Against Efforts to Simplify Antitrust

Abstract

Antitrust analysis is famously complex, fact intensive, and time consuming. But should we aspire for it to be otherwise? I offer two cautionary conjectures in opposition to the search for simpler rules. First, I conjecture that efforts to convert vague antitrust standards into clear rules will rarely succeed without abandoning the underlying standards that the rules were meant to simplify. Second, I conjecture that failed efforts at simplifying antitrust law will often have the opposite effect-increasing the apparent complexity and vagueness of this law. If these conjectures are correct, then the search for simpler rules could be not just unproductive but counterproductive in antitrust law.

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Against Efforts to Simplify Antitrust
Sean P. Sullivan*
Antitrust analysis is famously complex, fact intensive, and time consuming. But should
we aspire for it to be otherwise? I offer two cautionary conjectures in opposition to the
search for simpler rules. First, I conjecture that efforts to convert vague antitrust standards
into clear rules will rarely succeed without abandoning the underlying standards that the
rules were meant to simplify. Second, I conjecture that failed efforts at simplifying antitrust
will often have the opposite effect—increasing the apparent complexity and vagueness of
this law. If these conjectures are correct, then the search for simpler rules could be not just
unproductive but counterproductive in antitrust law.
I. INTRODUCTION ............................................................................................................. 419
II. CONJECTURE 1: EFFORTS TO SIMPLIFY RARELY SUCCEED ......................................... 421
A. Categories of Analysis ...................................................................................... 421
B. Structural Presumptions ................................................................................... 426
III. CONJECTURE 2: FAILURE TO SIMPLIFY COMPLICATES .............................................. 430
A. What Makes Antitrust Complicated? ................................................................ 431
B. Spiraling Complication .................................................................................... 434
IV. CONCLUSION ............................................................................................................. 436
I. INTRODUCTION
Frustration with the complexity and vagueness of antitrust law is as old as the law
itself.1 Older if we credit the common law struggles and legislative debates that catalyzed
passage of the major antitrust statutes.2 The sparse language of the Sherman, Clayton, and
* Professor of Law and Bouma Faculty Fellow in Law, University of Iowa College of Law. I am grateful
for comments from Christine Bartholomew, Joe Bial, Richard Epstein, Michal Gal, Erik Hovenkamp, Thom
Lambert, Robert Miller, and others at the Classical Liberal Institute and Journal of Corporation Law “New Age
of Antitrust” panel discussion. An earlier version of this work benefitted from discussion in the University of
Iowa Summer Workshop series. Maya Sanaba and Cassandra Ehly provided invaluable research assistance.
1. E.g., N. Sec. Co. v. United States, 193 U.S. 197, 406 (1904) (Holmes, J., dissenting) (“It would seem to
me impossible to say that the words ‘every contract in restraint of trade is a crime, punishable with imprisonment,’
would send the members of a partnership between, or a consolidation of, two trading corporations to prison . . . .
Yet those words would have that effect if this clause of § 1 applies to the defendants here . . . . According to
popular speech, every concern monopolizes whatever business it does, and if that business is trade between two
states it monopolizes a part of the trade among the states. Of course, the statute does not forbid that.”).
2. See William F. Dana, “Monopoly” Under the National Anti-Trust Act, 7 HARV. L. REV. 338, 355 (1894)
(“The Act is necessarily vague, because, in men’s minds, the evil dreaded is vague, and like words, therefore,
have been used to express it. The English judges seem to have been clearly conscious of the difficulties ahead
when, in Mogul Steamship Co. v. McGregor, . . . Fry, J., said: ‘I myself should deem it to be a misfortune if we
were to attempt to prescribe to the business world how honest and peaceable trade was to be carried on, in a case
where no such illegal elements as I have mentioned exist, or were to adopt some standard of judicial

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420 The Journal of Corporation Law [Vol. 49:2
FTC Acts concentrates the full weight of this body of law onto the points of a few
unenlightening words: “restraint of trade,”3 “monopolize,”4 “lessen competition,”5 “unfair
methods of competition.”6 Thomas Krattenmaker, Robert Lande, and Steven Salop have
said of the Sherman Act that “it is questionable whether a more ambiguous antitrust statute
could be devised.”7 Section 5’s prohibition on “unfair methods of competition” proves that
it could be.8
Some of the uncertainty surrounding these terms once owed to their use in pursuing
multiple, often conflicting, social and political objectives.9 Even when focused by the
consumer welfare standard,10 however, assessing whether challenged conduct
unreasonably restrains trade or lessens competition is usually a difficult, time consuming,
and fact-intensive task. For decades, the search for shortcuts—rules, presumptions,
structured frameworks for decision-making—has thus been a fixture of antitrust law.11
Frederick Schauer hypothesizes that, in situations including antitrust, the interactions
of decisionmakers and governed agents can drive convergence between rules and
standards.12 The unpredictability and discomfort of vague standards (think, unreasonable
restraint of trade) will motivate actors to seek out clearer rules to provide at least some
predictability and footholds in the litigation process (think, rules of per se illegality).13
Clear rules, in turn, will be chipped and shaded, over years of strategic behavior and the
reasonableness, or of normal prices, or fair freights, to which commercial adventurers, otherwise innocent, were
bound to conform.’” (quotation marks omitted)).
3. Sherman Act § 1, 15 U.S.C. § 1 (2022).
4. Sherman Act § 2, 15 U.S.C. § 2 (2022)
5. E.g., Clayton Act §7, 15 U.S.C. § 18 (2022).
6. Federal Trade Commission Act § 5, 15 U.S.C. § 45 (2022).
7. Thomas G. Krattenmaker, Robert H. Lande & Steven C. Salop, Monopoly Power and Market Power in
Antitrust Law, 76 GEO. L.J. 241, 243 (1987).
8. See Frederick Schauer, The Convergence of Rules and Standards, 2003 N.Z. L. REV. 303, 309
(commenting that even “the vague proscriptions of the Sherman Act are less vague than a simple prohibition on
‘unfair’ business dealings”); see also FTC v. Raladam Co., 283 U.S. 643, 648–50 (1931) (considering what the
words “unfair methods of competition” could mean and discussing some of the relevant legislative record).
9. Cf. Herbert Hovenkamp, Whatever Did Happen to the Antitrust Movement?, 94 NOTRE DAME L. REV.
583, 584–89 (2018) (discussing the various objectives that have been pursued during periods of populism);
JONATHAN B. BAKER, THE ANTITRUST PARADIGM: RESTORING A COMPETITIVE ECONOMY 57–61 (2019)
(commenting on the past experience of using antitrust law to pursue various social goals); Mathias Dewatripont,
Ian Jewitt & Jean Tirole, The Economics of Career Concerns, Part II: Application to Missions and Accountability
of Government Agencies, 66 REV. ECON. STUD. 199, 212 (1999) (modeling negative consequences of assigning
government agencies fuzzy, unfocused missions).
10. Ambiguities in the consumer welfare standard are not critical to the following discussion, though they
may accentuate concerns about vagueness. See, e.g., Steven C. Salop, Question: What Is the Real and Proper
Antitrust Welfare Standard? Answer: The True Consumer Welfare Standard, 22 LOY. CONSUMER L. REV. 336,
348–53 (2010) (discussing interpretations of this standard); C. Scott Hemphill, Less Restrictive Alternatives in
Antitrust Law, 116 COLUM. L. REV. 927, 927 (2016) (discussing how possible alternatives factor into analysis);
Rebecca Haw Allensworth, The Commensurability Myth in Antitrust, 69 VAND. L. REV. 1, 46 (2016) (critiquing
the notion of balancing harms and benefits).
11. See Herbert Hovenkamp, The Rule of Reason, 70 FLA. L. REV. 81, 121 (2018) (“Antitrust cases are
complex, and judges depend critically on presumptions and other evidentiary shortcuts.”); Frank H. Easterbrook,
The Limits of Antitrust, 63 TEX. L. REV. 1, 12 (1984) (“When everything is relevant, nothing is dispositive.”).
12. Schauer, supra note 8, at 311–12.
13. Id. at 315–19.

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selection of disputes for litigation, into vaguer standards (like enquiries meet for the
case).14
Schauer’s hypothesis seems accurate as applied to antitrust law. But I would append
two further conjectures in this context. First, efforts to convert vague antitrust standards
into clear rules will rarely succeed—at least, not without abandoning the underlying
standards that the rules are said to simplify. Second, failed attempts to simplify antitrust
law will exacerbate the apparent complexity and vagueness of this law—energizing further
efforts to simplify it, which will further obfuscate it, and so on.
If these conjectures are correct, then well-intentioned (but unsuccessful) efforts to
clarify antitrust law could be fueling the very discontent that this body of law now faces. It
could be better, at least from the perspective of a non-expert audience, for antitrust law to
present its difficulty honestly (to be clearly vague) than for antitrust law to hide its
difficulty behind appealing but ultimately unsuccessful shortcuts (to be vaguely clear).
II. CONJECTURE 1: EFFORTS TO SIMPLIFY RARELY SUCCEED
My first conjecture is that efforts to simplify vague antitrust standards rarely
succeed—at least, not without abandoning the underlying standards. Among the many
examples that could be used to illustrate this claim, two well-known cases are the categories
of analysis in section 1 litigation and the structural presumption in section 7.
A. Categories of Analysis
Start with section 1, and the struggle to simplify rule of reason analysis. As described
by Justice Brandeis in Chicago Board of Trade, the rule of reason inquiry (whether a
restraint suppresses and destroys competition or merely regulates and promotes it)15
involves an exhaustive factual review in which nearly anything could be relevant
evidence.16 The substance of rule of reason analysis is more focused today than it was in
1918, but the magnitude of the inquiry in “full-blown rule-of-reason analysis”17 is still
daunting. In summarizing this inquiry, Donald Turner once discussed the difficulty of
obtaining relevant facts, of interpreting the facts that can be obtained, and of balancing the
conflicting implications of the facts so interpreted:
[E]conomic analysis often indicates that assessment of the net effects of
particular conduct requires consideration of several market factors, including
short-run and long-run effects. This requirement seems to recommend complex
rather than simple rules, but it may be difficult and costly to obtain adequate facts
for deciding individual cases where the outcome depends on assessing various
14. Id. at 312–15.
15. Bd. of Trade of Chi. v. United States, 246 U.S. 231, 238 (1918).
16. Id. (“To determine that question the court must ordinarily consider the facts peculiar to the business to
which the restraint is applied; its condition before and after the restraint was imposed; the nature of the restraint
and its effect, actual or probable. The history of the restraint, the evil believed to exist, the reason for adopting
the particular remedy, the purpose or end sought to be attained, are all relevant facts.”).
17. Polygram Holding, Inc. v. FTC, 416 F.3d 29, 34 (D.C. Cir. 2005).

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market factors as well as on balancing anticompetitive and procompetitive
effects.18
The rule of reason’s nuanced and fact-specific inquiry exhibits the benefits of vague
standards but also the disadvantages. Turner, like others, observed that the rule of reason
“suffers from several problems—vagueness, unpredictability, high costs of litigation, and
difficulties in obtaining facts.”19 The rule of reason has likewise been faulted for offering
too little guidance to the business community about where the boundaries of permitted
conduct lie.20 To these disadvantages, we might add the possibility that, even when all the
facts and arguments are considered, the factfinder may remain stunned by the magnitude
of the question, unable to decide who to believe and what to predict—much less able to
defend those decisions in any detail.21
Per se rules of categorical unreasonableness are usually presented as a way of
addressing the disadvantages of rule of reason analysis. First, per se rules are said to
increase the predictability of analysis and litigation outcomes.22 Second, per se rules are
said to promote business certainty and administrative efficiency.23 Third, per se rules are
justified as an unusually humble concession that courts are simply unequipped to engage
in the kind of difficult economic balancing that the rule of reason demands. The Supreme
Court drew special attention to this final point in Topco:
The fact is that courts are of limited utility in examining difficult economic
problems. Our inability to weigh, in any meaningful sense, destruction of
competition in one sector of the economy against promotion of competition in
another sector is one important reason we have formulated per se rules.24
18. Donald F. Turner, The Durability, Relevance, and Future of American Antitrust Policy, 75 CALIF. L.
REV. 797, 799 (1987).
19. Id. at 800; see also Easterbrook, supra note 11, at 12–13 (“Litigation costs are the product of vague rules
combined with high stakes, and nowhere is that combination more deadly than in antitrust litigation under the
Rule of Reason.”).
20. Easterbrook, supra note 11, at 12 (“The [Chicago Board of Trade] formulation offers no help to
businesses planning their conduct.”).
21. See, e.g., N. Pac. Ry. Co. v. United States, 356 U.S. 1, 5 (1958) (decrying “incredibly complicated and
prolonged economic investigation into the entire history of the industry involved, as well as related industries” as
“an inquiry so often wholly fruitless when undertaken”); cf. Timothy J. Brennan, Is Complexity in Antitrust a
Virtue? The Accuracy-Simplicity Tradeoff, 59 ANTITRUST BULL. 827, 835–37 (2014) (observing that accuracy is
not always desirable if it comes at a cost relative to simpler decision rules).
22. See, e.g., id. (“This principle of per se unreasonableness . . . makes the type of restraints which are
proscribed by the Sherman Act more certain to the benefit of everyone concerned.”); United States v. Topco
Assocs., Inc., 405 U.S. 596, 609 n.10 (1972) (“Should Congress ultimately determine that predictability is
unimportant in this area of the law, it can, of course, make per se rules inapplicable in some or all cases, and leave
courts free to ramble through the wilds of economic theory in order to maintain a flexible approach.”).
23. Arizona v. Maricopa Cnty. Med. Soc’y, 457 U.S. 332, 344 (1982) (“For the sake of business certainty
and litigation efficiency, we have tolerated the invalidation of some agreements that a fullblown inquiry might
have proved to be reasonable.”); see also Topco, 405 U.S. at 609 n.10 (“Without the per se rules, businessmen
would be left with little to aid them in predicting in any particular case what courts will find to be legal and illegal
under the Sherman Act.”); FTC v. Superior Ct. Trial Laws. Ass’n, 493 U.S. 411, 430 (1990) (“The administrative
efficiency interests in antitrust regulation are unusually compelling.”).
24. Topco, 405 U.S. at 609–10; see also Hovenkamp, supra note 11, at 99 (“Antitrust cases in the United
States are decided by generalist judges, many of whom lack economics training. Further, facts are often

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All this hornbook antitrust law is consistent with Schauer’s hypothesis that courts and
litigants facing vague standards will seek to convert those standards into clear rules.25 But
are the per se rules clearer than the background standard? True, the rule that price fixing
is per se illegal obviates the need to decide whether price fixing is unreasonable under the
rule of reason.26 In place of this inquiry, though, it substitutes the need to decide what
counts as price fixing. And, here, efforts to craft vague standards into clear rules meet an
opposing force: the tendency of strategic behavior and selective litigation to blur clear rules
into vague standards.27
This is particularly so in the context of U.S. antitrust litigation where, even if the
federal antitrust agencies were to exercise untempted wisdom in challenging only the
clearest cases of price fixing, the litigation incentives of private plaintiffs would guarantee
eventual testing of the limits of what price fixing entailed.28 Pressed for a definition, courts
could then proceed in one of two ways. One way would be to adopt arbitrary definitions of
price fixing unrelated to the underlying standard. This would protect the predictability and
certainty of the per se rule but would uncouple it from the background rule of reason
standard.29 Conduct found to violate this type of per se rule might not often—or ever—be
found anticompetitive if assessed under the rule of reason. The category would be clear but
the justification for holding conduct illegal would not be.
The other possibility—and the one the Supreme Court has primarily pursued—is to
define the scope of the per se categories by reference to the underlying rule of reason
standard. Thus, in explaining why artists agreeing to set common pricing terms under the
blanket music licenses of ASCAP and BMI have not engaged in per se illegal price fixing,
the Court opined:
As generally used in the antitrust field, “price fixing” is a shorthand way of
describing certain categories of business behavior to which the per se rule has
been held applicable. The Court of Appeals’ literal approach does not alone
establish that this particular practice is one of those types or that it is “plainly
anticompetitive” and very likely without “redeeming virtue.” Literalness is
overly simplistic and often overbroad. When two partners set the price of their
determined by juries, who frequently lack any relevant training whatsoever. In such cases increased complexity
can produce poorer rather than better outcomes.”).
25. See supra note 14 and accompanying text (noting tendency of courts and litigants to try to craft clear
expressions of vague rules).
26. United States v. Socony-Vacuum Oil Co., 310 U.S. 150, 218 (1940) (“[P]rice-fixing agreements are
unlawful per se under the Sherman Act and that no showing of so-called competitive abuses or evils which those
agreements were designed to eliminate or alleviate may be interposed as a defense.”).
27. See supra note 13 and accompanying text (noting how litigation tends to covert initially clear rules into
less clear standards).
28. See Steven C. Salop & Lawrence J. White, Economic Analysis of Private Antitrust Litigation, 74 GEO.
L.J. 1001, 1049–52 (1986) (discussing the complicated incentives and policy implications of private antitrust
litigation); William J. Baumol & Janusz A. Ordover, Use of Antitrust to Subvert Competition, 28 J.L. & ECON.
247, 252–54 (1985) (similar, with particular attention to the influence of awards of treble damages).
29. But see Leegin Creative Leather Prods., Inc. v. PSKS, Inc., 551 U.S. 877, 894–95 (2007) (rejecting that
administrative convenience justifies per se rules except when the restraints in question are manifestly
anticompetitive); Cont’l T.V., Inc. v. GTE Sylvania Inc., 433 U.S. 36, 58–59 (1977) (“[D]eparture from the rule-
of-reason standard must be based upon demonstrable economic effect rather than . . . formalistic line drawing.”).

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goods or services they are literally “price fixing,” but they are not per se in
violation of the Sherman Act.30
As a term of art, price fixing thus becomes a label applied to conduct that would
usually be found to violate the rule of reason if it had been evaluated under that standard.
This reasoning extends to all per se categories. The Court made this clear in Leegin:
Resort to per se rules is confined to restraints . . . that would always or almost
always tend to restrict competition and decrease output. To justify a per se
prohibition a restraint must have manifestly anticompetitive effects and lack . . .
any redeeming virtue. As a consequence, the per se rule is appropriate only after
courts have had considerable experience with the type of restraint at issue, and
only if courts can predict with confidence that it would be invalidated in all or
almost all instances under the rule of reason.31
All this describes the per se categories of analysis, but the same pattern emerges in
the evolution of abbreviated analysis under section 1. To jump rapidly through the steps,
once “quick look” cases emerged as a possible third category of analysis,32 the question
immediately arose: what facts justified quick look treatment?33 Again, the answer could
have been that quick look cases would be identified by arbitrary definitions based on
precedent or administrative convenience. This would have preserved the rule-like character
of this category but would have uncoupled it from the background standard. In California
Dental Ass’n, the Supreme Court rejected that approach—indeed, rejected any sharp
delineation between quick-look and other categories of analysis—in favor of an approach
much like the one used in scoping the per se rules.34 Abbreviated inquiry, the Court said,
was only appropriate when a confident conclusion could be made about the effect of the
challenged restraint without the aid of considerations beyond the scope of the abbreviated
inquiry:
[T]here is generally no categorical line to be drawn between restraints that give
rise to an intuitively obvious inference of anticompetitive effect and those that
call for more detailed treatment. What is required, rather, is an enquiry meet for
the case, looking to the circumstances, details, and logic of a restraint. The object
is to see whether the experience of the market has been so clear, or necessarily
will be, that a confident conclusion about the principal tendency of a restriction
will follow from a quick (or at least quicker) look, in place of a more sedulous
one.35
30. Broad. Music, Inc. v. Columbia Broad. Sys., Inc., 441 U.S. 1, 9 (1979).
31. Leegin, 551 U.S. at 886–87 (internal quotation marks and citations omitted).
32. Nat’l Soc. of Pro. Eng’rs v. United States, 435 U.S. 679, 684 (1978); Nat’l Collegiate Athletic Ass’n v.
Bd. of Regents of Univ. of Okla., 468 U.S. 85, 89 (1984); FTC v. Ind. Fed’n of Dentists, 476 U.S. 447, 451
(1986).
33. See, e.g., James A. Keyte, What it Is and How it Is Being Applied: The “Quick Look Rule” of Reason,
11 ANTITRUST 21 (1997) (noting uncertainty about when quick look analysis should apply); Jay P. Yancey,
Comment, Is the Quick Look Too Quick?: Potential Problems with the Quick Look Analysis of Antitrust Litigation,
44 U. KAN. L. REV. 671 (1996) (similar).
34. Cal. Dental Ass’n v. FTC, 526 U.S. 756, 780–81 (1999).
35. Id.

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Put differently, abbreviated inquiry is permissible only when further inquiry would explore
issues of little value in evaluating the challenged restraint under the rule of reason.36
The result, today, is that the struggle to simplify rule of reason analysis in section 1
has produced a family of different modes of analysis. Per se illegality applies to conduct
that would always or almost always violate the rule of reason. Abbreviated inquiry may be
possible when less than full rule of reason study would permit confident predictions under
the rule of reason. All other conduct requires full rule of reason analysis. The question is
whether this framework simplifies anything.
Do the categories of analysis increase the predictability and decrease the
administrative costs of litigation? The clarity of result under a per se rule is beyond dispute.
And the omission of steps like market definition and market power inquiries in per se
analysis reduces litigation expenses when these rules apply. But, with per se categories
defined by reference to how a rule of reason inquiry would usually be resolved, the question
to ask is whether the per se label accomplishes anything that direct reliance on the
underlying standard would not. To be concrete, what does the per se rule do that an award
of judgment as a matter of law would not do under direct reliance on the rule of reason?
The same could be said of abbreviated modes of analysis. When the appropriate extent of
inquiry is defined by reference to how much inquiry the rule of reason would require, what
does this categorization accomplish that simple reliance on the underlying standard would
not?
Alternatively, perhaps the categories of analysis in section 1 help litigants to focus
their arguments and limit their discovery by enabling them to predict what evidence will
be required. This seems doubtful. For the reasons just discussed, direct reliance on the
substantive standard would appear to support the same predictions as the relevant
categories of analysis in most cases. And while something like per se treatment does limit
the pretrial information that the parties must consider, this limitation applies only where
per se treatment is guaranteed to apply. In cases where categorization is in any dispute, the
possibility of per se treatment may be of little value in limiting discovery or freeing parties
from preparing arguments.37
Finally, consider technical competency concerns. While categorical rules have been
promoted as a means of sidestepping vague rule of reason analysis,38 this argument falls
flat in a framework that bases categorization decisions on the likely outcome of evaluation
under the rule of reason. The failure is particularly stark in abbreviated analysis under the
California Dental standard. If the test of appropriate abbreviation is whether evaluation is
extensive enough to reach a “confident conclusion about the principal tendency of a
restriction,”39 then there is no plausible sense in which the availability of abbreviated
36. See FTC v. Actavis, Inc., 570 U.S. 136, 159–60 (2013) (“As in other areas of law, trial courts can
structure antitrust litigation so as to avoid, on the one hand, the use of antitrust theories too abbreviated to permit
proper analysis, and, on the other, consideration of every possible fact or theory irrespective of the minimal light
it may shed on the basic question—that of the presence of significant unjustified anticompetitive consequences.”).
37. See Hovenkamp, supra note 11, at 93 (“The problem with this sequence of events is that if there is any
reasonable chance that the court will ultimately require the rule of reason, the plaintiff has no choice but to proceed
through discovery under that rule even if the chance is small. This means that the value of the per se rule is lost
in a significant number of cases because the plaintiff must do all of the things that rule of reason analysis
requires.”).
38. United States v. Topco Assocs., Inc., 405 U.S. 596, 609 n.10 (1972).
39. Cal. Dental Ass’n, 526 U.S. at 781.

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inquiry saves courts from needing to master the rule of reason inquiry. Similar reasoning
applies to per se rules that are appropriate only when a court could “predict with confidence
that the restraint would be invalidated in all or almost all instances under the rule of
reason.”40
In short, categorical analysis may guide—but does not simplify—application of the
rule of reason in section 1 litigation. This is not to say that the categorical approach
produces bad outcomes; merely that the effort to streamline and simplify a vague antitrust
standard has failed. Categories of analysis are the illusion of certainty. The doubts and
complexities are still there, they are simply repackaged as questions of categorization.
B. Structural Presumptions
A single observation does not prove a pattern, so let’s consider a second instance in
which courts have sought to use a doctrinal shortcut to sidestep a vague and complicated
antitrust inquiry. In merger litigation under section 7 of the Clayton Act, the identification
of prohibited mergers (those with “probable anticompetitive effect”) generally requires an
extensive inquiry into the structure, history, and likely future of an industry,41 the ability
of new competitors to enter a market,42 the prospect that the merger would increase
competition or save an otherwise failing firm,43 and other considerations. In short, like the
rule of reason in section 1, the analysis of mergers under section 7 involves an exhaustive
factual and economic inquiry in which complexities abound and nearly anything could be
relevant evidence.44
Also like the rule of reason in section 1, the breadth and vagueness of this inquiry has
long energized efforts to increase the predictability and certainty of merger analysis by
adopting clearer rules.45 The importance of providing clarity to the business community is
40. Leegin Creative Leather Prods., Inc. v. PSKS, Inc., 551 U.S. 877, 886–87 (2007).
41. Brown Shoe Co. v. United States, 370 U.S. 294, 322 n.38 (1962) (“Statistics reflecting the shares of the
market controlled by the industry leaders and the parties to the merger are, of course, the primary index of market
power; but only a further examination of the particular market—its structure, history and probable future—can
provide the appropriate setting for judging the probable anticompetitive effect of the merger.”).
42. Id. at 322 (including in the relevant context of a merger whether the industry in which it was taking
place “had witnessed the ready entry of new competition or the erection of barriers to prospective entrants”).
43. Id. at 319 (“Congress recognized the stimulation to competition that might flow from particular mergers.
When concern as to the Act’s breadth was expressed, supporters of the amendments indicated that it would not
impede, for example, a merger between two small companies to enable the combination to compete more
effectively with larger corporations dominating the relevant market, nor a merger between a corporation which is
financially healthy and a failing one which no longer can be a vital competitive factor in the market.”).
44. See generally U.S. DEP’T OF JUST. & FED. TRADE COMM’N, HORIZONTAL MERGER GUIDELINES (2010)
[hereinafter 2010 HORIZONTAL MERGER GUIDELINES], https://www.ftc.gov/system/files/documents/
public_statements/804291/100819hmg.pdf [https://perma.cc/SUU4-66P3] (describing the principle analytical
approach of the federal antitrust agencies in merger review); FED. TRADE COMM’N, MODEL SECOND REQUEST
(2021), https://www.ftc.gov/system/files/attachments/hsr-resources/model_second_request_-_final_-_october_
2021.pdf [https://perma.cc/KPW2-5CUZ] (illustrating the scope of a typical Second Request).
45. E.g., Philip Elman, The Need for Certainty and Predictability in the Application of the Merger Law, 40
N.Y.U. L. REV. 613, 613 (1965) (“Because the stakes in merger policy are so high . . . it is essential to remove
the element of guesswork and gamble from merger planning . . . to make the application of the antitrust laws to
mergers more certain, more predictable, more incisive, and more prompt.”); see also George J. Stigler, Mergers
and Preventive Antitrust Policy, 104 U. PA. L. REV. 176, 182 (1955) (“It would be absurd to expect a thorough

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a long-running theme.46 The Supreme Court conceded this and other concerns about the
breadth of merger analysis in Philadelphia National Bank:
Clearly, . . . [whether the effect of a merger may be substantially to lessen
competition] is not the kind of question which is susceptible of a ready and
precise answer in most cases. It requires not merely an appraisal of the immediate
impact of the merger upon competition, but a prediction of its impact upon
competitive conditions in the future . . . . Such a prediction is sound only if it is
based upon a firm understanding of the structure of the relevant market; yet the
relevant economic data are both complex and elusive. And unless businessmen
can assess the legal consequences of a merger with some confidence, sound
business planning is retarded.47
For the Philadelphia National Bank majority, these deficiencies of the section 7
standard warranted adopting analytical shortcuts “in any case in which it is possible,
without doing violence to the congressional objective.”48 On this reasoning, the Court
announced the rule that has become the structural presumption in merger analysis:
[A] merger which produces a firm controlling an undue percentage share of the
relevant market, and results in a significant increase in the concentration of firms
in that market is so inherently likely to lessen competition substantially that it
must be enjoined in the absence of evidence clearly showing that the merger is
not likely to have such anticompetitive effects.49
In defending the consistency of this rule with the underlying standard, the Court
explained that the rule “lightens the burden of proving illegality only with respect to
mergers whose size makes them inherently suspect in light of Congress’ design in § 7 to
prevent undue concentration.”50 It also defended the rule as “fully consonant with
economic theory.”51
Today, the structural presumption’s pedigree is a topic of occasionally energetic
debate.52 Much could be said about the Court’s logic and to what extent it survived changes
investigation of each of the hundreds or thousands of mergers of interstate commerce dimensions that occur each
year. One must eliminate the vast majority of mergers from review . . . .”).
46. See Stigler, supra note 45, at 182 (“A set of rules . . . would serve the double purpose of giving the
business community some advance knowledge of public policy toward most mergers, and of achieving the
important goals of the legislation.”); see also Crown Zellerbach Corp. v. FTC, 296 F.2d 800, 827 (9th Cir. 1961)
(“[I]t is a bit hard to believe that Congress meant that a business concern contemplating merger must undergo a
. . . [complicated] struggle to find out whether its plans may or may not be carried out.”).
47. United States v. Phila. Nat’l Bank, 374 U.S. 321, 362 (1963) (citations omitted).
48. Id.
49. Id. at 363.
50. Id.
51. Id.; see also Frederick M. Rowe, The Decline of Antitrust and the Delusions of Models: The Faustian
Pact of Law and Economics, 72 GEO. L.J. 1511, 1524 (1984) (“[O]ligopoly-based legal norms promised clear
rules and quick results. Streamlining the tasks of lawyers and judges, presumptions predicted the prospects of
mergers from market shares and market structures, and obviated proof of anti-competitive purpose or effect.”).
52. See Sean P. Sullivan, What Structural Presumption?: Reuniting Evidence and Economics on the Role of
Market Concentration in Horizontal Merger Analysis, 42 J. CORP. L. 403, 405–06 (2016) (collecting critiques
and defenses of the wisdom and appropriate weight of the structural presumption).

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in economic theory and antitrust law’s embrace of the consumer welfare standard.53
Modern support for the structural presumption rests, however, not on the arguments of past
Supreme Court justices, but on the conviction that current incarnations of the structural
presumption continue to lighten the burden of proof54 in a way that streamlines evaluation
of merger challenges55 without doing violence to the underlying standard.56 That is, the
value of the structural presumption lies in how it simplifies merger analysis. But does it?
To start, the structural presumption cannot be invoked without market concentration
data, and market concentration data cannot be produced without first defining relevant
markets.57 There are usually several ways to draw market boundaries, so tests are needed
to select between the options. The Supreme Court has produced many such tests.58 Some
ask factfinders to struggle through questions of substitutability:59 what products are
reasonably interchangeable with other products, “price, use and qualities considered?”60
Since most goods and services are interchangeable with others at some prices, for some
uses, and in some cases—these tests usually end with a shrug.61 Other tests direct
factfinders to seek tangible evidence of market boundaries: what product characteristics
and practical indicia can be used to distinguish products into separate segments?62 This
approach turns out to be even less discriminating than the interchangeability approach and
also fails to produce markets or market shares with reliable relationships to the competitive
effects of mergers.63
Since the early 1980s, the Hypothetical Monopolist Test has provided a theoretically
sound way of defining relevant markets for assessing some anticompetitive effects of
53. See, e.g., Steven C. Salop, The Evolution and Vitality of Merger Presumptions: A Decision-Theoretic
Approach, 80 ANTITRUST L.J. 269, 276 (2015) (“This evolution to a weaker presumption based on market shares
and concentration is consistent with and was likely caused by the parallel evolution of economic analysis . . . .
Greater experience with merger investigations and enforcement also resulted in the antitrust agencies more
frequently concluding that transactions that increased concentration do not likely result in reduction in
competition.”); Herbert Hovenkamp & Carl Shapiro, Horizontal Mergers, Market Structure, and Burdens of
Proof, 127 YALE L.J. 1996, 2018–20 (2018) (contrasting modern merger analysis, in which market structure is
not a freestanding concern of antitrust law, with that of the 1960s, in which it was).
54. See Hovenkamp & Shapiro, supra note 53, at 2024 (“Merger analysis is almost always a predictive
exercise involving considerable uncertainty. As a result, burdens of proof matter a great deal. The structural
presumption . . . has therefore proven essential to effective merger enforcement.”).
55. See Salop, supra note 53, at 298 (predicting “substantial administrative efficiencies to courts from
formulating a presumption rather than just treating concentration and market shares as possibly relevant
evidence”).
56. Cf. Sullivan, supra note 52, at 426–27 (discussing the probative value of market concentration evidence
in merger review, independent of any “presumption” it supports).
57. See Sean P. Sullivan, Modular Market Definition, 55 U.C. DAVIS L. REV. 1091, 1122–24 (2021)
(identifying the ways that market definition connects measurements like market concentration to specific theories
of harm).
58. See id. at 1099 (“On what basis do we define markets? A glance at the market definition section of any
recent antitrust opinion will reveal several pages of potential tests.”).
59. See id. at 1099–1102.
60. United States v. E. I. du Pont de Nemours & Co. (Cellophane), 351 U.S. 377, 404 (1956).
61. Cf. David Glasner & Sean P. Sullivan, The Logic of Market Definition, 83 ANTITRUST L.J. 293, 305–07
(2020) (describing this and related deficiencies of substitutability-based tests).
62. See Sullivan, supra note 57, at 1102–06.
63. Id. at 1108–09.

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mergers.64 In brief, the HMT starts with a narrow candidate market drawn around products
of the merging firms and close substitutes. The test then asks whether a hypothetical
monopolist that controlled all products in the candidate market would find it profitable to
impose at least a small price increase on some of those products. If so, the HMT validates
that candidate market as a relevant market. If not, the candidate market is expanded to
include other substitute products, and the process starts over, iterating until a relevant
market is found.65
Relevant markets defined by the HMT can be helpful in merger review, but the
amount of evidence and analysis needed to define markets under this test cuts deep into the
promised simplicity of the structural presumption. The economic data needed to
operationalize the HMT is complex and elusive.66 Indeed, by the time that sufficient
information has been gathered to assess relevant markets under the HMT, the record will
already embrace much of the complicated analysis that the structural presumption was
meant to avoid.67 From this uninspiring start, the complexities of the structural presumption
continue to mount.
Next, the structure of competition must be assessed within each relevant market. This,
too, presents a series of questions. Who are industry participants, and should they be
defined to include firms that could quickly enter the relevant market?68 Is concentration
best reflected by the number of significant firms in the relevant market or by the market
shares of those firms?69 If shares are used, should they be measured in units sold or dollars
earned?70 Units produced or capacity available?71 The Supreme Court has instructed that
market structure should be measured in a way that presents a “proper picture of a
company’s future ability to compete.”72 Fair enough. But this wafts of running analysis in
circles: only after undertaking detailed industry analysis will it be possible to assess the
competitive significance of each competitor, so that market structure can be measured, so
64. See id. at 1111–15 (noting the poor fit of relevant markets defined by the HMT to theories of harm
surrounding the unilateral effects of mergers in differentiated-product markets).
65. See U.S. DEP’T OF JUST., MERGER GUIDELINES § II.A (1982) [hereinafter 1982 MERGER GUIDELINES],
https://www.justice.gov/sites/default/files/atr/legacy/2007/07/11/11248.pdf [https://perma.cc/9W5Y-ECPA]
(providing the first appearance of the HMT in agency guidelines); 2010 HORIZONTAL MERGER GUIDELINES,
supra note 44, § 4.1 (providing the current expression of the test). Looser expressions of the HMT are possible
and often better. See, e.g., LAWRENCE ANTHONY SULLIVAN, HANDBOOK OF THE LAW OF ANTITRUST 41 (1977).
66. Cf. United States v. Phila. Nat’l Bank, 374 U.S. 321, 362 (1963) (“Such a prediction is sound only if it
is based upon a firm understanding of the structure of the relevant market; yet the relevant economic data are both
complex and elusive.”).
67. See generally Louis Kaplow, Why (Ever) Define Markets?, 124 HARV. L. REV. 437, 466 (2010)
(interrogating whether market definition adds anything to direct assessment of competitive effects once the
relevant information has been gathered); Louis Kaplow, Market Definition Alchemy, 57 ANTITRUST BULL. 915
(2012) (similar); Louis Kaplow, Market Definition: Impossible and Counterproductive, 79 ANTITRUST L.J. 361
(2013) (similar).
68. See 2010 HORIZONTAL MERGER GUIDELINES, supra note 44, § 5.1 (discussing “participants” and “rapid
entrants”).
69. Cf. id. § 5.3 para. 4 (discussing reliance on the number of significant competitors).
70. See id. § 5.2 (discussing share computations).
71. Id.
72. United States v. Gen. Dynamics Corp., 415 U.S. 486, 501 (1974); see also id. at 503, 510 (similarly
focusing on future ability to compete).

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that the structural presumption can be invoked, so that this shortcut can be relied upon in
place of undertaking detailed industry analysis.
This is to say nothing of the rebuttal stage of the structural presumption. What
evidence can be used to rebut the presumption?73 How much evidence is required?74 What
effect does rebuttal have upon the plaintiff’s case?75 These questions are less settled than
one might expect;76 certainly, less settled than one would expect of a shortcut intended to
circumvent complicated legal inquiries.
Of course, all these complexities could be avoided through the adoption of arbitrary
rules. Market definition would be trivial if markets were simply defined by lookup against
North American Industry Classification System (NAICS) codes. Market structure would
present fewer challenges if it did not need to satisfy the General Dynamics requirement of
reflecting future competitive significance.77 The presumption of harm could be treated as
compulsory, eliminating rebuttal issues. These changes would, however, divorce the
structural presumption from the substantive standard of the effects-based section 7
inquiry.78 It is the effort to do justice to the background standard that introduces the
complexity.
By now, the pattern is clear enough that we can dispense with a rehashing of points
made in the discussion of categories of analysis in section 1. When properly used and
understood, the structural presumption is a useful tool in merger analysis. What it is not is
a shortcut to complicated merger analysis. The structural presumption is not simple. Each
step in the process gives way to labyrinthine sub-questions, answerable only by
complicated and fact-intensive analysis if the final result is to stay true to the underlying
standard. Another effort to simplify vague antitrust standards ends up as little more than
repackaged complexity.
III. CONJECTURE 2: FAILURE TO SIMPLIFY COMPLICATES
As I said before, the previous examples are representative illustrations. Similar
unpacking of superficially clarifying labels and heuristics could be performed for the
73. See United States v. Baker Hughes Inc., 908 F.2d 981, 984 (D.C. Cir. 1990) (asserting that “evidence
on a variety of factors can rebut a prima facie case” and counting “absence of significant entry barriers,” “the
misleading nature of the [market share] statistics,” and customer sophistication among the list of factors). But cf.
Sullivan, supra note 52, at 413–15 (discussing the different consequences of different modes of rebuttal).
74. It is often said that defendants must produce weightier evidence to rebut a stronger presumption. See,
e.g., Baker Hughes, 908 F.2d at 991 (“The more compelling the prima facie case, the more evidence the defendant
must present to rebut it successfully.”). Complexities arise, however, when presumptions are treated as having
evidentiary weight. See Ronald J. Allen, Presumptions in Civil Actions Reconsidered, 66 IOWA L. REV. 843, 855–
59 (1981). Unsurprisingly, this aspect of the burden-shifting framework has caused confusion. E.g., FTC v. CCC
Holdings Inc., 605 F. Supp. 2d 26, 46 (D.D.C. 2009) (“The courts have not established a clear standard that the
merging parties must meet in order to rebut a prima facie case . . . .”).
75. See Sullivan, supra note 52, at 428–31 (describing the proper effects of different forms of rebuttal).
76. See id. at 425–34 (identifying questions about the substantive and procedural implications of the
structural presumption and rebuttal evidence).
77. See supra note 72.
78. Cf. United States v. Phila. Nat’l Bank, 374 U.S. 321, 362 (1963) (recommending adoption of shortcuts
where doing so would be possible “without doing violence to the congressional objective”).

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distinction between naked and ancillary restraints,79 the identification of exclusionary
conduct under section 2 of the Sherman Act,80 the use of market shares to identify
monopoly power,81 the use of terms like “business justification” or “competition on the
merits” throughout antitrust law,82 the use of modified per se rules (and other labels) in
tying cases,83 and in other areas. Efforts to skip or simplify complex economic inquiries
rarely find lasting success.
My second conjecture is that failed attempts to simplify antitrust law will often
exacerbate the perceived complication and vagueness of this law. If so, and if this motivates
policymakers to attempt further simplifications, then failed efforts to simplify antitrust law
could spark entropic engines of self-fueling confusion and obfuscation.
A. What Makes Antitrust Complicated?
In Living with Complexity, Donald Norman differentiates (in a way that I have not)
between systems that are complex and systems that are complicated.84 Norman uses the
label of complexity to refer to features of the world.85 Personal computers must handle
millions of instructions per second to perform the tasks we expect them to perform. Making
that happen requires complex engineering, fabrication, and programming. This complexity
is unobjectionable. In fact, it is inescapable if we want computers to play the roles they do
in our daily lives.
The translation to antitrust is straightforward. The subject of antitrust law is nothing
smaller than modern, global commerce: a vast and intricate web of contracts, production
technologies, supply chains, distribution and marketing operations, consumption
schedules, and investment strategies. Making antitrust useful in regulating commerce
requires complex law and complex economics. And much as personal computers are
irreducibly complex, there may be few ways to reduce the complexity of antitrust law
without impairing its functionality. This reflects not just the intricacy and diversity of the
conduct to which antitrust applies, but also the disquieting reality that those whose conduct
79. Cf. Thomas B. Nachbar, Less Restrictive Alternatives and the Ancillary Restraints Doctrine, 45 SEATTLE
U. L. REV. 587 (2022) (critically unpacking difficulties in both less restrictive alternatives analysis and ancillary
restraints doctrine).
80. See PHILLIP E. AREEDA & HERBERT HOVENKAMP, ANTITRUST LAW ¶ 650a, at 92 (4th ed. 2015)
(describing the “exclusionary conduct” element of a section 2 monopolization offense as a term of art that
encompasses conduct impairing the opportunities of rivals and is not “competition on the merits,” while conceding
that “the term ‘exclusionary’ does not accurately capture all kinds of forbidden conduct” and observing that
“[s]ome practices, such as mergers, are monopolistic because they are inherently ‘collusive’ rather than
exclusionary”).
81. See sources cited supra note 67.
82. Cf. United States v. Microsoft Corp., 253 F.3d 34, 59 (D.C. Cir. 2001) (defining a “procompetitive
justification,” elsewhere referred to as a “legitimate justification,” as “a nonpretextual claim that [challenged
conduct is] a form of competition on the merits because it involves, for example, greater efficiency or enhanced
consumer appeal”); A. Douglas Melamed, Antitrust Law Is Not That Complicated, 130 HARV. L. REV. F. 163,
166 (2017) (defining “competition on the merits” as “conduct that on balance increases output”).
83. Cf. Hovenkamp, supra note 11, at 99 (“[T]he poorly conceived per se rules that the Supreme Court
adopted for tying arrangements during the 1950s and 1960s . . . produced very high error costs, certainly far higher
than any savings in administrative costs gained by use of a per se rule.”).
84. DONALD A. NORMAN, LIVING WITH COMPLEXITY 2 (2016).
85. Id. at 4 (“Complexity is part of the world . . . complexity by itself is neither good nor bad.”).

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is governed by antitrust law are acutely aware of its scope and limitations.86 Rules that are
easy to state and apply are often easy to evade and twist to unintended ends.
All this is to say that antitrust law is complex and probably must be so. Norman
distinguishes this type of natural and desirable complexity from objectionable
complication.87 The difference is subtle but important. Where complexity describes the
objective intricacy of a system, complication describes the subjective experience and
mental state of an observer.88 We perceive things as complicated when we lack appropriate
conceptual models for how they operate.89 Put another way, complication is how we
perceive the experience of not personally understanding how something works.90
Norman’s thesis is that perceptions of complication and simplicity are the result of
design choices.91 Good design makes complex systems feel simple. Modern cars are an
example. Cars are mechanically very complex, yet easy to operate with little training.
Conversely, poor design makes simple systems feel complicated. Anyone old enough to
have once struggled with a programmable VCR has first-hand experience with a system
that was not that complex, yet still managed to be maddeningly complicated.
In the context of consumer electronics, Norman comments that complexity increases
“when the design makes it difficult to know what is happening or when controls have
multiple meanings depending on context.”92 This is a dark omen for antitrust law, stuffed
as it is with terms of art and doctrines crusted with layers of reinterpretation and changed
meaning.
Is antitrust law complicated? Consider how the categories of analysis in section 1
appear to a non-expert user. The first step is deciding what standard of analysis will be
employed to judge the legality of the challenged conduct. Some conduct, like price fixing,
is per se illegal. But price fixing is a term of art, and some things that look like price fixing
are not per se illegal. Generally, the only way to know what conduct deserves per se
treatment is to be able to say that it would always—or almost always—be found to violate
the rule of reason. Some conduct gets evaluated under the rule of reason from the outset.
Other conduct is evaluated under a flexible standard: roughly, evaluation extensive enough
to reach a point where confident evaluation would be possible under the rule of reason.
To the antitrust expert, the previous paragraph is dry and unremarkable. To the
outsider, it is surreal. Things that seem like they should be clear and tangible, like “price
fixing,” turn out to be terms of art given life by the ominous (and apparently immense) rule
of reason standard. Abbreviated modes of inquiry are presented as a way of avoiding rule
of reason analysis, but one cannot predict whether an abbreviated inquiry is permissible
without predicting how a given type of challenge would fare under the rule of reason. The
86. See BAKER, supra note 9, at 21 (“[B]usinesses are taught to exploit gaps in antitrust rules to deter entry
and engage in coordinated conduct without running afoul of those rules.”).
87. NORMAN, supra note 84, at 45 (“Whether something is complicated is in the mind of the beholder.”).
88. Id.
89. See id. at 34 (“A conceptual model is the underlying belief structure held by a person about how
something works.”); id. at 40 (“What makes something simple or complex? It’s not the number of dials or controls
or how many features it has: It is whether the person using the device has a good conceptual model of how it
operates.”).
90. See id. at 47 (“Simplicity is a mental state, highly coupled with understanding. Something is perceived
as simple when its actions, options, and appearance match the person’s conceptual model.”).
91. Id. at 47–48.
92. Id. at 48.

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rule of reason ultimately dictates all outcomes in this framework, yet the user’s attention is
constantly diverted away from the rule of reason to focus on this categorization question
or that one. In short, the framework appears complicated because it does not suggest
appropriate conceptual models of what is happening and what drives outcomes.
Now consider the structural presumption in section 7. Merger challenges are permitted
to circumvent complex competitive-effects analysis when the concentration of a relevant
market is great enough to establish a presumption of illegality. Relevant markets are
defined by a variety of tests, with the leading test defining markets by reference to the
predicted competitive effects of a hypothetical combination of all competitors in a
candidate market.93 Market structure is likewise defined by reference to predicted
competitive effects—here, shares are assigned to make each competitor’s market share
reflect its future competitive significance relative to other competitors. The presumption of
illegality can be rebutted, but counterproof requires a weightier showing when the
presumption of illegality is particularly strong.
Again, this summary is hornbook law—and, again, it is bristling with opportunities
for confusion. As a term of art, no relevant market has any reliable claim of correspondence
to market or industry boundaries as they would be recognized by the public.94 A person
accustomed to hearing news about trends in the manufacturing sector or in Silicon Valley
may struggle to suspend disbelief that a relevant market could be as thin as “premium
natural and organic supermarkets”95 or “high function FMS and HRM [software].”96 The
suggestion that detailed industry study would be needed to measure market shares likewise
collides with a layperson’s expectations. The accounting exercise of adding and dividing
by the total seems unambiguous to a user not already looking at the exercise through the
lens of competitive-effects predictions. And the entire focus of the structural
presumption—on market concentration as an evidentiary proxy for the competitive effects
of mergers—is a head fake sure to be missed by many who reasonably assume that all the
talk about market concentration reveals an aspiration to stamp out concentration itself.97
To the outsider, the disconnect between how the components of the structural presumption
seem like they would work—and how they actually work—may feel like sitting down,
once more, in front of the cursed VCR.
93. The use of a hypothetical “monopolist” decisionmaker in the HMT is purely a matter of narrative
convenience. Alternative articulations could focus on a perfectly orchestrated cartel of all market participants, a
trust embracing all market participants, or a zero-integration merger of all market participants.
94. See 2010 HORIZONTAL MERGER GUIDELINES, supra note 44, § 4 para. 9 (“Relevant antitrust markets
defined according to the hypothetical monopolist test are not always intuitive and may not align with how industry
members use the term ‘market.’”).
95. FTC v. Whole Foods Mkt., Inc., 548 F.3d 1028, 1035 (D.C. Cir. 2008).
96. United States v. Oracle Corp., 331 F. Supp. 2d 1098, 1130 (N.D. Cal. 2004).
97. Compare Hovenkamp & Shapiro, supra note 53, at 2018 (“[M]arket structure has never been a
freestanding target of merger policy. Rather, market structure has been a means of tackling merger law’s more
fundamental concerns, which are higher prices or reduced output or other consumer harms that result from less
competitive market structures.”), with Exec. Order No. 14036, 86 Fed. Reg. 36987 § 1 (July 9, 2021) (affirming
“that it is the policy of my Administration to enforce the antitrust laws to combat the excessive concentration of
industry”).

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B. Spiraling Complication
Having discussed how efforts to simplify antitrust law often fail to do so, and how
failed efforts to simplify antitrust law complicate it by hiding the operation of this law
behind false conceptual models, the remaining step in building out my second conjecture
is to defend the concern that the antitrust law’s perceived complication could drive efforts
to simplify it, pulling the law into a downward spiral of obfuscation. Examples of the
hypothesized concern can be found in the statements and actions of policymakers and those
who influence them.
What are some examples? One—just discussed—is the possibility that confusion
about the significance of market structure will motivate efforts to harness its apparent
simplicity in increasing the speed and efficiency of antitrust analysis. By executive order,
President Biden recently announced his administration’s commitment to using antitrust law
to combat “the excessive concentration of industry.”98 In public remarks, agency leaders
have simplistically conflated rising concentration with falling competition and public
harm.99 In recent actions, the agencies have signaled an interest in reviving Warren-Court
style vigilance against perceived trends toward concentration.100 And recently proposed
legislation seeks to make mergers and other forms of conduct presumptively illegal when
undertaken by firms holding more than a 50% share of a relevant market.101 The goal of
simplifying and streamlining enforcement is transparent.102
These statements and policy proposals reflect an overreading of structural shortcuts
in antitrust analysis. They are based on conceptual models in which market structure relates
in simple and consistent ways to market power opportunities. The inaccuracy of these
conceptual models is not exposed by current law. To the contrary, the (inaccurate) models
98. Exec. Order No. 14036, 86 Fed. Reg. 36987 § 1 (July 9, 2021).
99. See JONATHAN KANTER, MODERN COMPETITION CHALLENGES REQUIRE MODERN MERGER
GUIDELINES 2 (2022), https://www.justice.gov/d9/speeches/attachments/2022/01/18/opening_remarks_-_joint_
press_conference_with_ftc_-_aag_kanter_0.pdf [https://perma.cc/J4MC-ZQV] (“[C]oncentrated market
structures can harm downstream consumers and upstream workers at the same time that they foster coordination
or exclusion in adjacent markets.”); Oversight of the Enforcement of the Antitrust Laws: Hearing Before the
Subcomm. on Antitrust, Competition Pol’y and Consumer Rts. of the S. Comm. on the Judiciary, 117th Cong.
(Sept. 20, 2022) (statement of Lina Khan, Chair, Federal Trade Commission), https://www.ftc.gov/system/files/
ftc_gov/pdf/P210100SenateAntitrustTestimony09202022.pdf [https://perma.cc/LH9Y-YDFR] (“Recent decades
have vividly illustrated how Americans lose out when markets become more consolidated and less competitive.”).
100. U.S. DEP’T OF JUST. & FED. TRADE COMM’N, REQUEST FOR INFORMATION ON MERGER ENFORCEMENT
2 (2022), https://www.justice.gov/opa/press-release/file/1463566/download [https://perma.cc/HVH9-XQ8Y]
(“The agencies are particularly interested in aspects of competition the guidelines may underemphasize or neglect,
such as . . . non-price elements of competition like innovation, quality, potential competition, or any ‘trend toward
concentration.’”); U.S. DEP’T OF JUST. & FED. TRADE COMM’N, DRAFT MERGER GUIDELINES 4 (2023),
https://www.justice.gov/d9/2023-07/2023-draft-merger-guidelines_0.pdf [https://perma.cc/F23Z-4VHK]
(“Guideline 8: Mergers Should Not Further a Trend Toward Concentration. If a merger occurs during a trend
toward concentration, the Agencies examine whether further consolidation may substantially lessen competition
or tend to create a monopoly.” (footnotes omitted)). But cf. Robert Pitofsky, The Political Content of Antitrust,
127 PA. L. REV. 1051, 1071 (1979) (commenting that even those who reject limiting antitrust to economic
concerns should find some of the Warren Court’s observations of a trend toward concentration in cases like Von’s
Grocery a dubious basis for intervention).
101. S. 225, 117th Cong. §§ 4, 9 (2021).
102. Id. § 2(b)(4) (explaining one purpose of the act as being to “establish simple, cost-effective decision
rules”).

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appear to match simple rules like the structural presumption in section 7 litigation.103 The
complexity of that presumption is not honestly exposed but hidden in behind-the-scenes
tweaks and careful definitions.104
Another example of recent interest in simplifying the perceived complication of
antitrust law can be found in efforts to identify categorical offenses for which detailed
factual analysis can be skipped or prohibited,105 the apparent objective being to mimic
some of the perceived simplicity of per se rules and abbreviated analysis.106 For example,
reasoning that the process of proving harm from platform integration is too difficult and
time consuming,107 Lina Khan has proposed blanket rules to prohibit platforms from
competing with their users.108 A reformulation of this rule would be to call all such vertical
integration per se anticompetitive. Apparently launching from a similar conviction that
current antitrust enforcement is failing to prevent unfair conduct by digital platforms,109
recently proposed legislation would make it unlawful for companies designated as
“covered platforms” to engage in specific categories of conduct.110 In some of the
prohibited categories of conduct, illegality depends on proof that the conduct would
“materially harm competition.”111 In other categories, the conduct is proscribed without
any showing of harm,112 though the defendant is permitted to prove absence of harm as an
affirmative defense.113 The latter style of prohibition codifies presumptive illegality within
a specified category of conduct.
The inspiration for these policy proposals is a little unclear. If the proposals are based
on beliefs that antitrust law’s existing per se rules and presumptions greatly simplify
103. See supra note 49 and accompanying text.
104. See supra notes 58–78 and accompanying text.
105. See Thomas A. Lambert & Tate Cooper, Neo-Brandeisianism’s Democracy Paradox, 49 J. CORP. L. 347
(2024) (discussing recent interest in bright-line conduct rules of illegality).
106. See, e.g., Zephyr Teachout, Why Judges Let Monopolists off the Hook, THE ATLANTIC (Oct. 29, 2021),
https://www.theatlantic.com/ideas/archive/2021/10/antitrust-facebook-congress-sherman-act/620539/
[https://perma.cc/8BSY-5XD9] (“Instead of asking judges to apply impossible standards, the law should spell out
and prohibit a specific set of abusive business practices . . . dominant firms should be explicitly banned from
predatory pricing, coercive dealing, and exclusive dealing, for example.”).
107. Lina M. Khan, The Separation of Platforms and Commerce, 119 COLUM. L. REV. 973, 1084 (2019)
(“Antitrust remedies would be costlier and take significantly longer, requiring the government or a private party
to successfully show anticompetitive conduct and effects stemming from a digital platform’s involvement in
multiple markets. Given the enfeebling of antitrust doctrines that police single-firm anticompetitive conduct—
and the judicial requirement that remedies be carefully tailored to competitive harm—this path is likely to be
significantly more challenging.”).
108. See id. at 1083–85 (discussing implementation options).
109. See Press Release, U.S. Senator Amy Klobuchar, Klobuchar, Grassley, Colleagues to Introduce
Bipartisan Legislation to Rein in Big Tech (Oct. 14, 2021), https://www.klobuchar.senate.gov/public/index.cfm/
2021/10/klobuchar-grassley-colleagues-to-introduce-bipartisan-legislation-to-rein-in-big-tech [https://perma.cc/
K7C6-RN9B] (quoting Senator Grassley for the proposition that “[a]s Big Tech has grown and evolved over the
years, our laws have not changed to keep up and ensure these companies are competing fairly”).
110. S. 2992, 117th Cong. § 2(a) (2022).
111. Id. § 2(a)(1).
112. E.g., id. § 2(b)(5) (proposing that conduct that “materially restrict[s] or impede[s] covered platform users
from un-installing software applications that have been preinstalled on the covered platform of changing default
settings that direct or steer covered platform users to products or services offered by the covered platform
operator” would constitute unlawful conduct).
113. Id. § 2(d)(2) (describing the referenced affirmative defense).

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436 The Journal of Corporation Law [Vol. 49:2
analysis, then they are misled. Efforts to remain faithful to the underlying standard tend to
evaporate promises of simplicity, as previously discussed.114 If, on the other hand, the
proposals are intended as rejections of antitrust law’s existing standards in favor of new
and different theories of harm, then perceptions of antitrust law’s overcomplication are
likely still a driving force—but with the important difference that the risk of spiraling
complication within antitrust law must be upgraded to spiraling complication without it.
IV. CONCLUSION
In moments like the present, when accepted principles of antitrust law are under
attack, it may feel tempting to accede to demands for clearer, more impactful enforcement
in the form of shortcuts to complex inquiries: rules, presumptions, and burden-shifting
frameworks. These modest concessions promise simplicity without abandoning the
substantive premises of antitrust law. But can this promise be kept?
I worry it cannot. As I have tried to illustrate, efforts to convert vague standards into
clear rules have an uninspiring track record in antitrust law. Worse than failing to simplify,
past efforts in this direction seem likely to have made antitrust harder to understand than it
would be with its vague standards and complex inquiries clearly in view. The troubling
implication is that the addition of new shortcuts to complex inquiries may simply set the
stage for deeper despair. In the long run, it could be better for antitrust law to be clearly
vague than for it to be vaguely clear.
114. See supra notes 26–36 and accompanying text.