not state, as Smith, Harper, and M.E.B. do, that the knowledge of such
a cooperating officer may always be imputed to the acting officer.
100 See, e.g., United States v. Waldrop, 404 F.3d 365, 370 (5th Cir. 2005) (“some
general communication” (citations omitted)); United States v. Terry, 400 F.3d 575,
581 (8th Cir. 2005) (“‘some degree of communication’” (citations omitted)); United
States v. Nafzger, 974 F.2d 906, 914 (7th Cir. 1992) (officers “were part of a coordi-
nated investigation, and all were in close communication with the same command
post”); United States v. Kye Soo Lee, 962 F.2d 430, 435 (5th Cir. 1992) (“‘some
degree of communication’” (citation omitted)); United States v. Wilson, 894 F.2d
1245, 1254 (11th Cir. 1990) (“at least minimal communication”); Collins v. Nagle, 892
F.2d 489, 495 (6th Cir. 1989) (same); Johnson v. State, 660 So. 2d 648, 654 (Fla. 1995)
(“Under the fellow-officer rule, information shared by officers investigating a crime is
imputed to any one of their number, even those from different agencies working
together.”).
101 See, e.g., United States v. Terry-Crespo, 356 F.3d 1170, 1177 (9th Cir. 2004)
(“[T]here is room in our precedent to conclude that the collective knowledge of law
enforcement can support reasonable suspicion, even if the information known to
others is not communicated to the detaining officer prior to a Terry stop.”); Gillette,
245 F.3d at 1035–36 (Alsop, J., dissenting) (“A small number of cases have relaxed the
communication requirement when the officers involved were “working closely
together” during the execution of a search warrant.”); United States v. Lata, No.
CRIM. 03-224-01-JD, 2004 WL 783080, at *5 n.3 (D.N.H. Apr. 8, 2004) (“[K]nowledge
is imputed . . . under the ‘fellow officer rule’ whether it was communicated to [the
acting officer] or not.” (citing United States v. Meade, 110 F.3d 190, 193–94 (1st Cir.
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The reasoning behind the “minimal communication” rule
appears to be that if a search or arrest occurs when officers are work-
ing together and exchanging information, it may be assumed that
they shared any knowledge necessary to justify the action. For exam-
ple, in United States v. Nafzger,
102
the Seventh Circuit explained that
when officers, stationed in separate places, “were part of a coordi-
nated investigation, and . . . were in close communication with the
same command post,” a Terry stop by one officer could be justified on
the ground that another officer’s suspicions were “presumably relayed
[to] the command post,” and then to the officer who conducted the
stop.
103
The rule thus depends on the inference that if there was any
communication at all, the relevant information was communicated.
The inference may be rebuttable, but it is not clear how a defendant
could rebut it. Further, if the police can prove that they were commu-
nicating, it is not clear why they should not also be required, at the
same time, to put on evidence about what they communicated.
104
The “no communication” rule appears to reflect a different pre-
mise—namely, that officers working together are acting as a “single
organism.”
105
Rather than presupposing a steady stream of communi-
cation among all participants, this characterization treats each individ-
ual as a component of a larger entity. On that view, it is appropriate
to impute unshared information because the team shares a single goal
and the members are working jointly to achieve it. Any action should
be ascribed to the team as a whole and should be analyzed from that
perspective. Bernard’s statement that “‘the knowledge of one of them
1997))); Smith, 719 So. 2d at 1023 (“[T]here was no request or directive to pat down
[the suspect]” but “when [another] officer . . . possess[es] . . . probable cause [and] is
in a close time-space proximity, evidence of a direct communications link between the
officers is not . . . required.”).
102 974 F.2d at 914.
103 Id.; see also United States v. O’Connell, 841 F.2d 1408, 1419 (8th Cir. 1988)
(“[W]e presume the officers have shared relevant knowledge which informs the deci-
sion to seize evidence or to detain a particular person, even if the acting officer is
unable to completely and correctly articulate the grounds for his suspicion at the time
of the search.”).
104 Of course, such a requirement might simply tempt the other officers to lie
about what they said. A general concern about the constructive-knowledge rule is
that it creates incentives for the police to perjure themselves. See infra note 133.
R
105 See, e.g., United States v. Shareef, 100 F.3d 1491, 1504 n.6 (10th Cir. 1996);
United States v. Flowers, No. 02-40108-01-SAC, 2003 WL 356057, at *6 (D. Kan. Jan.
13, 2003).
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was the knowledge of all’”
106
aptly describes the essential premise of
this analysis.
The introduction of the proviso that the officers must be working
closely together might seem to signal the courts’ awareness that the
new rule goes beyond the traditional collective-knowledge rule, and
requires additional justification. Courts have failed to offer any new
rationale, however, and even in decisions with split panels, the major-
ity simply avoids responding to the dissenter who demands a ratio-
nale.
107
Instead, the courts proceed as if they are simply following a
well-established rule.
However, the efficiency justifications for the collective-knowledge
rule have little to offer in support of the constructive-knowledge rule.
The benefits flowing from the new rule occur by chance and cannot
be integrated into a departmental protocol for conducting searches
and arrests. The rule does not enhance the portability of probable
cause generally, so that police departments may improve their search
and communications procedures; instead, the rule simply treats a par-
ticular officer, ex post, as having had probable cause when it would
otherwise have been lacking. The rule does not help police depart-
ments to plan their deployment of personnel, because the rule’s very
premise is that the acting officer did not know what the others knew,
and therefore could not have known in advance whether his action
would prove to have been permissible.
Hensley, Leon, Katz, and Whren all suggest ways that the depart-
ment can conserve costs when developing procedures to establish
probable cause,
108
but the constructive-knowledge rule offers no such
106 United States v. Bernard, 623 F.2d 551, 561 (9th Cir. 1980) (quoting Stassi v.
United States, 410 F.2d 946, 952 n.7 (5th Cir. 1969)); see also State v. Soldahl, 15 P.3d
564, 568 (Or. 2000) (characterizing law-enforcement team as a “unit”); supra note 77
R
and accompanying text (discussing the imputation of knowledge in both Stassi and
Bernard).
107 See, e.g., United States v. Gillette, 245 F.3d 1032, 1035 (8th Cir. 2001) (Alsop, J.,
dissenting) (“Collective action involves the exchange of information and instructions,
and in most instances the collective knowledge theory simply allows one officer to
accept facts or directives communicated by another officer at face value and to take
appropriate action based on that communication.”); Woodward v. State, 668 S.W.2d
337, 355 (Tex. Crim. App. 1982) (Teague, J., dissenting) (“[W]e might as well rip out
of our law the provisions of the Fourth Amendment to the Federal Constitution and
Art. I, Section 9, of the Texas Constitution, as well as cease using in our legal vocabu-
lary the phrase ‘probable cause.’”); White v. Commonwealth, 481 S.E.2d 486, 491 (Va.
Cir. Ct. 1997) (Elder, J., dissenting) (“Fourth Amendment cases dealing with the ‘col-
lective knowledge’ of police officers require that police officers actually communicate
with each other before knowledge will be imputed from one to another.”). In each
instance, the majority chose not to engage these objections.
108 See supra notes 51–64 and accompanying text.
R
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1112 notre dame law review [vol. 82:3
advantages. To be sure, when the rule applies, it spares the officers
the effort of sharing their observations, and it gives them the benefit
of the doubt by assuming that if they had conferred, they would have
analyzed the facts correctly. But the rule cannot generate a means of
generally lowering those costs, which in any case are usually trivial
compared to most other investigatory costs, such as interviewing wit-
nesses, gathering and analyzing evidence, and getting a warrant.
Moreover, the constructive-knowledge rule subtly but significantly
changes the meaning of “probable cause.” The question of whether
the “‘facts, viewed from the standpoint of an objectively reasonable
police officer, amount to’ probable cause”
109
has long been taken to
mean that the court should look to a reasonable officer, standing in
the place of the one who took the disputed action and knowing the
same facts.
110
Courts have only occasionally felt obliged to explain
that probable cause must be focalized
111
through the perspective of
the acting officer,
112
but the principle may be gleaned from nearly
every formulation of the probable-cause standard.
109 Maryland v. Pringle, 540 U.S. 366, 371 (2003) (quoting Ornelas v. United
States, 517 U.S. 690, 696 (1996)). For earlier formulations, see, for example, Carroll v.
United States, 267 U.S. 132, 161 (1925) (“‘If the facts and circumstances before the
officer are such as to warrant a man of prudence and caution in believing that the
offense has been committed, it is sufficient [for probable cause].’” (quoting Stacey v.
Emery, 97 U.S. 642, 645 (1878))) and Wheeler v. Nesbitt, 65 U.S. (24 How.) 544, 545
(1860) (“Probable cause is the existence of such facts and circumstances as would
excite the belief in a reasonable mind, acting on the facts within the knowledge of the
prosecutor, that the person charged was guilty of the crime for which he was
prosecuted.”).
110 Whren v. United States, 517 U.S. 806, 815 (1996) (“While police manuals and
standard procedures may sometimes provide objective assistance, ordinarily one
would be reduced to speculating about the hypothetical reaction of a hypothetical
constable–an exercise that might be called virtual subjectivity.”).
111 Focalization is a term used in narratology to refer to the presentation of a
scene through the subjective perception of a character. See
G
ERALD
P
RINCE
, A D
IC-
TIONARY OF
N
ARRATOLOGY
31–32 (rev. ed. 2003).
112 For opinions stating explicitly that probable cause must be analyzed from the
perspective of the actor who made the arrest, see, for example, Michigan v. DeFil-
lippo, 443 U.S. 31, 37 (1979) (“This Court repeatedly has explained that ‘probable
cause’ to justify an arrest means facts and circumstances within the officer’s knowledge
that are sufficient to warrant a prudent person, or one of reasonable caution, in
believing, in the circumstances shown, that the suspect has committed, is committing,
or is about to commit an offense.” (emphasis added)); Carroll, 267 U.S. at 161–62
(“‘[G]ood faith is not enough to constitute probable cause. That faith must be
grounded on facts within knowledge of the Director General’s agent, which in the
judgment of the court would make his faith reasonable.’” (quoting Director General
v. Kastenbaum, 263 U.S. 25, 28 (1923))); United States v. Parra, 402 F.3d 752, 763–64
(7th Cir. 2005) (“[C]ourts evaluate probable cause ‘not on the facts as an omniscient
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2007] constructive knowledge 1113
The Supreme Court has recently repeated that “‘[t]he substance
of all the definitions of probable cause is a reasonable ground for
belief of guilt.’”
113
A “belief” is a mental act or condition, and hence
it requires a mind capable of entertaining the thought.
114
While there
may be a place for thoughts without a thinker in the Buddhist ecology
of mind,
115
Fourth Amendment law has not traditionally depended on
the view that an opinion or belief can exist without a specifiable agent
whose reasonableness may be assessed.
116
Thus it would seem that if
the facts creating probable cause were not apparent to any particular
observer, no reasonable officer can be posited who could reach a con-
clusion based on those facts, and so probable cause is lacking.
Finally, it is not even clear what limit is entailed by the require-
ment that officers must be “working closely together” or “cooperat-
ing.” As with the collective-knowledge rule before its transmutation,
these provisos have generally been applied more narrowly than their
observer would perceive them but on the facts as they would have appeared to a rea-
sonable person in the position of the arresting officer—seeing what he saw, hearing what
he heard.’” (quoting Mahoney v. Kesery, 976 F.2d 1054, 1057 (7th Cir. 1992)));
United States v. Rivera, 370 F.3d 730, 733 (8th Cir. 2004) (“We evaluate probable
cause not from the perspective of an omniscient observer, but on the facts as they
would have appeared to a reasonable person in the position of the arresting officer.”);
Earles v. Perkins, 788 N.E.2d 1260, 1265 (Ind. Ct. App. 2003) (citing the same lan-
guage from Marshall v. Teske, 284 F.3d 765, 770 (7th Cir. 2002)).
113 Pringle, 540 U.S. at 371 (quoting Brinegar v. United States, 338 U.S. 160, 175
(1949), in turn quoting Carroll, 267 U.S. at 161, in turn quoting McCarthy v. De
Armit, 99 Pa. 63 (Pa. 1881)).
114 See, e.g.,
B
LACK
’
S
L
AW
D
ICTIONARY
164
(8th ed. 2004) (defining “belief” as “[a]
state of mind that regards the existence of something as likely or relatively certain”);
A C
OMPANION TO THE
P
HILOSOPHY OF
M
IND
15 (Samuel Guttenplan ed., 2001) (“[F]or
particular items of consciousness or attitudes, it is simply impossible to have an action
without an agent. . . . [W]e cannot conceive of . . . a subjectless belief.”);
D
ICTIONARY
OF
C
OGNITIVE
S
CIENCES
37 (Olivier Houd´
e ed., 2004) (“In everyday usage, a belief is a
certain psychological state that leads the subject to assent to a given representation
whose epistemic status is unsure or doubtful.”).
115 See, e.g.,
M
ARK
E
PSTEIN
, T
HOUGHTS
W
ITHOUT A
T
HINKER
(
1995); W.S. Waldron,
Buddhist Steps to an Ecology of Mind: Thinking about ‘Thoughts Without a Thinker,’ 34
E
ASTERN
B
UDDHIST
1 (2002); cf.
K
ARL
P
OPPER
, O
BJECTIVE
K
NOWLEDGE
108–09 (1979)
(“Knowledge in the objective sense is knowledge without a knower: it is knowledge with-
out a knowing subject.”).
116 See, e.g., United States v. Gillette, 245 F.3d 1032, 1035 (8th Cir. 2001) (Alsop, J.,
dissenting) (“Although . . . [we] often refer to the ‘collective knowledge’ of the
officers, the term ‘collective knowledge’ is misleading because as a practical matter
individual officers cannot know anything collectively. Individual officers, on the
other hand, can act collectively, and the real issue in our collective knowledge cases is
whether a particular search or seizure is reasonable within the meaning of the Fourth
Amendment in light of any collective action in which two or more officers were
engaging.”).
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1114 notre dame law review [vol. 82:3
potentially broad language might seem to permit. In most cases, the
officers are within each other’s line of vision, or in communication, or
both. But again, as with the collective-knowledge rule, some courts
have attended to the language rather than the traditional application.
We saw at the outset that in Gillette, the court validated a search by an
officer who had no basis for believing it was permissible and who was
not in proximity to his colleagues.
117
The court even went so far as to
say that the officers were “work[ing] together”
118
(in this case drop-
ping the word “closely” from the requirement). Another court
upheld several officers’ seizure of a suspect on the ground that
another officer, who though absent was “working in a joint assign-
ment” with them, turned up shortly afterwards to supply his evi-
dence.
119
These examples show what the future of the constructive-
knowledge rule will look like if the current restrictions evaporate.
Once the requirement is simply that the officers must be working
towards a shared goal, the opportunities for imputation expand dra-
matically. Information gathered remotely could be deemed available
to other officers, making the team something like Star Trek’s Borg Col-
lective, whose group consciousness allows all members, no matter how
widely separated, to share their perceptions and thus to adapt almost
instantaneously to new conditions.
Gillette is also instructive because it shows how the constructive-
knowledge rule interacts with other Fourth Amendment rules. The
court attributed to one officer the knowledge that would have sup-
ported a “reasonable mistake” by one of the others.
120
If constructive
knowledge may be used to impute the basis for a reasonable mistake
about a place to be searched, the same doctrine might justify other
reasonable mistakes—about a suspect’s identity, or a person’s author-
ity, competency, or willingness to consent to a search, for example.
The relevant question would be whether the team, in the aggregate,
had observed details that would justify the acting officer’s mistake.
What is true for probable cause is usually also true for reasonable sus-
picion, and so constructive knowledge might justify a Terry stop as
readily as a full-scale search. Thus under Whren, even if only one
117 See id. at 1033–34 (majority opinion).
118 Id. at 1034.
119 People v. Starr, 634 N.Y.S.2d 132, 134 (N.Y. App. Div. 1995). In this case, one
officer observed suspicious conduct, others seized the suspect without any knowledge
of what their colleague had seen, and “minutes later” the first officer arrived and
described his own suspicions. Id. at 133. Arguably, the officers who seized the suspect
had their own grounds for acting. But the court did not take that view, and instead
justified the seizure on the basis of the first officer’s knowledge. Id. at 133–34.
120 Gillette, 245 F.3d at 1034.
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2007] constructive knowledge 1115
officer in the team knew of a valid pretext for a Terry stop, his knowl-
edge could support a stop by any of the others. Of course, courts
might reject these applications, though it is not clear on what ground.
The constructive-knowledge rule is most likely to be invoked when the
acting officer knew something, but not quite enough; otherwise the
officer might not have acted in the first place. In light of these poten-
tial applications, the rule might achieve in the warrantless context
what Leon does for search warrants—namely, the broadening of the
scope of “reasonableness.” Where an officer’s belief (about probable
cause or the basis for an exception to probable cause) is almost rea-
sonable, he could be imputed with knowledge that would make it
reasonable.
II. C
ONSTRUCTIVE
K
NOWLEDGE AND
I
NEVITABLE
D
ISCOVERY
A pragmatic—but ultimately incomplete—solution to the prob-
lem of constructive knowledge may be found in the “inevitable discov-
ery” rule, which like the collective-knowledge rule, was percolating in
the state and federal courts for some twenty years before it was
endorsed by the Supreme Court in the mid-1980s.
121
Just as prosecu-
tors may avoid the suppression of illegally acquired evidence by show-
ing that the evidence would likely have been discovered through legal
means, it might be argued that when officers are working together on
an investigation, and are searching for evidence of criminal conduct,
they will inevitably share all of the incriminating evidence before they
leave the scene of the crime. On that view, it is a triviality that an
officer made an arrest before finding out what the others learned—in
any case he would have found out at a time when he could still have
arrested the suspect.
So far, no court has defended the constructive-knowledge rule by
analogy to inevitable discovery. However, the requirement that
officers must be in close contact, or must be cooperating in an investi-
gation, arguably could ensure that the rule applies only when the
police would have conferred before leaving the scene.
122
This
121 Nix v. Williams, 467 U.S. 431, 448–50 (1984). On courts’ treatment of the rule
over the previous twenty years, see id. at 440 n.2.
122 The First Circuit appears to have followed this logic when it adopted a version
of the constructive-knowledge rule. The court initially rejected what it regarded as an
overbroad form of the rule, noting that “the collective-knowledge corollary of the
fellow officer rule would seem to require, or at least presuppose, the flow of informa-
tion from the officers with knowledge of facts tending to establish probable cause to
those lacking that knowledge (or, at least, to the directing or arresting officer).”
United States v. Meade, 110 F.3d 190, 194 (1st Cir. 1997). Five years later, the court
endorsed a more constrained version of the rule, stating that “a broad rendition of
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1116 notre dame law review [vol. 82:3
approach, however, does not fully resolve the constructive-knowledge
problem. First, some cases are poor candidates for this analysis,
because the relevant information was not shared after the event, nor
was it likely to be. Second, the imputation of unshared information in
this context raises especially acute problems of hindsight bias and con-
firmation bias. Even in the cases that might appear to be good candi-
dates, the facts may receive poor analysis under this approach.
As to the “inevitable communication” premise, if courts do not
require that the officers must be close to each other or must be in
communication when the action occurs, the “inevitability” of informa-
tion-sharing diminishes appreciably. Moreover, even a physical pres-
ence requirement is not a good proxy for information-sharing,
because the rule imputes all information, regardless of whether it
likely would have been shared. That may help to explain why courts
that decline to adopt the rule do not then turn to “inevitable discov-
ery” for help. Quite the reverse: in some cases, the government
unsuccessfully argues for constructive knowledge and then moves on
to “inevitable discovery,” only to have that argument rejected as
well.
123
There are two reasons for questioning the inevitability of a proba-
ble-cause determination in these cases. First, as noted earlier, the con-
structive-knowledge rule imputes both the unshared information and
the analysis that translates that information into a belief about the
suspect’s criminal conduct.
124
Courts have acknowledged that having
sufficient information for probable cause does not necessarily trans-
late into a proper determination on the issue. So far, however, this
recognition has been limited to the problem of the 911 operator who
has not been trained in the analysis of probable cause and therefore is
not qualified to issue an instruction that could impute the underlying
information.
125
The insight might be extended: the fact that an officer
the collective knowledge principle could promote illegal searches, . . . [but] a far
more limited application of the principle, one which takes into account only the knowl-
edge of officers present at the scene and directly involved in effectuating a stop, is unlikely to
encourage illegal police activity.” United States v. Cook, 277 F.3d 82, 86 (1st Cir.
2002) (emphasis added).
123 See, e.g., State v. Friday, 412 N.W.2d 540, 545–46 (Wis. Ct. App. 1987), rev’d, 434
N.W.2d 85 (Wis. 1989); Damato v. State, 64 P.3d 700, 707 (Wyo. 2003).
124 See supra notes 29–30 and accompanying text.
R
125 See, e.g., United States v. Colon, 250 F.3d 130, 137 (2d Cir. 2001) (refusing to
impute information from a 911 operator who lacked “training and ability to make the
determination that there was probable cause”); see also United States v. Jegede, 294
F. Supp. 2d 704, 707 (D. Md. 2003) (stating that “any information other than that
which was actually disseminated to the . . . officers [by the dispatcher] must be disre-
garded”). But see State v. Carr, 844 P.2d 1377, 1380 (Idaho Ct. App. 1992) (“[T]he
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2007] constructive knowledge 1117
has been trained to assess probable cause does not necessarily mean
that she will always make the appropriate assessment.
Second, some of the constructive-knowledge cases do not involve
joint information-gathering expeditions, while in others the court
amasses all of the details and then uses all of the available expertise to
evaluate them, even though certain facts would likely have been mean-
ingless to the officer who actually discovered them. Because an
officer’s training and experience determines which “points of sali-
ence”
126
will register as indicators of criminal activity, officers sharing
similar backgrounds are likely to notice and analyze similar details,
but an ATF agent, for example, is relatively unlikely (at least without
any advance directive) to pick out the details that would be salient to
one who specializes in financial crime.
Inevitability is a questionable proposition in any case, and there is
significant disagreement about how to apply the “inevitable discovery”
rule itself. As Professor LaFave has stressed, “courts are not always as
cautious . . . as they should be” to prevent a discovery from being
labeled “inevitable” simply on the basis of a “hunch or speculation as
to what otherwise might have occurred.”
127
Some circuits specify that
the rule applies only when the police have already begun a lawful
search that would have led to the discovery of the challenged evi-
dence, while others instead require a showing by clear and convincing
evidence that a lawful search would have been undertaken, and yet
others require only proof by a preponderance of the evidence.
128
collective knowledge of police officers involved in the investigation—including dis-
patch personnel—may support a finding of probable cause.”). Notably, in refusing to
impute the 911 operator’s knowledge, Colon articulated a principle that might be
thought to question the validity of the constructive-knowledge rule more generally:
“In the absence of any showing that any NYPD employee with the training, responsi-
bility or authority to make a determination of reasonable suspicion ever had sufficient
information on which to effect or instigate the stop and search of Colon, this Court
cannot find that the Terry stop was reasonable.” Colon, 250 F.3d at 137 (emphasis
added).
126 Judith Mehta et al., The Nature of Salience: An Experimental Investigation of Pure
Coordination Games, 84
A
M
. E
CON
. R
EV
. 658, 661 (1994).
127 6
L
A
F
AVE
,
supra note 8, § 11.4(a), at 275–76. LaFave adds, “‘It is not enough to
show that the evidence “might” or “could” have been otherwise obtained. . . . [The]
evidence is inadmissible unless the prosecution . . . show[s] that it would have
acquired the evidence in any event.’” Id. at 276 (quoting Robert F. Maguire, How to
Unpoison the Fruit—The Fourth Amendment and the Exclusionary Rule, 55
J. C
RIM
. L., C
RIM-
INOLOGY
, & P
OLICE
S
CIENCE
307, 315 (1964)).
128 See Eugene L. Shapiro, Active Pursuit, Inevitable Discovery, and the Federal Circuits:
The Search for Manageable Limitations Upon an Expansive Doctrine, 39
G
ONZ
. L. R
EV
.
295,
329 (2004); Stephen E. Hessler, Note, Establishing Inevitability Without Active Pursuit:
Defining the Inevitable Discovery Exception to the Fourth Amendment Exclusionary Rule, 99
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1118 notre dame law review [vol. 82:3
Moreover, it is doubtful that a finding of “inevitable communica-
tion” in a given jurisdiction should simply rely on the applicable stan-
dard for “inevitable discovery.” In theory, a suspect could receive
compensation under § 1983 for an illegal search, even if the fruits are
admissible as the product of “inevitable discovery,” because that doc-
trine neutralizes the exclusionary rule but does not validate the
search.
129
The constructive-knowledge rule, on the other hand, helps
to establish probable cause and therefore bars any claim that the sus-
pect’s civil rights were violated. Given this result, it may be appropri-
ate to require a higher standard for “inevitable communication” than
for “inevitable discovery.”
That difference also helps to identify a concern with the “inevita-
ble discovery” rule, a concern that raises even graver questions about
the constructive-knowledge rule. The Fourth Amendment is essen-
tially concerned with foreseeability.
130
If the police have strong
enough reasons for expecting to find evidence relating to an offense,
they are entitled to a search warrant. If their reasons are weaker, but
not negligible, the police can conduct a Terry stop.
How far the police can search is a function of how well they can
predict the outcome. Under a foreseeability rationale, “inevitable dis-
covery” is a plausible barrier to exclusion when the police act with
foreknowledge of the inevitable result. If they know they will lawfully
obtain the evidence later, they can act now, unlawfully, to seize it, at
the cost of possible sanctions under § 1983.
131
That explanation
M
ICH
. L. R
EV
.
238, 243–47 (2000). For a broader critique of the “inevitable discovery”
rule, see Peter Brooks, “Inevitable Discovery”—Law, Narrative, Retrospectivity, 15
Y
ALE
J.L.
& H
UMAN
.
71 (2003).
129 See, e.g., Heck v. Humphrey 512 U.S. 477, 487 n.7 (1994) (“Because of doc-
trines like . . . inevitable discovery,” a party may be convicted on the basis of illegally
obtained evidence and may nevertheless sue for damages; to prevail, “the § 1983
plaintiff must prove not only that the search was unlawful, but that it caused him
actual, compensable injury. . . .”); Chatman v. Slagle, 107 F.3d 380, 382 (6th Cir.
1997) (“[T]he inevitable discovery doctrine is no bar to a § 1983 suit when there has
been no prior state trial.”).
130 See, e.g., United States v. Grubbs, 126 S. Ct. 1494, 1499 (2006) (“Because the
probable-cause requirement looks to whether evidence will be found when the search is
conducted, all warrants are, in a sense, ‘anticipatory.’”).
131 LaFave notes that
the “inevitable discovery” rule should be applied only when it is clear that
“the police officers have not acted in bad faith to accelerate the discovery” of
the evidence in question. But in Nix v. Williams, the Supreme Court rejected
the court of appeals’ limitation that the prosecution must prove the absence
of bad faith, explaining that it “would place courts in the position of with-
holding from juries relevant and undoubted truth that would have been
available to police absent any unlawful police activity” and “would put the
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2007] constructive knowledge 1119
shows how the “inevitable discovery” rule fits in with the other short-
cuts in evidence-gathering discussed earlier.
132
On this view, “inevita-
ble discovery” is not a windfall to the prosecution; instead it is an
instrument that the police may use anticipatorily, and may integrate
into their general search protocols. The rule would then serve, like
Whren, as an actively exploitable tool in the investigatory kit, and not
just as a convenient excuse that may be conjured up after the fact
when it can be made to sound plausible.
That reasoning, however, does not apply to the constructive-
knowledge rule. It is one thing to say that an officer can confidently
anticipate that his colleagues will soon conduct a lawful search, and
quite another to say that an officer knows his colleagues have as-yet-
unshared information that in the aggregate is sufficient for probable
cause. Where the latter outcome is predictable, the constructive-
knowledge rule would indeed fit the foreseeability model. But even if
it is inevitable that the officers will share their information, it is hardly
inevitable that the acting officer can predict that they will have
enough for probable cause, and therefore can act with that foreknowl-
edge. At best, the officer may guess that his colleagues have found
something helpful, and may act in the hope that their information will
provide the needed supplement.
Thus, on the one hand, constructive knowledge applies primarily
as an afterthought and largely resists the kind of integration and rou-
tinization that inevitable discovery permits, while on the other hand a
constructive-knowledge justification eliminates the § 1983 sanctions
that remain possible if exclusion is barred on inevitable-discovery
grounds. In short, the constructive-knowledge rule lacks a foreseeabil-
ity component and merely applies after the action to cleanse it of any
illegality.
Imputing unshared knowledge in this context also raises
problems of hindsight bias and confirmation bias—cognitive effects
that conspire in this instance to select the facts that ratify the officer’s
decision, even if those facts probably would not, and should not, have
police in a worse position than they would have been in if no unlawful con-
duct had transpired.”
L
A
F
AVE
,
supra note 8, § 11.4(a), at 276 (quoting Mark Paul Schnapp, Note, 5
H
OFSTRA
R
L. R
EV
. 137, 160 (1976))
. LaFave concludes that “[d]espite Nix, it is still true . . . that
the ‘inevitable discovery’ rule simply is inapplicable in those situations where its use
would, as a practical matter, operate to nullify important Fourth Amendment safe-
guards,” but he adds that “[t]he point is sometimes missed.” Id. at 271–72 (citing
People v. Stevens, 597 N.W.2d 53 (Mich. 1999)).
132 See supra notes 52–67 and accompanying text.
R
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1120 notre dame law review [vol. 82:3
governed his decision without the court’s aid.
133
Hindsight bias has
traditionally been an important concern in Fourth Amendment
law,
134
and it constitutes one of the primary motives for the warrant
requirement.
The thought is that a more accurate determination will occur if
the police must obtain it in advance from a neutral magistrate, who
will assess probable cause on the basis of a prediction, rather than
being influenced by the knowledge that the search was successful.
Moreover, the warrant commits the police to a certain state of knowl-
edge so that they may not amplify it later by recalling additional
details.
135
Therefore we encourage officers to obtain warrants, and
133 The rule also increases opportunities for police perjury. To validate an arrest,
police officers may be tempted to perjure themselves by claiming to have known
about details they did not observe until after the arrest. William Stuntz has noted that
critics of the evolving Fourth Amendment framework have been concerned about
both police perjury and hindsight bias, whereas the crafters of that framework have
been primarily concerned with the latter. Stuntz, supra note 57, at 914–15. The
R
emphasis on the risk of cognitive bias rather than deliberate misconduct may reflect
different assumptions about law enforcement officials, but this emphasis can also have
doctrinal effects. If a court’s hindsight bias makes a just-barely-impermissible search
appear justified, the precedent may help to marginally lower the probable-cause stan-
dard in future cases. By contrast, if a police officer perjures himself, he will probably
invent details that do not skate near the lower border but instead clearly satisfy the
standard. Insofar as Fourth Amendment doctrine takes seriously the problem of
hindsight bias but gives less attention to the problem of perjury, then, the probable-
cause standard, as reflected in case law, remains relatively stable. For further discus-
sion of perjury, see Orfield, supra note 19, at 100–14.
R
134 See, e.g., Beck v. Ohio, 379 U.S. 89, 96 (1964) (“[A]fter-the-event justification
for the . . . search [is] too likely to be subtly influenced by the familiar shortcomings
of hindsight judgment.”); see also Stuntz, supra note 57, at 884, 912 n.68 (noting that
R
some studies support the existence of hindsight bias among jurors in deciding
whether police behaved illegally). For a useful overview of the problem of hindsight
bias, see Scott A. Hawkins & Reid Hastie, Hindsight: Biased Judgment of Past Events After
the Outcomes are Known, 107
P
SYCHIATRIC
B
ULL
.
311 (1990). For a recent study sug-
gesting that hindsight bias does not significantly influence judges’ probable-cause
determinations, see Andrew J. Wistrich et al., Can Judges Ignore Inadmissible Informa-
tion? The Difficulty of Deliberately Disregarding, 153 U.
P
A
. L. R
EV
.
1251, 1313–22 (2005).
135 See 2
L
A
F
AVE
, supra note 8, § 3.2(d), at 47 (“[H]indsight may not be employed
R
in determining whether a prior arrest or search was made upon probable cause. . . .
[I]f [the action] was pursuant to a warrant, then the information to be considered is
that which was made available to the issuing magistrate before the warrant was
issued.”); Stuntz, supra note 57, at 917 (“[T]he [warrant] application process . . .
R
records the police officer’s account of what he knows prior to the search. In a war-
rant system concerned chiefly with police perjury, the best approach might be to
force the officer to give his account before the fact in a warrant affidavit, but then allow
full adversary litigation of the probable cause issue after the fact in a suppression hear-
ing.”); see also 2
L
A
F
AVE
,
supra note 8, §§ 3.1, 4.3 (noting that the Fourth Amendment
R
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2007] constructive knowledge 1121
courts give more deference to warrants than to warrantless determina-
tions. It has also been suggested that “inevitable discovery” cases raise
particularly serious concerns about hindsight bias.
136
Confirmation bias, on the other hand, has rarely been addressed
as a significant problem in Fourth Amendment law.
137
Confirmation
bias leads people to accentuate the positive thrust of evidence that
accords with their expectations or desires, and to minimize the thrust
of evidence to the contrary.
138
The implications for the issue of prob-
able cause are obvious: in any search for evidence to verify the hypoth-
esis that a particular suspect is guilty, officers are likely to focus on
evidence that confirms the hypothesis and to discount evidence that
undermines it.
At its most serious, such bias results in strained interpretations of
the available evidence and failure to take note of evidence that erodes
belief in the suspect’s guilt, incriminates someone else, or is simply
unaccountable under the preferred explanation. Identity-based
prejudices, particularly racial bias, often trigger confirmation bias,
and their implications for Fourth Amendment law have been widely
discussed.
139
Where those considerations are not relevant, however,
requires an “Oath or affirmation” to support a warrant); John E. Taylor, Using Suppres-
sion Hearing Testimony to Prove Good Faith Under United States v. Leon, 54 U
. K
AN
. L.
R
EV
.
155, 219-22 (2005) (explaining the significance of an oath and affirmation in
obtaining a warrant). On a related point, the Supreme Court recently held that even
if “[a warrant] application adequately describe[s] the ‘things to be seized,’ ” that will
not save “[a] warrant from its facial invalidity,” Groh v. Ramirez, 540 U.S. 551, 557
(2004). Otherwise, the Court noted, the warrant’s lack of particularity could “ ‘per-
mit[ ] officers to expand the scope of the warrant by oral statements [that] would
broaden the area of dispute between the parties in subsequent litigation.’” Id. at 556
(quoting Ramirez v. Butte-Silver Bow County, 298 F.3d 1022, 1027 (9th Cir. 2002)).
136 Brooks, supra note 128, at 123.
R
137 One of the few discussions of the issue appears in Lee Epstein, et al., The
Supreme Court During Crisis: How War Affects Only Non-War Cases, 80 N.Y.U. L
. R
EV
.
1,
51–62 (2005). The problem is addressed more often in the context of jury delibera-
tions. See, e.g., Chris William Sanchirico, Character Evidence and the Object of Trial, 101
C
OLUM
. L. R
EV
.
1227, 1248 (2001).
138 For a useful overview, see Raymond S. Nickerson, Confirmation Bias: A Ubiqui-
tous Phenomenon in Many Guises, 2
R
EV
. G
EN
. P
SYCHOL
. 175 (1998).
139 See, e.g., Developments in the Law—Race and the Criminal Process, 101
H
ARV
. L.
R
EV
.
1472 (1988); Sheri Lynn Johnson, Race and the Decision to Detain a Suspect, 93
Y
ALE
L.J. 214 (1983); Tracey Maclin, Race and the Fourth Amendment, 51
V
AND
. L. R
EV
. 333,
387 (1998); David Rudovsky, Law Enforcement by Stereotypes and Serendipity: Racial Profil-
ing and Stops and Searches Without Cause, 3
U. P
A
. J. C
ONST
. L.
296 (2001); Randall S.
Susskind, Race, Reasonable Articulable Suspicion and Seizure, 31
A
M
. C
RIM
. L. R
EV
.
327
(1994); Lisa Walter, Eradicating Racial Stereotyping from Terry Stops: The Case for an
Equal Protection Exclusionary Rule, 71
U. C
OLO
. L. R
EV
.
255 (2000); Lu-In Wang, Race as
Proxy: Racism and Self-Fulfilling Stereotypes, 53
D
E
P
AUL
L. R
EV
.
1013 (2004).
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1122 notre dame law review [vol. 82:3
there is no easy way to tell how seriously the problem of confirmation
bias affects criminal investigations.
The warrant requirement, in any case, does little to prevent con-
firmation bias, because selective use of the evidence and even selective
interpretation of the evidence are unlikely to register on the magis-
trate.
140
That result is not necessarily undesirable. Perhaps confirma-
tion bias plays a positive role on the whole, by sparing the police the
losses that might result from second-guessing themselves.
141
Further,
again putting aside the question of identity-based bias, it is not clear
that confirmation bias in criminal investigations can be reduced with-
out commensurately reducing the capture rate. Hindsight bias may
well play a role in the application of the “inevitable discovery” rule,
but confirmation bias raises less concern in that context, given that
the rule applies only when a search has already been completed and
the incriminating details have been identified.
142
The constructive-knowledge rule raises concerns about both
forms of cognitive bias, which converge in this situation to create an
especially difficult problem. Once an officer has made an arrest or
begun a search, hindsight bias increases the likelihood that other
officers will attach suspicious meanings to the evidence they saw, and
confirmation bias makes it likely that they will simply forget about any
evidence that vitiates probable cause or that erodes the significance
they now attach to the evidence.
Anyone familiar with the Brady problem will immediately recog-
nize the difficulty: just as officers may honestly forget that they have
acquired exculpatory information that must be turned over to the
140 If vitiating evidence was available and the police did not disclose that when
they sought a warrant, and if the defense gets that information, it may be relevant to a
Brady claim, but again confirmation bias often reflects attitudes that are not fully con-
scious. That does not mean that all of its effects will be reasonable, and so it may lead
to Brady violations and may justify exclusion and even § 1983 liability, but those
results are not very likely.
141 See, e.g.,
G
ERD
G
IGERENZER
& P
ETER
M. T
ODD
, S
IMPLE
H
EURISTICS
T
HAT
M
AKE
U
S
S
MART
3–5 (1999) (discussing “fast and frugal heuristics”). For an application of this
research in the Fourth Amendment context, see Craig S. Lerner, Reasonable Suspicion
and Mere Hunches (George Mason Univ. Sch. of Law, Law & Economics, Working
Paper No. 05–209, 2005) available at http://ssrn.com/abstract=840258.
142 There still remains some room for confirmation bias: as to the hypothetical
lawful search that would “inevitably” have occurred later, the question is whether it
would have had the same scope as the illegal search. There must be a persuasive
argument not only that the lawful search would have taken place, but also that it
would have uncovered the evidence seized during the unlawful search. Both hind-
sight and confirmation bias may influence that determination.
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2007] constructive knowledge 1123
defense,
143
here similarly the incriminating information is likely to
occupy their attention, and the facts that tend in the other direction
may be overlooked. Thus the event of the arrest itself may invest the
probable-cause determination with the force of a duly formulated
decision, thus increasing the likelihood that the police will recall their
various observations only with an eye to the details that support proba-
ble cause.
But the point of a criminal investigation is not simply to develop
probable cause, as if more were better, but rather to use probable
cause as a step towards convicting guilty persons. Whereas the collec-
tive-knowledge rule takes a probable-cause determination that has
already been fashioned on the basis of an officer’s full awareness of
the facts, the constructive-knowledge rule may aid in the manufacture
of probable cause, creating constructive probable cause when, absent
the operation of these cognitive biases, objective probable cause is
lacking.
This problem has only been exacerbated by the limited case law
addressing the issue. The Second Circuit—the only court to weigh in
thus far—has held that the imputation rule covers inculpatory infor-
mation but not exculpatory information. In Savino v. City of New
York,
144
a § 1983 suit in which a former city employee alleged false
arrest, the court stated that “the [collective-knowledge] doctrine has
traditionally been used to assist officers in establishing probable
cause—not to impute bad faith to one member of an enforcement
team on the basis of another member’s knowledge.”
145
The court added that “this doctrine cannot be used to impute to
an officer ‘facts known to some [other] members of the police force
which exonerate an arrestee.’”
146
The holding of Savino may be
143 See, e.g., Kyles v. Whitley, 514 U.S. 419, 438 (1995) (“[N]o one doubts that
police investigators sometimes fail to inform a prosecutor of all they know,” but the
prosecution is nevertheless “held accountable under Bagley and Brady for evidence
known only to police investigators and not to the prosecutor.”).
144 331 F.3d 63 (2d Cir. 2003).
145 Id. at 74 (emphasis added); see also Urbanique Prod. v. City of Montgomery,
428 F. Supp. 2d 1193, 1216 (M.D. Ala. 2006) (dismissing plaintiff’s § 1983 claim alleg-
ing false arrest; even though arresting officer lacked incriminating information about
suspect, another officer had such information, and the two officers “were working in
‘close concert’ on the investigation. . . . [T]hus, [the second officer’s] knowledge is
imputed to [the arresting officer], regardless of whether at the time of the arrest [the
latter] had actual knowledge of all the facts.”).
146 Savino, 331 F.3d at 74 (quoting United States v. Valez, 796 F.2d 24, 28 (2d Cir.
1986)). Savino purports to summarize the holding of Valez, but in fact misrepresents
that decision. In Valez, the defendant was mistakenly arrested on the instruction of an
officer who gave a vague description of the suspect; within minutes after Valez was
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1124 notre dame law review [vol. 82:3
appropriate in the context of a § 1983 suit, because liability under that
statute does not allow for imputation but looks only to the knowledge
and conduct of the individual defendant.
147
But Savino expresses that
conclusion in language that pronounces on the imputation rule
generally.
As regards the ordinary suppression case (rather than a § 1983
case), Savino’s analysis is inconsistent with the premise of the con-
structive-knowledge rule. The rule treats a number of individuals as if
they were simply a communal body—and in that case, their commu-
nal mind should take account of the same details that an individual
would consider, including the details that support belief of guilt and
those that undermine it.
The “inevitable discovery” premise reflects a view of police work
that might be illustrated heuristically by imagining a probable-cause
machine, a portable computer with audiovisual capabilities that can
methodically detect, record, catalogue, and cross-reference all rele-
vant information and that issues an alert when that information
amounts to probable cause.
148
With this machine, information trans-
fer is frictionless and practically free.
149
To say that the constructive-
knowledge cases ultimately depend on such a vision is to show why the
“inevitable discovery” rule has so much explanatory force in this con-
text. Information transfer is relatively costless when officers are work-
ing jointly on an investigation. After all, one of the main reasons for
assigning a team of officers to work together on a search or arrest is to
make it easier and faster to collect information.
mistakenly arrested (and was found to possess contraband), the officer who issued the
instruction found and arrested the person he was seeking. Valez, 796 F.2d at 25–26.
Valez argued that that officer’s knowledge should have been imputed to the one who
arrested him, rendering his arrest illegal. Id. at 27. The court rejected the argument
that “facts known to some members of the police force which exonerate an arrestee
are ipso facto imputed to the arresting officer. Rather, the issue is whether the failure
to communicate those facts to the arresting officer rendered the mistaken arrest
unreasonable.” Id. at 28 (emphasis added). Rather than generally barring the imputa-
tion of any “facts known to . . . members of the police force which exonerate an
arrestee,” as Savino would have it, Valez merely held that under the circumstances of
that case, the exculpatory information could not be imputed. Id.
147 See Monell v. Dep’t of Soc. Servs., 436 U.S. 658, 691–95 (1978).
148 For a variant on this image, see Daniel J. Solove, Privacy and Power: Computer
Databases and Metaphors for Information Privacy, 53
S
TAN
. L. R
EV
. 1393 (2001). Solove’s
concerns about privacy are relevant here because the probable-cause machine would
have to be linked to various other databanks so that information registered at the
investigation scene could be cross-checked.
149 Except, of course, for the cost of the machine itself and periodic upgrades.
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2007] constructive knowledge 1125
But it does not follow that information transfer will always occur
efficiently, or that it will even occur at all. In some cases there will be
a communications failure, and in others an officer will simply fail to
grasp the significance of some vital detail, and so will fail to pass her
observations along to anyone else. Moreover, in some law enforce-
ment situations, information transfer is difficult, friction-laden, and
expensive. Finally, the image of the computer lends an air of preci-
sion and infallibility to the analysis of the data, whereas human analy-
sis involves the risks of cognitive bias discussed above. “Inevitable
discovery” may help to justify some of the constructive-knowledge
cases, but it cannot justify them all.
Even if it were possible to identify the cases in which the police
would have conferred, and even if the imputation rule could
reproduce the result of that conference without any cognitive error,
some cases would remain that could not be explained by resort to
“inevitable communication.” If an officer conducts a search or arrest
when probable cause is neither present nor imminent, he is in the
same position as an officer acting by himself. Consider the case of an
officer who conducts an illegal detention and, while it is under way,
acquires probable cause to search from another source—for example,
by running a warrant check. This newly acquired information cannot
be used to legitimate the search.
150
That the officer actually obtained
incriminating information does not convert an invalid detention into
a valid one.
Rather than resort to imputation in these cases, courts have said
that “[t]he search was either good or bad at its inception. It does not
change character by fortuitous events which occur while the search is
underway.”
151
Analogously, in the constructive-knowledge context, if
communication among officers is not “inevitable,” imputation cannot
be justified by positing a hypothetical event which, had it occurred at
all, would have been merely fortuitous. However, while that answer
may identify the problem with the officer’s action, it fails to address
what is noteworthy about the role of the collectivity in the construc-
150 See, e.g., Moreno v. Baca, 431 F.3d 633, 641 (9th Cir. 2005) (finding that deten-
tion on insufficient cause was not legitimated by the discovery that the suspect was a
parolee in violation of the terms of his release, because “police officers cannot retro-
actively justify a suspicionless search and arrest on the basis of an after-the-fact discov-
ery of an arrest warrant or a parole condition”); United States v. DiCesare, 765 F.2d
890, 899 (9th Cir. 1985) (“[T]he acquisition of probable cause during an unlawful
seizure does not cure the illegality and does not constitute an independent source of
probable cause.”).
151 State v. Carter, 267 N.W.2d 385, 387 (Iowa 1978).
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1126 notre dame law review [vol. 82:3
tive-knowledge analysis—an issue that touches on questions involving
administrative law. I now turn to that subject.
III. P
ROBABLE
-C
AUSE
A
NALYSIS AND
A
DMINISTRATIVE
D
ECISIONMAKING
Like police departments, administrative agencies often reach
decisions collectively. The value of an agency’s analysis may be pre-
mised on the agents’ collective expertise, and the more formally the
agency presents the opinions of its experts and the bases for their con-
clusions, the more likely the agency will prevail if its regulations are
challenged. Far from excusing agencies from failing to pool informa-
tion, we require them to do so if they hope to receive deference for
their decisions.
Agency regulations also bear some similarity to probable-cause
determinations. In endorsing the collective-knowledge rule in the
1960s, the courts promoted the same values that are often at stake in
judicial review of administrative decisionmaking. We have seen that
courts do not require more process, more bureaucratic review, if the
less formal procedure is deemed to reflect sufficient sensitivity to the
Fourth Amendment balance.
152
In the administrative context, we find
a similar trade-off between procedure and results.
As to results, courts are averse to administrative regulations that
either impose heavier costs on the regulated entities than the author-
izing legislation reasonably permits, or that fail to constrain those enti-
ties as contemplated in the authorizing legislation.
153
As to process,
courts are averse both to administrative procedural laxity that delivers
regulations without sufficient formality,
154
and to excessively fastidious
152 See supra notes 37–45 and accompanying text.
R
153 See, e.g., Whitman v. Am. Trucking Ass’ns, Inc., 531 U.S. 457, 467 (2001) (hold-
ing that the EPA could not consider implementation costs when setting air quality
standards).
154 See, e.g., Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S.
29, 43 (1983) (reviewing court must be satisfied that agency has “examine[d] the
relevant data and articulate[d] a satisfactory explanation for its action”); Citizens to
Pres. Overton Park, Inc. v. Volpe, 401 U.S. 402, 416 (1971) (stating that the reviewing
court must conduct a “searching and careful” inquiry to determine “whether the
[agency’s] decision was based on a consideration of the relevant factors”); see also
Jerry L. Mashaw & David L. Harfst, Regulation and Legal Culture: The Case of Motor
Vehicle Safety, 4
Y
ALE
J.
ON
R
EG
.
257, 279 (1987) (discussing judicial review of the
National Highway Traffic Safety Administration’s regulations); Thomas O. McGarity,
Some Thoughts on “Deossifying” the Rulemaking Process, 41
D
UKE
L.J
. 1385, 1387 (1992)
(arguing that agency rulemaking has lost its efficiency advantages due to tougher pro-
cedural standards of judicial review); Martin Shapiro, APA: Past, Present, Future, 72
V
A
.
L. R
EV
.
447, 477 (1986) (discussing the additional rules imposed by courts on agen-
cies in the 1960s and 1970s to require more comprehensive fact records for stricter
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2007] constructive knowledge 1127
procedural requirements that would make it too costly for administra-
tive agencies to craft appropriate regulations.
155
In short, judicial
review of administrative decisionmaking strives for a balance with
respect to the extent of the regulations and also the amount of pro-
cess required to produce them.
Viewed through the lens of administrative law, probable-cause
determinations may be likened to agency decisions, and the general
public may be likened to the regulated entity. Like the Food and
Drug Administration and the Department of Health and Human Ser-
vices, law enforcement departments are executive branch agencies.
But whereas those other agencies are delegated the authority to inter-
pret legislation and to promulgate regulations accordingly, neither
local police departments nor federal law enforcement agencies are
normally regarded as having the authority to issue interpretations of
the Fourth Amendment.
156
Nevertheless, police departments have to instruct officers on what
constitutes probable cause, and individual officers have to apply those
instructions on a daily basis. These guidelines must necessarily offer
interpretations of the probable-cause standard that will be applied
during encounters with members of the public, at least until a court
rejects that interpretation.
Similarly, police departments often address local law-enforce-
ment concerns by crafting and implementing large-scale programs
that incorporate the department’s understanding of what is permissi-
ble under the Fourth Amendment.
157
Such a program’s architecture,
judicial review); Matthew C. Stephenson, A Costly Signaling Theory of Hard Look Review
(John M. Olin Ctr. for Law, Econ. & Bus., Harvard Law Sch., Discussion Paper No.
539, 2006), available at http://papers.ssrn.com/abstract=921421 (proposing that
courts impose explanation requirements on agency action to alleviate the differences
in expertise between regulators and the judges reviewing their action).
155 See, e.g., Vt. Yankee Nuclear Power Corp. v. Natural Res. Def. Council, Inc.,
435 U.S. 519, 525 (1978) (rejecting procedural requirements imposed by the D.C.
Circuit and explaining that the Court of Appeals had “engraft[ed] [its] own notions
of proper procedures upon agencies entrusted with substantive functions by
Congress”).
156 See, e.g., Erwin Chemerinsky, In Defense of Judicial Review: A Reply to Professor
Kramer, 92
C
AL
. L. R
EV
.
1013, 1021 (2004) (doubting that “we [would] really feel
secure giving police officers the power to define what is a constitutionally appropriate
search with only the security of knowing that their actions may someday be reviewed
by a police chief who may someday be called to task by a mayor who was elected by the
people”).
157 See, e.g., City of Chicago v. Morales, 527 U.S. 41, 48 (1999) (holding unconsti-
tutional the City of Chicago’s Gang Congregation Ordinance where limitations on the
discretion police had to enforce the ordinance were left to police policy rather than
placing such limitations in the ordinance itself).
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1128 notre dame law review [vol. 82:3
including the specification as to what suffices to justify a stop, frisk, or
pat-down, and what investigatory options are available absent any basis
for suspicion, does not reflect the assessment of a particular officer,
formed as events are unfolding during an investigation. Instead, like
the rest of the plan, the decision about whom to stop and on what
cause is formulated and specified in advance. For example, the suspi-
cionless traffic stops in Indianapolis v. Edmond
158
—ultimately declared
unconstitutional by the Supreme Court—involved roadblocks at
which the police followed a routine set out in “written directives
issued by the chief of police.”
159
Under these procedures, the officers
would “stop a predetermined number of vehicles,” approach each
vehicle to tell the driver “that he or she [was] being stopped briefly at
a drug checkpoint, . . . ask[ ] the driver to produce a license and regis-
tration,” and “look[ ] for signs of impairment and conduct[ ] an
open-view examination of the vehicle from the outside.”
160
The
instructions required the officers to “conduct each stop in the same
manner until particularized suspicion develop[ed],” and gave the
police “no discretion to stop any vehicle out of sequence.”
161
“[C]heckpoint locations [were] selected weeks in advance based on
such considerations as area crime statistics and traffic flow.”
162
As this detailed protocol shows, the plan was devised with the
expectation that it would not offend equal protection or Fourth
Amendment principles because it required officers to treat all drivers
alike. The plan reflects a policy presumably applying a departmen-
tally shared view of Fourth Amendment requirements.
163
Thus, it would be misleading to say that the police may not create
policies based on interpretations of the Fourth Amendment; the
police department must issue such rules all the time. But in so doing,
the department is not filling in gaps pursuant to a legislative mandate,
or acting under a delegated power. The police department has no
authority to devise interpretations of the probable-cause standard or
to issue directives telling the public how to conform to Fourth Amend-
158 531 U.S. 32 (2000).
159 Id. at 35.
160 Id.
161 Id.
162 Id.
163 For another example, see Lynn Sweet, Clinton Unveils Tailored 7-Point Sweeps
Policy,
C
HI
. S
UN
-T
IMES
, Apr. 17, 1994, at A3 (describing a program developed jointly
by the Chicago Police Department and the residents in a Chicago public housing
project, under which the police would engage in warrantless searches to stop violent
crime in the area; the program was declared unconstitutional by Judge Wayne
Anderson).
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2007] constructive knowledge 1129
ment requirements; instead, the police apply rulings that come from
the courts. The interpretive work that the department performs
involves translating a judicial pronouncement into its practical appli-
cation, implementing the legal standard and thereby testing its
boundaries.
164
Whatever deference an officer’s probable-cause determination
merits, then, it cannot be analogous to Chevron deference, which
applies only “[i]f Congress has explicitly left a gap for the agency to
fill, [so that] there is an express delegation of authority to the agency
to elucidate a specific provision of the statute by regulation.”
165
In
United States v. Mead Corporation,
166
the Supreme Court discussed the
bases for giving deference to more mundane administrative decisions,
involving the implementation of regulations rather than their issu-
ance under legislative authority. Mead considered the Treasury
Department’s issuance of ruling letters specifying tariffs on imported
merchandise.
167
Such determinations, authorized under a customs
regulation that in turn was promulgated under statutory authority, at
that time were not governed by the notice-and-comment require-
ments of section 553 of the Administrative Procedure Act, and did not
carry the force of law in the sense of constituting an official policy
announcement that specifies the rights and obligations of parties
other than the letter’s recipient.
168
A ruling letter articulates “the official position of the Customs
Service with respect to the particular transaction or issue described
therein,”
169
and thus, like a decision to search or arrest (or to send
out a bulletin instructing officers to take such action), it represents an
agency official’s decision about how to apply the law in a specific case.
As with probable-cause determinations, large numbers of ruling let-
ters are produced annually—“46 different Customs offices issue
10,000 to 15,000 of them each year.”
170
Like probable-cause determi-
nations, then, such decisions must be produced quickly and repeat-
edly, and while experience may make the agency officials proficient in
164 See, e.g., Michael S. Ariens, Constitutional Law and the Myth of the Great Judge, 25
S
T
. M
ARY
’
S
L.J. 303, 311 (1993) (“The value of . . . the Fourth Amendment’s require-
ment of the existence of probable cause before engaging in a search or seizure,
depends upon the police officers who implement [this] constitutional rule[ ].”).
165 Chevron U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 843–44
(1984).
166 533 U.S. 218 (2001).
167 Id. at 221–24.
168 See id. at 226.
169 Id. at 222 (quoting 19 CFR § 177.9 (2000)).
170 Id. at 233.
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1130 notre dame law review [vol. 82:3
applying the legal standards, the rapid-fire pace of the process may in
some instances produce inconsistent and even unacceptable
outcomes.
In considering what level of deference to accord a ruling letter,
the Court observed that “whether or not they enjoy any express dele-
gation of authority on a particular question, agencies charged with
applying a statute necessarily make all sorts of interpretive choices,”
which may merit some deference given the agency’s “body of experi-
ence and informed judgment.”
171
The Court thus recognized that the
practical application of a statute, like the gap-filling activity of clarify-
ing a broad statutory mandate, requires interpretation, and that those
interpretive decisions may be entitled to some deference. Mead
added that relevant concerns in such a case include “the degree of the
agency’s care, its consistency, formality, and relative expertness,
and . . . the persuasiveness of the agency’s position.”
172
Taken together, these factors emphasize two basic considerations:
the experience of the decisionmakers and the value of the deliberative
process. Consistency and expertness may be products of experience
alone (a well-seasoned bureaucrat may be familiar enough with the
regulations to apply them quickly, evenly, and proficiently), but care
and formality seem to speak to the agency’s procedural virtues, its
ability to review an array of alternatives and to consider the merits of
each before reaching a decision. Persuasiveness, understood as
embracing rationality and attentiveness to context, is not so much a
separate category as an attribute of the other two considerations.
173
Mead enumerated these considerations in the context of an
agency’s “administ[ration of] its own statute,” but they might also
apply to an agency’s application of a standard developed by another
authority.
174
Notably, the treatment of experience and deliberation as
proper bases for deference is already well established in Fourth
Amendment law.
In judicial review of probable-cause determinations, as in admin-
istrative law, deference is doled out according to a two-tier hierarchy,
171 Id. at 227 (quoting Bragdon v. Abbott, 524 U.S. 624, 642 (1998)).
172 Id. at 228 (footnotes omitted).
173 See, e.g., United States v. E.I. Dupont de Nemours & Co., 432 F.3d 161, 177 n.17
(3d Cir. 2005) (“[T]he persuasiveness of the government’s position rests on the ‘spe-
cialized experience’ the EPA brings to bear on the issue of CERCLA enforcement.”
(citing Mead, 533 U.S. at 235)); Wilderness Soc’y v. U.S. Fish & Wildlife Serv., 316
F.3d 913, 922 (9th Cir. 2003) (approving appellee’s decision “because of its persua-
siveness. The Service has considered the issue thoroughly. Its reasoning is not
unsound. The Service had adequate information . . . .”).
174 Mead, 533 U.S. at 228.
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defined by the degree of formality in the decisionmaking process. On
the one hand, if the police have filed an affidavit and have been given
a warrant, the magistrate’s imprimatur is afforded “great defer-
ence,”
175
akin to the “substantial deference”
176
due under Chevron.
177
Indeed, until the Supreme Court explained in the 1960s that a war-
rant is entitled to “substantial deference,” some courts regarded the
probable-cause determination underlying a warrant as virtually
unreviewable.
178
175 Ornelas v. United States, 517 U.S. 690, 698 (1996); United States v. Leon, 468
U.S. 897, 914 (1984) (quoting Spinelli v. United States, 393 U.S. 410, 419 (1969)); see
also United States v. Riccardi, 405 F.3d 852, 860 (10th Cir. 2005) (“Where the search
or seizure was pursuant to a warrant, our review of the issuing magistrate’s finding of
probable cause is very deferential . . . .”); United States v. Ribeiro, 397 F.3d 43, 48 (1st
Cir. 2005) (“In reviewing the affidavit supporting an application for a search warrant,
we give significant deference to the magistrate judge’s initial evaluation . . . .”).
176 Gonzales v. Oregon, 126 S. Ct. 904, 914 (2006).
177 Chevron U.S.A., Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837 (1984).
178 Early decisions on the degree of deference accorded to a warrant generally
characterize the finding of probable cause as “conclusive” and either unappealable or
appealable only if completely unsupportable. See, e.g., Rettich v. United States, 84
F.2d 118, 121 (1st Cir. 1936) (“[T]he commissioner’s findings as to probable cause
are conclusive, unless it is shown to the contrary.” (citation omitted)); Gracie v.
United States, 15 F.2d 644, 646 (1st Cir. 1926) (holding that the commissioner’s find-
ing is “conclusive” unless authority to issue warrant was “arbitrarily exercised”); State
v. Friend, 220 N.W. 59, 61 (Iowa 1928) (“[The magistrate’s] finding is conclusive”);
Commonwealth v. Leddy, 105 Mass. 381, 383 (1870) (holding that the magistrate’s
decision “is not subject to appeal, and must be regarded as conclusive, unless it
appears to be utterly groundless”); see also United States v. Greene, 108 F. 816, 819
(S.D.N.Y. 1901) (“[As to] the existence of probable cause to believe that an offense
has been committed, . . . . the question upon review never is whether the proof was
such as would be required to convict the accused upon a trial by jury; but only as to
the existence of any legal evidence before the commissioner upon which he might
find that there was reasonable cause to believe that the crime has been committed.”
(emphasis added)); William W. Greenhalgh & Mark J. Yost, In Defense of the “Per Se”
Rule: Justice Stewart’s Struggle to Preserve the Fourth Amendment’s Warrant Clause, 31
A
M
.
C
RIM
. L. R
EV
. 1013, 1041 n.154 (1994) (“Although early interpretations of the Fourth
Amendment may have been scant, interpretations of the state constitutions and state
practice under the common law lend . . . support to the view that the existence of a
warrant was the primary criterion in determining whether a search was reasonable.”
(citing Commonwealth v. Dana, 2 Mass. (2 Met.) 329, 336 (1841); Bell v. Clapp, 10
Johns. 263, 264 (N.Y. 1813); Wakely v. Hart, 6 Binn. 315, 318 (Pa. 1814))); Steven M.
Kipperman, Inaccurate Search Warrant Affidavits as a Ground for Suppressing Evidence, 84
H
ARV
. L. R
EV
. 825, 830 (1971) (“[S]ome courts still adhere to the view that the magis-
trate’s or commissioner’s ruling on probable cause is final . . . .” (footnote omitted)).
The cases cited by Greenhalgh and Yost speak to the importance of obtaining a war-
rant, but do not address the standard for challenging a warrant for lack of probable
cause.
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1132 notre dame law review [vol. 82:3
Arguably, the warrant—sometimes required and otherwise pre-
ferred—is the analogue in criminal procedure to the notice-and-com-
ment process that triggers Chevron deference. The Supreme Court
has explained that “the detached scrutiny of a neutral magistrate . . . is
a more reliable safeguard against improper searches than the hurried
judgment of a law enforcement officer ‘engaged in the often competi-
tive enterprise of ferreting out crime.’”
179
The magistrate’s review
ensures that the evidence will receive “serious and independent
consideration.”
180
To be sure, such a procedure hardly approximates one that pub-
licizes the proposal, solicits an array of views from all sides, and weighs
their respective merits before arriving at a conclusion. As with a
grand jury proceeding, the most interested adverse party has no
opportunity to participate. But a warrant does require the police to
list facts and to explain their significance in a way that will persuade a
disinterested observer. To that extent, the requirement of a formal
justification for a search or arrest serves the same goal as an adminis-
trative procedure “designed to assure due deliberation.”
181
If the hur-
ried and potentially self-serving judgment of the police is unreliable,
the magistrate’s deliberation may be more objective.
Moreover, the notice-and-comment process reflects some of the
same concerns underlying the warrant requirement, albeit not with
the same emphasis. As noted earlier, the use of a warrant protects
against hindsight bias and the risk of police perjury, but does little to
prevent confirmation bias.
182
These same concerns figure in adminis-
trative law, but in the opposite order. Soliciting public comments
helps to combat confirmation bias, which might otherwise pose seri-
ous problems for bureaucrats issuing regulations that have significant
effects on markets and affect even more people indirectly.
183
These
problems may be even more severe in cases of excessive interest-group
influence or agency capture, which are generally not regarded as sig-
nificant problems in criminal law enforcement.
184
179 United States v. Chadwick, 433 U.S. 1, 9 (1977) (quoting Johnson v. United
States, 333 U.S. 10, 14 (1948)).
180 McCommon v. Mississippi, 474 U.S. 984, 987 (1985) (Brennan, J., dissenting)
(noting his objection to denial of certiorari).
181 Smiley v. Citibank (South Dakota), 517 U.S. 735, 741 (1996).
182 See supra notes 133–42 and accompanying text.
R
183 On problems of confirmation bias in administrative law, see, for example,
Richard W. Murphy, Judicial Deference, Agency Commitment, and Force of Law, 66
O
HIO
S
T
. L.J.
1013, 1058–59 (2005), and Mark Seidenfeld, Cognitive Loafing, Social Conform-
ity, and Judicial Review of Agency Rulemaking, 87
C
ORNELL
L. R
EV
.
486, 504–05 (2002).
184 See, e.g., Rachel E. Berkow, Administering Crime, 52 UCLA L.
R
EV
. 715, 725–26
(2005) (noting that criminals—the group most directly affected by sentencing regula-
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2007] constructive knowledge 1133
As to perjury, the analogous problem in administrative law
involves “post hoc rationalizations”
185
invented in the course of litiga-
tion to repair an agency’s failure to defend its decision earlier. To the
extent that the agency articulates a rationale to accompany its deci-
sion, after having reviewed the public comments, that rationale pro-
vides a contemporaneous justification and thereby forestalls the
objection that the agency has acted first and then cast about for an
explanation.
Finally, by contrast with the Fourth Amendment context, hind-
sight bias is not a significant concern in judicial review of administra-
tive decisions. The fact that a search yielded contraband may unduly
influence a court to view the search as permissible, but courts regard
themselves as entirely capable of evaluating an administrative regula-
tion ex ante, as of course they review most actions. While the justifica-
tions for the notice-and-comment process are treated in a tellingly
different fashion from those for the warrant requirement, the degree
of procedural formality is similar.
On the other hand, if there has been no formal preclearance pro-
cess, the determination of probable cause receives comparatively little
deference, as in Mead.
186
Even under Mead, however, as noted above,
an agency’s determination may be entitled to some deference if the
tions—are “in a poor position to mobilize to fight” and “cannot easily self-identify in
advance”).
185 See, e.g., Bowen v. Georgetown Univ. Hosp., 488 U.S. 204, 212–13 (1988)
(“‘The courts may not accept appellate counsel’s post hoc rationalizations for agency
[orders,]’ [particularly where counsel’s] current interpretation . . . is contrary to
the . . . view of [the same] provision advocated in past cases . . . . Deference to what
appears to be nothing more than an agency’s convenient litigating position would be
entirely inappropriate.” (quoting Burlington Truck Lines, Inc. v. United States, 371
U.S. 156, 168 (1962))); cf. Auer v. Robbins, 519 U.S. 452, 462 (1997) (noting that
agency’s position was “in no sense a ‘post hoc rationalizatio[n]’ ” and therefore was not
“unworthy of deference,” where it was advanced for the first time in a brief but did
not contradict any previous position taken by the agency and stating “[t]here is simply
no reason to suspect that the interpretation does not reflect the agency’s fair and
considered judgment on the matter in question”).
186 United States v. Mead Corp., 533 U.S. 218, 229–31 (2001). Arguably, all proba-
ble-cause determinations, including those supported by a warrant, should be analo-
gized to ruling letters of the sort addressed in Mead. The Court observed that some
ruling letters are accompanied by the agency’s own explanation of its rationale, and
accordingly deserve more deference: “Most ruling letters contain little or no reason-
ing, but simply describe goods and state the appropriate category and tariff. A few
letters, like the . . . ruling at issue here, set out a rationale in some detail.” Id. at 224.
However, as discussed in Part II, a magistrate’s approval makes a warrant into more
than just a decision accompanied by the agency’s explanation: it makes the warrant
into a decision that has been certified by a neutral decisionmaker outside of the
agency seeking approval for its action.
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1134 notre dame law review [vol. 82:3
decision involves technical or complex issues about which the agency
has expertise. Analogously, in a court’s analysis of probable cause, an
officer’s “experience and expertise” may merit some deference.
187
In the ordinary case, then, review of a warrantless search or arrest
finds a counterpart in Mead’s consideration of the decisionmaker’s
proficiency, but not in Mead’s concern with care and formality. This
makes perfectly good sense, because in the ordinary case, the condi-
tions giving rise to a warrantless arrest (e.g., exigent circumstances,
automobile searches, searches incident to arrest) leave little room for
care and formality.
188
Such quintessentially bureaucratic virtues play an important role
in review of administrative decisionmaking, whereas making determi-
nations of probable cause is not a bureaucratic exercise but more
often a decision that must be made quickly, under pressure, and with
a risk of personal danger. This is not to say that caution and thor-
oughness have no place when an officer pursues a suspect after seeing
a possible criminal act or receiving a call for backup; it is only to say
that when courts evaluate probable cause, they take those circum-
stances into consideration and give the officer some room for
error.
189
187 See, e.g., City of Chi. v. Morales, 527 U.S. 41, 109–10 (1999) (Thomas, J., dis-
senting) (“[W]e trust officers to rely on their experience and expertise in order to
make spur-of-the-moment determinations about amorphous legal standards such as
‘probable cause’ and ‘reasonable suspicion . . . .’”); Ornelas v. United States, 517 U.S.
690, 700 (1996) (“[A] police officer may draw inferences based on his own experi-
ence in deciding whether probable cause exists.”); United States v. Barth, 288 F.
Supp. 2d 1021, 1031 (D.N.D. 2003) (“Courts are to give deference to the experience
and expertise of law enforcement officers in determining whether certain conduct is
suspicious.” (citing Ornelas, 517 U.S. at 700)); United States v. Rogers, 53 F.2d 874,
876 (D.N.J. 1931) (“In determining probable cause, . . . the experience and skill of
the officers . . . must be taken into account.”).
188 In the case of consent, on the other hand, the police often answer the need for
formality by obtaining a signature on a consent form. See, e.g., Pa. Bd. of Prob. &
Parole v. Scott, 524 U.S. 357, 379 (1998); Cleary v. Bolger, 371 U.S. 392, 393 (1963);
In re Fried, 161 F.2d 453, 454–55 (2d Cir. 1947).
189 See, e.g., Maryland v. Pringle, 540 U.S. 366, 371 (2003) (“‘Finely tuned stan-
dards such as proof beyond a reasonable doubt or by a preponderance of the evi-
dence, useful in formal trials, have no place in the [probable-cause] decision.’”
(quoting Illinois v. Gates, 462 U.S. 213, 235 (1983))); Illinois v. Rodriguez, 497 U.S.
177, 196 (1990) (Marshall, J., dissenting) (“[P]robable cause [is] not absolute cer-
tainty . . . . [T]he possibility of factual error is built into the probable cause standard,
and such a standard, by its very definition, will in some cases result in the arrest of a
suspect who has not actually committed a crime. . . . [A] search is reasonable under
the Fourth Amendment whenever that standard is met, notwithstanding the possibil-
ity of ‘mistakes’ on the part of police.” (quoting Brinegar v. United States, 338 U.S.
160, 176 (1949))).
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2007] constructive knowledge 1135
The Court’s list of factors potentially justifying deference in
Mead, then, points to a relatively high threshold for deference in that
context, whereas the Court has not felt compelled to produce a check-
list of factors guiding the degree of deference for warrantless searches
and arrests, but instead has said that the evaluation depends on the
totality of the circumstances and has been content to treat the
officer’s expertise as one of the factors.
190
Practically, the deference
due just for an officer’s expertise may go a long way towards validating
a search,
191
whereas deference based on “expertise” alone, without
the other factors, might well be insufficient to justify upholding an
administrative determination.
192
Even if the considerations are simi-
lar in both contexts, the level of deference is not the same, because
the threshold for upholding a search or arrest is lower.
Nevertheless, some probable-cause determinations do occur in
more bureaucratic settings. Most obviously, when preparing an affida-
vit to accompany a warrant request, an officer will review her notes to
ensure that she has described the evidence properly and has included
enough to satisfy the probable-cause requirement—and if she is part
of an investigative team, she will also review information collected by
her colleagues. In an ongoing investigation, as evidence comes in,
those assigned to the case will confer periodically to evaluate the state
of the evidence and to agree on whether they have enough to
proceed.
Though perhaps far from the typical collective-knowledge case,
these scenarios are not far from the typical constructive-knowledge
case. By imputing unshared information in those cases, the courts
treat the police as if they had conferred and agreed on a decision—
perhaps not with the same care and formality that Mead describes, but
at least with more care and formality than can be attributed to the
officer who acts alone under pressure.
The rule bestows the status of a decision on a conclusion that
never had the benefit of the decisionmaking process. If a discussion
190 See supra note 187 and accompanying text.
R
191 See, e.g., United States v. Santos, 403 F.3d 1120, 1124–25 (10th Cir. 2005) (not-
ing that although “appellate review of whether an officer had reasonable suspicion [is
conducted] ‘de novo,’” the evidence must be in viewed in the light most favorable to
the determination of the district court and with consideration of the officer’s experi-
ence and training, so that “[i]n practice, this looks more like deference—indeed,
double deference—than de novo review”).
192 Indeed, in Mead, on remand, the Federal Circuit rejected Customs’ analysis,
283 F.3d 1342 (Fed. Cir. 2002), even though the Supreme Court had noted that the
ruling letter in question “set out a rationale in some detail,” unlike the typical ruling
letter, which “contain[s] little or no reasoning,” 533 U.S. 218, 224 (2001).
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1136 notre dame law review [vol. 82:3
among the officers was imminent in any case, the rule in effect
backdates that event to upgrade the degree of formality associated
with the acting officer’s decision—and so if that condition is lacking,
the rule creates formality where none would have existed.
That the constructive-knowledge rule thus diminishes the need
for deliberation is paradoxical because the rule’s very premise has
been that the police operate like an administrative agency in these
cases. Characterizing a police team as a “single unit” or “corporate
body,” as some courts have done,
193
emphasizes that the police are
working jointly on a shared problem with the benefits that such joint
action creates, such as information-pooling and the improved accu-
racy that results from peer review.
There is a large body of research suggesting that organizations
“think” differently from individuals, developing special routines for
transmitting, analyzing, and acting on new information.
194
But those
models involve actual exchange of information, and do not suggest
that unshared knowledge or analysis may be imputed among team
members.
Thus the constructive-knowledge rule does not, as a general mat-
ter, lower information-gathering costs while leaving the Fourth
Amendment equilibrium intact. The cost of formal deliberative pro-
cedures in the administrative context may be relatively high, and so it
makes sense that when the authorizing legislation does not expressly
require such deliberation, courts allow agencies to decide how to allo-
cate time and personnel to make their production of regulations
more efficient. If the agency has taken care, in advance, to register
193 See, e.g., State v. Stark, 179 N.W.2d 597, 600 (Minn. 1970) (“The test is whether
the law-enforcement agency as a corporate body possessed sufficient information to
establish probable cause.”); State v. Dowdell, No. CA 9334, 1985 WL 4767, at *2 (Ohio
Ct. App. Dec. 20, 1985) (noting that police department “operates as a single unit”).
194 See, e.g.,
E
RNEST
R. A
LEXANDER
, H
OW
O
RGANIZATIONS
A
CT
T
OGETHER
77-22
(1995); M
ARY
D
OUGLAS
, H
OW
I
NSTITUTIONS
T
HINK
111–28 (1986);
G
ARETH
M
ORGAN
,
I
MAGES OF
O
RGANIZATION
73–214 (
2d ed.
1997);
Daniel M. Wegner, Transactive Mem-
ory: A Contemporary Analysis of the Group Mind, in
T
HEORIES OF
G
ROUP
B
EHAVIOR
185,
186–99 (Brian Mullen & George R. Goethals eds., 1987); Sasha A. Barab & Jonathan
A. Plucker, Smart People or Smart Contexts? Cognition, Ability, and Talent Development in an
Age of Situated Approaches to Knowledge and Learning, 37
E
DUC
. P
SYCHOLOGIST
165,
173–78 (2002); Daniel M. Wegner, A Computer Network Model of Human Transactive
Memory, 13
S
OC
. C
OGNITION
1 (1995); Karl E. Weick & Karlene H. Roberts, Collective
Mind in Organizations: Heedful Interrelating on Flight Decks, 38
A
DMIN
. S
CI
. Q.
357,
358–68 (1993). For another approach to this problem, concerned not with joint deci-
sionmaking but with how group decisions may not be reducible to the decisions of
individual members, see Philip Pettit, Groups with Minds of Their Own, in
S
OCIALIZING
M
ETAPHYSICS
167 (Frederick Schmitt ed., 2003); Philip Pettit, Responsibility Incorporated
(manuscript on file with the author).
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2007] constructive knowledge 1137
opposing views, and to provide a rationale for its action, it has already
sacrificed time and effort that might have been spent on other regula-
tions, and this decision reflects the agency’s judgment that such cau-
tion is warranted.
In the constructive-knowledge context, on the other hand, the
cost of deliberation is low, and eliminating this requirement does not
facilitate the information-gathering process; instead, it randomly vali-
dates probable-cause determinations in some instances. If probable
cause itself were a public good, that result might be defensible. But
probable cause is only an instrumental public good, a means towards
the goal of achieving convictions of guilty persons. Probable cause
requires only a solid basis for suspicion, for pressing further.
195
A rule
that simply facilitates the development of more probable cause, then,
is only marginally helpful at best if that result is riddled with the
problems of cognitive bias discussed earlier.
Ultimately, the constructive-knowledge rule serves none of the
goals achieved by other Fourth Amendment shortcuts. It does little to
help the police develop a quicker or more effective investigatory strat-
egy, it does not systematically minimize the procedural prerequisites
for establishing probable cause, and the procedural requirements it
eliminates do not even impose significant burdens on the police. At
the same time, to the extent that the rule dispenses with those
requirements, it imposes a potentially heavy cost on the accuracy of
probable-cause determinations.
IV. T
HE
P
ROBABLE
-
CAUSE CALCULUS
In questioning the premises of the constructive-knowledge rule,
this discussion has emphasized the role of foreseeability in Fourth
Amendment analysis, the use of criminal procedural shortcuts as tools
that the police can rely on when planning investigations, and the sig-
nificance of collaborative deliberation in administrative decisionmak-
ing. This Part briefly returns to the question of the fixed probable-
cause standard in light of these issues.
The conclusion of Part III might be paraphrased with the aid of
Mathews v. Eldridge.
196
Enumerating the factors to be considered
before the government may terminate a benefit, Mathews specified
195 See, e.g., Tracey Maclin, The Pringle Case’s New Notion of Probable Cause: An
Assault on Di Re and the Fourth Amendment, 2004
C
ATO
S
UP
. C
T
. R
EV
. 395, 435 (explain-
ing that under the analysis in Pringle v. Maryland, 540 U.S. 366 (2003), “probable
cause [is] sufficiently elastic to allow police to arrest and interrogate in order to
decide which persons to charge.”).
196 424 U.S. 319 (1976).
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1138 notre dame law review [vol. 82:3
that the court should take into account the government’s interest, the
private party’s interest, and “the risk of an erroneous deprivation
of . . . [the private party’s] interest through the procedures used.”
197
In the usual Fourth Amendment case, all three considerations are
already settled: the balance between policing and privacy is built into
the probable-cause standard, which also accepts that there is some
limited risk of erroneous deprivation (i.e., infringement of an inno-
cent suspect’s privacy interest) in any predictive claim about the out-
come of a search.
198
No Mathews-type analysis is necessary, because
the requisite degree of cause remains fixed regardless of the offense.
But the requirement that a home cannot be searched without a
warrant points to a change in the equation. Because of the home-
owner’s heightened privacy interest,
199
we require more formal
advance justification, with a magistrate’s review, to lower the risk of
erroneous deprivation. The alternative solution would be to allow for
warrantless searches of homes when the governmental interest is cor-
respondingly stronger, but the Supreme Court has rejected this bal-
ancing approach.
200
If probable cause is the product of a group decision, the risk of
erroneous deprivation rises when the court aggregates the facts ex
post and attributes to the acting officer a decision based on those
facts. In the constructive-knowledge cases—involving warrantless
searches—the courts have not acknowledged this heightened risk.
Again, the problem might be solved by applying the constructive-
knowledge rule only when the government has a heightened interest
(or when the suspect’s privacy interest is slight), but that would
require balancing. Allowing for constructive knowledge only during
Terry stops will not work, because there, too, the equilibrium between
invasiveness and privacy is already fixed, and would be disrupted by an
alteration that increases the risk of error.
Finally, there is no question of introducing a warrant require-
ment, as in the home searches. If a warrant were a practical possibil-
ity, imputation would be completely unnecessary. This analysis
suggests once again that unless the acting officer can predict the
result of his colleagues’ search—so that the risk of error diminishes—
the unshared knowledge should not be imputed.
197 Id. at 335.
198 See supra note 189.
R
199 See Georgia v. Randolph, 126 S. Ct. 1515, 1523–24 (2006); Kyllo v. United
States, 533 U.S. 27, 34–35 (2001); United States v. Karo, 468 U.S. 705, 714 (1984);
United States v. Knotts, 460 U.S. 276, 282 (1983).
200 See Dunaway v. New York, 442 U.S. 200, 213–16 (1979).
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2007] constructive knowledge 1139
This way of representing the probable-cause calculus also helps to
explain the imprecision of the probable-cause standard itself. Cast as
an equation with the help of Mathews, the probable-cause calculus has
very few moving parts and therefore offers little opportunity for
adjustment in a given case. The play in the joints, then, depends for
the most part on flexibility in accommodating the variety of justifica-
tions and kinds of knowledge that the police may rely on to show that
they have a persuasive basis for undertaking a search or arrest in the
first place. Indeed, without the Supreme Court’s repeated emphasis
on a “practical,” “commonsense,” “nontechnical” understanding of
probable cause, it is hardly likely that the idea of a fixed standard
could find support.
The breadth of probable cause also makes it a flexible tool from
an administrative point of view. Depending on the department’s pri-
orities, resources may be allocated according to different probable-
cause thresholds for different offenses. Thus even with an unvarying
standard, the department remains free to vary what it demands of its
officers, either to control the caseload by focusing attention on cer-
tain categories of offenses, or to control criminal conduct by striving
to develop particularly strong cases against certain types of offenders.
This way of allocating resources may have a dynamic effect on
probable-cause analysis as applied in court. The more resources the
police direct at certain kinds of crimes, the more expert the officers
become in the habits and strategies of the criminals who engage in
that conduct. And because “expertise” is a relevant consideration in
the court’s evaluation of probable cause, a department with more
experts in various areas of crime may in turn find it easier to develop
probable cause in each of those categories.
At the same time, because the flexibility occurs primarily in the
means of establishing probable cause, rather than in adapting the vari-
ous factors in the equation, Fourth Amendment doctrine is ridden
with on/off switches—exceptions, and exceptions to exceptions, relat-
ing to the warrant requirement, the exclusionary rule, and the need
for any cause at all.
201
Such all-or-nothing reasoning is prevalent
201 See, e.g., Akil Reed Amar, Fourth Amendment First Principles, 107
H
ARV
. L. R
EV
.
757, 802 (1994) (“Because the seriousness of a crime matters, the Court in Welsh v.
Wisconsin in effect proclaimed that there should be a ‘minor offense’ (Welsh) excep-
tion to the ‘exigent circumstances’ (Warden) exception to the ‘home arrest’ ( Payton)
exception to the usual ‘arrest’ (Watson) exception to the so-called ‘warrant require-
ment’ (Johnson).”); Anthony Amsterdam, Perspectives on the Fourth Amendment, 58
M
INN
.
L. R
EV
. 349, 374–75 (1974) (observing that the wild proliferation of exceptions to the
warrant requirement might be likened to the growth of different kinds of easements,
as described by an apocryphal writer whose treatise first described fourteen kinds,
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1140 notre dame law review [vol. 82:3
because aside from the factors constituting probable cause itself, war-
rants and exclusion are virtually the only options available as a means
of modifying the solution to a Fourth Amendment problem.
This crazy quilt of exceptions, in turn, has helped to promote a
view of Fourth Amendment law as a bureaucratic, rule-governed
enterprise. Indeed, numerous decisions reflect a mentality that treats
this body of law not as a set of norms but as a collection of technical
rules on a checklist, to be consulted and applied individually.
202
Freed from their normative moorings, the rules may begin to dis-
play a kind of doctrinal mutation.
203
That tendency may explain how
the collective-knowledge rule, originally crafted to treat an instruction
as a means of imputing information, could find itself applied even
when there has been no instruction at all.
One piece of support for that view comes from the cases insisting
that probable cause must be analyzed “not on the facts as an omnis-
cient observer would observe them, but on the facts as they would
have appeared to a reasonable person in the position of the arresting
officer—seeing what he saw, hearing what he heard.”
204
That observa-
tion typically appears not in suppression cases, but as a response to
§ 1983 plaintiffs.
205
In other words, the courts feel most compelled to
reject the idea of omniscience when there is a risk that imputing infor-
mation to the acting officer would make the officer liable for a civil
rights violation. Imputation under § 1983 would be inappropriate in
any case, but rather than framing their decision in those terms, the
then reported on thirty-nine kinds in the next edition, and finally concluded, in a
posthumous edition that “[i]t is impossible to say how many kinds of easements are
recognized by the law”).
202 For useful discussions of Fourth Amendment jurisprudence as bureaucratic,
see, for example, Amar, supra note 201, at 800. See generally Craig M. Bradley, Two
R
Models of the Fourth Amendment, 83
M
ICH
. L. R
EV
. 1468, 1482–83 (1985) (discussing
nine search and seizure cases from the 1982–83 term of the Supreme Court); Wayne
R. LaFave, Fourth Amendment Vagaries (of Improbable Cause, Imperceptible Plain View, Noto-
rious Privacy, and Balancing Askew), 74 J.
C
RIM
. L. & C
RIMINOLOGY
1171 (1983); Erik G.
Luna, Sovereignty and Suspicion, 48
D
UKE
L.J. 787, 787–88 (1999) (stating that each
new Fourth Amendment doctrine “is more duct tape on the Amendment’s frame and
a step closer to the junkyard”).
203 Such mutation is perhaps the converse of the memetic proliferation that J.M.
Balkin has discussed. See
J.M. B
ALKIN
, C
ULTURAL
S
OFTWARE
43 (1998) (discussing
Richard Dawkins’s coinage of “memes” in The Selfish Gene and explaining that “memes
are spread from person to person by observation and social learning”).
204 Mahoney v. Kesery, 976 F.2d 1054, 1057 (7th Cir. 1992).
205 See id.; see also, e.g., Miller v. Lewis, 381 F. Supp. 2d 773, 781 (N.D. Ill. 2005);
Flynn v. Mills, 361 F. Supp. 2d 866, 873 (S.D. Ind. 2005); Crowe v. County of San
Diego, 303 F. Supp. 2d 1050, 1071 (S.D. Cal. 2004).
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2007] constructive knowledge 1141
courts raising this issue have insisted that omniscience has no place in
the analysis of probable cause.
Yet the courts have not reconciled this principle from the § 1983
cases with their probable-cause jurisprudence, seemingly because of
their emphasis on a flexible probable-cause standard, coupled with a
rule-oriented mentality that focuses on individual doctrinal items
rather than considering the uniformity of probable-cause jurispru-
dence across contexts. The result is that even in suppression cases, a
court may recite this view of omniscience as part of the catalogue of
truisms about probable cause—and may then apply the constructive-
knowledge rule anyway.
206
C
ONCLUSION
Practically, the mutation of collective knowledge into constructive
knowledge has depended on a string of misinterpretations and unac-
knowledged expansions.
207
The courts’ failure to specify an “inevita-
ble discovery” restriction has created the opportunity for a relatively
surreptitious rule to proliferate unchecked. As noted earlier, the
requirement that the police officers must be working closely together
does not seem likely to restrain the rule’s application, and may itself
give way through the same process of expansion that has allowed the
constructive-knowledge rule to flourish.
There are good reasons for skepticism about the “inevitable dis-
covery” rationale in this context. When information is assembled after
the fact to support probable cause, the evidence probably will not
accurately reflect the universe of information available to the police at
the time of the challenged action. Thus it would make sense for
courts to refuse the invitation to rely on that evidence when evaluating
probable cause. The “inevitable discovery” rule is sufficiently well
entrenched, however, that courts are unlikely to close the door to the
notion of “inevitable communication.” At a minimum, making this
premise explicit would allow the courts to distinguish between the
cases where it applies and those where it has no purchase, and would
make it clear that imputation is appropriate only if the government
can meet a burden of proof at least as demanding as the one required
for “inevitable discovery.” Given that the constructive-knowledge rule
206 See, e.g., United States v. Parra, 402 F.3d 752, 764–65 (7th Cir. 2005) (quoting
Mahoney, 976 F.2d at 1057, and then explaining the procedure for aggregating
unshared information when “‘officers are in communication with each other while
working together at a scene.’” (quoting United States v. Nafzger, 974 F.2d 906, 911
(7th Cir. 1992))).
207 See supra notes 75–87, 144–47, and accompanying text.
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has passed under the radar so far, this first step could make a signifi-
cant difference in controlling the rule’s further development.
