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Broken Windows, Hot Spots, and Focused Deterrence:
The State of the “Big Three” Policing Strategies and Knowledge of Their Effects
Cory P. Haberman & Nathan W. Link
Pre-print subject to change. Please do not quote.
Forthcoming in Criminal Justice Theory, Volume 26 Explanations and Effects. Edited By Cecilia
Chouhy, Joshua C. Cochran, Cheryl Lero Jonson
Unfortunately, a “black box” defines much of what occurs as part of criminal justice
interventions (Goldkamp, White, & Robinson, 2001; Sampson, Winship, & Knight, 2013). This
fact is somewhat jarring given that theories are often explicitly or implicitly used to justify
government crime reduction and control initiatives. Many law enforcement strategies, for example,
are based on a clear set of theoretical guidelines, but the soundness of those arguments and the
efficacy of their implementation are too rarely subjected to empirical testing.
The importance of these law enforcement operations is paramount—they are critical in
protecting the public, they must be performed in a fair and constitutional fashion, and they require
extensive funding. In a time when financial coffers are limited and criminal justice operations are
under scrutiny, the need for assessing interventions’ theoretical and empirical foundations cannot
be overstated. Interventions based on defensible theory are more likely to “work”—usually defined
by improving public safety—and result in programs and policies that are reproducible across
In this context, the present chapter addresses three major law enforcement strategies—
broken windows-based policing, hot spots policing, and focused deterrence. Though other
strategies exist, we hone in on these in particular as they are currently or have been dominant
paradigms and therefore have large footprints on American justice. For each strategy, we
systematically define key constructs, discuss theoretical underpinnings and historical
development, review impact evaluations, and discuss some remaining gaps, untested mechanisms,
and unintended/collateral consequences. We conclude by discussing some overall gaps in criminal
justice theorizing and research within the context of the reviewed strategies and provide some
avenues for future theorizing and research.
Broken Windows Policing
Policing tactics stemming from broken windows theory have been labeled broken
windows, order maintenance, zero tolerance, and disorder-reduction programs. The unifying
theme is that social and physical disorders (e.g., loiterers, panhandlers, graffiti, and unkempt
properties) receive great law enforcement attention. Rooted theoretically in the “incivilities thesis”
(Taylor, 2001), addressing these problems is hypothesized to prevent future disorder, crime, and
neighborhood decline (Skogan, 1992). Broken windows strategies have proved popular among
police administrators and other local officials. In fact, perhaps no other recent academic theory of
crime has been as influential on public policy.
Underlying Theoretical/Empirical Justification & Historical Development
We start by reviewing the Broken Windows thesis’ historical development and assess the
key empirical and theoretical debates that have defined the approach. While discussions of urban
fear and disorder were occurring in the 1970s (Garofalo & Laub, 1978; Wilson, 1975), it was the
1982 publication of a nine-page article in The Atlantic that skyrocketed the broken windows theory
(BWT) into the mainstream (Wilson & Kelling, 1982). Crime during this time was high and
anxieties over public victimization prevailed (Wilson & Kelling, 1982). This is an important
backdrop because it suggests that society members were amenable to a change in strategy. Written
for a general audience, Wilson & Kelling’s piece laid out a logical case for why police ought to
pay greater attention to the minor disorders in urban communities to prevent future, more serious
harms. With this publication, Wilson & Kelling (1982) transformed an individual-level, cross-
sectional theory between disorder and fear into an ecological, longitudinal theory, whereby minor
disorders set in motion a process that leads to serious crime. As Wilson and Kelling (1982: 3) put
it: “at the community level, disorder and crime are usually inextricably linked, in a kind of
developmental sequence”. Wilson and Kelling’s (1982) asserted that incivilities in certain
neighborhoods caused law-abiding residents to avoid those places out of fear and conveyed a
message that “no one cares” about the neighborhood. Simultaneously, these incivilities signal to
local teens and at-risk youth that the area is ripe for delinquency (Taylor & Covington, 1993). On
these street blocks, the remaining concentration of residents with proclivities toward crime would
thus produce an increase in the frequency and severity of crime and other anti-social behaviors.
Overall, their model predicted crime would increase in areas with high levels of incivilities through
social psychological processes that reduced an area’s informal social control.
Wilson and Kelling’s ideas were rooted in Zimbardo’s (1969) famous study, which was,
similar to their piece, published in a mainstream outlet—Time Magazine. Curious how social
context affected individuals’ behavior, Zimbardo placed one vehicle each in the middle-class
neighborhoods of the Bronx (New York City) and Palo Alto (CA). Both cars had their license
plates removed and hoods opened. The car in the Bronx, near New York University, was almost
immediately the subject of pilfering, and soon vandals—described as clean-cut whites, families,
and children—all but destroyed the vehicle. In contrast, the car in Palo Alto—a vastly different
community from the Bronx—remained untouched for days until, according to Wilson and Kelling
(1982), Zimbardo smashed the car with a sledgehammer, and the car was subsequently vandalized
like its twin in the Bronx. Zimbardo concluded that the situations in which people find themselves
impact their conduct. In large and bustling areas like the Bronx, the collective sense of anonymity
in the streets encouraged law-breaking. In contrast, Palo Alto was a smaller, tightly-knit
environment characterized by concern for others. Only until the situation encouraged it—that is,
when Zimbardo introduced vandalism by taking a sledgehammer to the car—did others begin to
What accounted for the situations that produced disorder (or perceptions of disorder) that
began to worry Americans? Kelling and Coles (1997) argued that the proliferation of urban
disorder can be attributed to both the expansion of individual rights and to new models of policing.
To the former, they state: “the decriminalization of drunkenness and the deinstitutionalization of
the mentally ill has momentous consequences for our cities. Apart from increasing the level of
disorder on streets, these movements undercut the basic authority of police to intervene and
manage two important types of disorder (Kelling & Coles, 1997, p. 49).” Second, and buttressed
by the thought that foot patrol did not work, Kelling and Coles (1997) noted a paradigm shift in
policing toward a “warrior model”, whereby officers see themselves as crime-fighters who respond
to 9-1-1 calls in their vehicles. As a result, on-the-ground order maintenance activities were no
longer the focus. Taken together, in their view, these factors encouraged a context in which
disorderly behaviors were able to flourish.
Broken windows theory also may have been popular because its policy implications are
straightforward: reduce disorder by “taking the streets back” (p. 194) from the “disreputable or
obstreperous or unpredictable people: panhandlers, drunks, addicts, rowdy teenagers, prostitutes,
loiterers, the mentally disturbed” (p. 1). One need not spend much time thinking about how this
would be achieved given the order maintenance role of police from a not-too-distant past. Simply
get police officers out of their vehicles and onto the streets. Let them enforce not only laws, but
minor nuisances as well, even if they need to use a bit of extralegal cajoling in the process. After
all, the failure to strictly enforce minor disorders could—as proponents of the theory argue—lead
to much greater harms. Wilson and Kelling argued that the police were up to the challenge, and
soon after broken windows-based policing was implemented on a broad scale.
Evidence of Effectiveness and Theoretical Mechanisms
Empirical studies in the realm of broken windows can be distinguished by whether they
test theoretical propositions and mechanisms of the theory or whether they test the crime-reducing
impacts of broken windows-based policing tactics. Below, we first review the empirical status of
major theoretical tests, and then turn to research on broken windows-based policing . There is a
divergence between the conclusions of some of the theoretical tests and the applied evaluations.
Several years after the famous essay appeared in The Atlantic, Skogan (1992) posited a
version of the thesis, whereby incivilities trigger a process that leads to the decline of entire
neighborhoods. Unlike Wilson and Kelling (1982), Skogan bolstered his argument with data from
five large American cities that showed residents’ perceptions of physical and social disorder were
significantly associated with self-reported robbery victimization. Although BWT is longitudinal
and Skogan’s data were cross-sectional, his ultimate conclusion was that “both directly and
through crime it [disorder] plays an important role in neighborhood decline. ‘Broken windows’ do
need to be repaired quickly (p. 65).”
Harcourt (2005), however, reanalyzed Skogan’s (1992) data and found “no statistically
significant relationships between disorder and purse snatching, physical assault, burglary, or rape
when other explanatory variables are held constant (p. 78).” Harcourt reported that the association
with robbery was largely due to five neighborhoods in Newark, which became attenuated once
they were removed from the analysis. Harcourt (2005: 78) concluded “…the data do not support
the broken windows hypothesis.”
Taylor’s (2001) work in Baltimore partially supported the thesis by showing that minor
physical decay and social incivilities were linked to changes in some serious crime types.
Importantly, this work improved on past work by using a longitudinal design. Interestingly,
although Wilson and Kelling’s (1982) implied root causes need not be addressed, Taylor showed
that incivilities’ independent impacts on crime paled in comparison to the structural variables—
such as neighborhood status and racial composition—in his models. Taylor (2001) concluded:
“The broadest implication is that police planners and leaders should not automatically privilege a
program that focuses on the reduction of incivilities” (1996, p. 371).
A comprehensive discussion of the research assessing and critiquing specific elements of
BWT is beyond the scope of this chapter. For this reason, we adopt the useful knowledge-
organizing framework recently asserted by Wilcox, Cullen, and Feldmeyer (2017), who note that
empirical tests of BWT that have not found support of the theory generally fall within three
domains: (1) the “no-effect critique”—such as Harcourt’s findings discussed above; (2) the
“spurious effect,” and (3) the “perceptual critique.”
The most compelling version of the spurious critique, established by Sampson and
Raudenbush (1999), argued that crime and disorder—while indeed occurring together—are not
causally related. Rather, they state that both are the result of structural neighborhood forces and
collective efficacy—when residents trust each other more and are willing to intervene during
crimes or disorders. Sampson and Raudenbush offer strong evidence that the link between disorder
and crime is non-existent after controlling for collective efficacy and other key neighborhood-level
variables. A significant link, however, did survive between disorder and robbery (Sampson &
Raudenbush, 1999). They conclude that if disorder and crime are largely unassociated once shared
causes are introduced, then, in fact, the disorder-crime link can be said to be mostly spurious.
To the perceptual critique, a major challenge in disorder research centers on the need for
conceptual clarity regarding the nature of incivility and disorder (Kubrin, 2008). Challenging the
assumption that the perception of incivilities is an objective assessment of physical indicators of
disorder, a growing body of work has investigated how perceptions of incivilities are formed per
se and find that people define disorder differently. The weight of this research suggests that
incivilities are not universally defined in the way that BWT suggests (Carvalho & Lewis, 2003;
Franzini, Caughy, Nettles, & O’Campo, 2008; Harcourt, 2005; Sampson & Raudenbush, 2004).
Instead, disorder perceptions are shaped by many ecological, demographic, and psychological
factors, resulting in wide variation in perceptions among people in the same areas. For example,
Link and colleagues (2017) showed that perceptions of crime risk are more predictive of disorder
perceptions than the reverse formulation stated by BWT. In this way, people who are fearful of
crime go about their daily routine and more easily define things as disorderly. Overall, it is now
accepted that incivility perceptions are not merely a function of some true amount of incivilities,
but rather they are (1) influenced by neighborhood structure such as race and social class (Franzini
et al., 2008; Jackson, 2004; Sampson & Raudenbush, 2004; Wickes, Hipp, Zahnow, & Mazerolle,
2013) and (2) are therefore social constructions, at least in part (Hipp, 2010; Wallace, 2011). This
body of work raises serious construct validity issues for the fundamental cause in BWT.
In a related study, Gau and Pratt (2008) used factor analysis to critique BWT by showing
that “Citizens did not seem to differentiate between disorder and crime; rather, the two blended
together in their eyes” (2008, p. 181). If this is so, then the key independent variable of BWT may
not be distinguishable from its key outcome variable.
Overall, empirical tests of BWT have shown some, yet weak, support for the paradigm.
The theory employs independent and dependent variables that are very similar and have common
causes, it posits several mediating dynamics, and it rests on the assumption that specific urban
incivilities are universally perceived in the same negative light. For these reasons, among others,
it has been the subject of much empirical and theoretical criticism.
The above theoretical work is distinct from evaluations of disorder-based policing
strategies. Braga, Welsh, and Schnell’s (2015) recent meta-analysis of 30 experimental or quasi-
experimental studies, however, found that policing strategies with a disorder-reduction element
were associated with a statistically significant, modest reduction in crime (d = .210). Importantly,
the findings changed when they examined different styles of disorder policing: results remained
significant when approaches employed problem-solving approaches that sought to engage the
community and reduce crime in specific places, but programs that relied on aggressive policing of
individuals was no longer significant. Ultimately, Braga, Welsh, and Schnell (2015) concluded
“aggressive order maintenance strategies that target individual disorderly behaviors do not
generate significant crime reductions. In contrast, community problem-solving approaches that
seek to change social and physical disorder at particular places produce significant crime
reductions (p. 581).” As noted by the authors, however, this study does not speak to BWT’s
theoretical processes and causal mechanisms. In addition, many of the interventions employed
tactics such as problem-solving and hot spots policing. For these reasons, parsing out whether the
crime reduction benefits are attributable to core ideas of BWT or other policing strategies is
Next Steps for Scholarship on Broken Windows Policing
Untested Core Assumptions
None of BWT’s core features have been overlooked by social scientists. However, given
BWT is a complex longitudinal theory containing many indirect causal dynamics, only piecemeal
studies have been conducted. To date, there have been no longitudinal studies examining all of the
linkages between incivilities, fear, social withdrawal, reduced informal control, and increased
serious crime in one study. This analysis would be difficult to conduct and, given what we already
know from existing studies, perhaps unnecessary. Still, given the unprecedented influence of the
theory, it is somewhat surprising that a full evaluation has never been conducted. Moreover, since
researchers have yet to establish robust empirical tests of BWT in different contexts, external
validity remains an open empirical question. For example, one might question why the thesis may
be more supported in some areas and not others, such as the robbery effect seen in Newark, NJ
(Harcourt, 2005; Skogan, 1992).
Nevertheless, perhaps the most fundamental unresolved theoretical issue is what is meant
by incivilities and disorder and how they should be captured empirically (Kubrin, 2008). Despite
decades of scholarship, a few issues remain. First, researchers have used disparate terminology
and measures of incivilities and disorder (Kubrin, 2008). This may be unsurprising given what we
know about the difficulty of defining disorder (Harcourt, 2005). Second, and related, there is much
conceptual overlap between disorder and crime (Gau & Pratt, 2008) and other theoretical
constructs (e.g., social disorganization and collective efficacy). How BWT relates to these core
criminological ideas remains unclear. Third, research findings vary according to whether survey-
based perceptions of incivilities or researcher-assessed incivilities are used (Sampson &
Raudenbush, 1999; Taylor, 2001). Fourth, regardless of whether objective or subjective measures
of incivilities are employed, we also see variation in the extent to which individual disorder
indicators link with both crime and neighborhood structure outcomes longitudinally (Taylor,
2001), and we do not have a theoretical understanding for why. Finally, given the broken windows
thesis is an ecological theory, disorder would be best measured as a multi-level construct (Ward,
Link, & Taylor, 2017), yet little research has done so.
Nonethless, Braga, Schnell, and Welsh’s (2015) findings that disorder-reduction-based
approaches may be part of a package of police activities that can lower crime is promising.
However, what mechanisms are at play and whether they are attributable specifically to the
enforcement efforts that target incivilities and disorder remains an open question.
Collateral and Unintended Consequences
For years, scholars have documented many unintended consequences of the BWT
approach. In recent work, Kohler-Hausman (2018) directs our attention to a logical yet less-
discussed consequence of BWT-based policing: the overburdening of misdemeanor courts. Ill-
equipped to handle the huge increase in arrests produced in New York City, the court system
reacted by implementing a form of managerial justice that often appears very loosely related to the
traditional aims of court sanctioning. Others have honed in on important justice-related issues
associated with the implementation of disorder-based policing strategies, suggesting that the
practice produces racially disparate outcomes (Golub, Johnson, & Dunlap, 2007; Harcourt &
Ludwig, 2007). Relying on data from New York City, Golub, Johnson, and Dunlap (2007) argue
that marijuana use in public view was especially cracked down on during Giuliani’s BWT-inspired
quality-of-life initiative in the 1990s. Arrests for public marijuana use ballooned during this time
(Golub, Johnson, & Dunlap, 2007). More troubling, this increased enforcement was
racially/ethnically disproportionate, with blacks and Hispanics more likely to be arrested and
whites less likely (Golub, Johnson, & Dunlap, 2007). Although their data do not provide evidence
of overt racial discrimination, the disparity in and of itself should warrant concern and further
investigation, especially in the context of mass incarceration that disproportionately impacts
communities of color. Overall, reliance on enforcement tactics when implementing BWT policing
can create many concerns about consuming scarce criminal justice resources, creating disparities
in criminal justice outcomes, and adding to the criminal histories of many citizens.
Hot Spots Policing
Hot spots policing focuses police resources on micro-level high crime places with the goal
of reducing and preventing crime or disorder and/or improving citizens’ fear of crime, perceptions
of crime and disorder, or the police (Weisburd & Braga, 2006). “Resources” is an amorphous term
as it may mean increased police presence via automobiles (Taylor, Koper, & Woods, 2011) or foot
patrols (Ratcliffe, Taniguchi, Groff, & Wood, 2011), increased use of enforcement actions
(Sherman & Rogan, 1995), problem solving (Braga et al., 1999), or intelligence-led focus on high-
risk offenders (Groff et al., 2015). Places can include single addresses, street corners, street blocks,
or small areas or “grids”, but are usually smaller than a police administrative unit (Eck &
Underlying Theoretical/Empirical Justification & Historical Development
Hot spots policing developed from geographic criminology (Weisburd & Braga, 2006).
First, researchers continuously demonstrated that crime is disproportionally concentrated in a
select number of locations (Weisburd, 2015). While early studies demonstrated geographic
concentrations of crime in larger spatial units, such as region of a country (Groff, 2010), more
recent research found that crime concentrates at a disproportionate number of street blocks or
addresses (Groff, Weisburd, & Yang, 2010; Sherman, Gartin, & Buerger, 1989; Weisburd,
Bushway, Lum, & Yang, 2004; Weisburd, Groff, & Yang, 2012). The concentration of crime at
micro-places is so consistent across studies that the phenomenon is now referred to as the law of
crime concentration, which states that roughly 25% and 50% of crime will concentrate at just 1%
and 3% of spatial units in any city (Weisburd, 2015).
Multiple theoretical explanations emerged simultaneously to explain spatial crime
concentrations. One theoretical framework suggests spatial crime patterns are explained by local
social climate. Social disorganization theory first suggested that residents in economically
disadvantaged neighborhoods were more likely to move frequently and be of different racial/ethnic
backgrounds. As a result, residents were less “organized” or simply willing to engage in informal
social control (Shaw & McKay, 1942). Scholars continued to refine the social disorganization
perspective in response to critics (Bursik & Grasmick, 1993; Sampson, 2012), ultimately
suggesting that neighborhoods with higher collective efficacy will have lower crime (Sampson,
Raudenbush, & Earls, 1997).
Alternatively, environmental criminologists theorized that geographic crime
concentrations were due to concentrations of crime opportunities in certain areas. Cohen and
Felson (1979) defined opportunities as the spatial-temporal convergence of motivated offenders
and suitable targets lacking protection from capable guardians. Next, Brantingham and
Brantingham (1981; 1991) explained how physical space structures crime opportunities. The
Brantinghams argued the urban backcloth is comprised of nodes, pathways, and edges. Nodes are
places people visit, such as their homes, work, or favorite park. Pathways are the major
transportation routes in the city—or the street network and major public transportation routes.
Edges are the physical or perceptual boundaries between sections of a city, such as a major
thoroughfare between two neighborhoods. Everyone has an awareness and activity space.
Awareness spaces include everywhere in a city that people know about; whereas, activity spaces
include everywhere in a city people actually visit (Horton & Reynolds, 1971). As people move
across the urban backcloth during the course of their routine activities, they facilitate crime
opportunities. Thus, crime concentrates around nodes and along pathways and edges that are used
frequently, near offenders, and lack guardianship (Brantingham & Brantingham, 1993; 1999).
Environmental criminologists also theorize that offenders are rational decisions makers
(Clarke & Cornish, 1985; Cornish & Clarke, 1986). Rather than focus on only offenders’ decisions
to start, continue, and desist from offending, environmental criminology focuses on the decisions
that offenders make in the moments before, during, and after particular crime events (Cornish,
1994). Thus, regardless of whether offenders are on a planned crime trip or simply in the course
of their daily activities, offenders weigh the potential costs and benefits of offending, perhaps
imperfectly, and decide whether or not to offend in different contexts.
Evidence of Effectiveness and Theoretical Mechanisms
Leading policing experts agree that hot spots policing reduces recorded crime levels
(Braga, Papachristos, & Hureau, 2014; Skogan & Frydl, 2004). To date, studies have evaluated
police presence, police enforcement, problem solving, and offender-focused policing implemented
in hot spots. The first hot spots policing evaluation, the Minneapolis Hot Spots Policing
Experiment (MHSPE), assessed the impact of police presence on calls for service in hot spots
(Sherman & Weisburd, 1995). The study was in direct response to the Kansas City Preventive
Patrol Experiment, which suggested roughly doubly random patrols in geographically large police
beats had no measurable effects on crime (Kelling, Pate, Dieckman, & Brown, 1974). In short,
Sherman and Weisburd (1995) hypothesized police presence could deter crime if it was simply
implemented in higher dosages at geographically small locations. In the MHSPE, hot spots were
defined as clusters of addresses with at least 20 hard and 20 soft calls for service (CFS) in the
previous year that did not experience a 150% increase or 75% decrease in CFS from previous year
and were small enough so that the boundary was visible from the epicenter (Buerger, Conn, &
Petrosino, 1995). Random assignment split 110 qualifying hot spots into 55 treatment and 55
control locations. For the treatment, officers were asked to apply “crackdown-backoff” patrols.
Officers were free to answer calls for service and then return to the hot spots with visits lasting
anywhere from a few minutes to a few hours. Once the officers arrived in the hot spots, their
actions varied: “some were reading newspapers or sunning themselves while sitting on the patrol
car, while others were engaging citizens in friendly interaction in community-policing style”
(Sherman & Weisburd, 1995, p. 634). After roughly 6 months of implementation, CFS increased
significantly more in the control areas compared to the treatment areas.
A follow-up analysis of data from the MHSPE revealed the optimal patrol time in hot spots
was about 11-15 minutes (Koper, 1995). After 11-15 minutes, the impact of police presence in the
hot spots dissipated. Reflecting the survival models used in the analysis, Koper’s (1995) findings
became known as the “Koper curve”. Telep and colleagues (2014) later tested the Koper curve
using an experimental design in Sacramento (CA). Hot spot street blocks were randomly assigned
to 21 treatment and 21 control units. The treatment units were visited in a random order for about
15 minutes every 2 hours from 9:00 AM to 1:00 AM, 7 days a week. Officers were not provided
directions on specific actions to take within the hot spots, but were encouraged to make citizen
contacts, traffic or pedestrian stops, or business checks. During the 90-day treatment period, CFS
decreased by about 8% yet increased by about 11% in the control areas.
Foot patrols also have been used to increase police presence in hot spots. In Philadelphia,
60 hot spots were foot patrolled across two 8-hour shifts spanning 10:00 AM to 2:00 AM, Tuesday
through Saturday (Ratcliffe et al., 2011). In Newark, a single crime hot spot was foot patrolled
between 6:00 PM and 2:00 AM, seven days a week (Piza & O’Hara, 2014). In Kansas City four
hot spots were foot patrolled from 10:00 AM to 11:00 PM (Novak, Fox, Carr, & Spade, 2016). In
Dayton, 6 hot spots were foot patrolled in between officers’ normal duties for an average of about
9 hours of foot patrol across all hot spots per day (Haberman & Stiver, 2018). All of the evaluations
found hot spots foot patrol reduced violent or disorder crime by roughly 20 to 30%.
Police enforcement is the second tactic evaluated in hot spots. For example, during 6-hour
overtime shifts (7:00 PM to 1:00 AM), officers motor patrolled an 8 by 10 block high gun crime
police beat in Kansas City, MO with the goal of increasing gun seizures via vehicle and pedestrian
stops, traffic citations, and arrests. Compared to another high gun crime beat, 1,434 traffic and
pedestrian stops and 3,186 arrests or traffic citations led to a 260% increase in gun seizures and a
reduction of roughly 83 gun crimes (Sherman & Rogan, 1995). Two additional experiments found
crackdowns coupled with some non‐enforcement tactics, such as code enforcement, in Jersey City
drug markets linked to less disorder crime (Weisburd & Green, 1995) and proactive enforcement
in gun crime hot spots in St. Louis linked to less nondomestic firearm assaults (Rosenfeld,
Deckard, & Blackburn, 2014).
Problem solving is the third tactic evaluated in hot spots. In Jersey City, problem solving
relying on aggressive order‐maintenance policing and improvements to the physical environment
was implemented in 12 randomly selected hot spots. Relative to 12 control hot spots, reductions
were observed for the following outcomes during a 6-month follow-up period: (1) total incidents
and CFS, (2) street fighting CFS, (3) robbery incidents, (4) both property crime CFS and incidents,
and (5) narcotics CFS (Braga et al., 1999). Similarly, Braga and Bond (2008) evaluated the impact
of a combination of aggressive order‐maintenance policing, situational interventions, and social‐
service interventions across 17 treatment and control hot spots in Lowell. While the authors
described the problem solving efforts as “shallow”, total CFS as well as robbery, nondomestic
assault, and burglary CFS declined in the treatment hot spots. A mediation analysis revealed
situational interventions drove the total CFS reductions. A similar form of problem solving linked
to less violent crime in Jacksonville (Taylor et al., 2011).
Offender-focused policing (OFP) is the fourth tactic evaluated in hot spots. In Philadelphia,
OFP, PS, and foot patrol were implemented in 20 hot spots each with an additional 21 hot spots
serving as control areas. OFP included criminal intelligence and district officers identifying and
frequently making contact with offenders believed to live or offend within the OFP hot spots. An
evaluation ultimately suggested OFP reduced all violence and violent felonies by about 42% and
50%, respectively (Groff et al., 2015).
Theoretical Mechanisms of Evaluations
Hot spots policing tactics potentially reduce crime via numerous theoretical mechanisms.
Deterrence theory most commonly underpins the implementation of police presence and
enforcement, but may also explain how OFP reduced violent crime in Philadelphia. In practice,
however, police presence is often implemented by officers who naturally conduct a large number
of enforcement actions while on patrol in hot spots (e.g. see Ratcliffe et al., 2011). While officers
were not required to use enforcement actions by design (Groff et al., 2015), the OFP implemented
by the Philadelphia Police Department also likely included a large number of enforcement actions.
Finally, evaluations of problem solving in hot spots has often been called “shallow” due to the
predominant use of enforcement during implementation (Braga & Bond, 2008). Therefore, it is
equally plausible to suggest that risky offenders are frequently arrested and incarcerated due to hot
spots policing initiatives and incapacitation explains the effects observed during hot spots policing
evaluations. Of course, these theoretical mechanisms work at the offender-level, so they must
aggregate to ecological dynamics to explain hot spots policing effects. An alternative ecological
theory is that hot spots policing tactics impact collective efficacy, which in turn results in lower
crime. Research from St. Louis County suggests that link is at least plausible (Rinehart Kochel &
Weisburd, 2018). Additionally, when non-enforcement-based tactics are used, then situational
crime prevention principles (via environmental criminology) (Clarke, 1995) may explain the
effects observed in at least some hot spots policing evaluations.
Next Steps for Scholarship on Hot Spots Policing
Untested Core Assumptions
The numerous tactics and possible theoretical mechanisms means knowing for sure what
drives hot spots policing crime reductions difficult. Braga and colleagues’ (2014) meta-analysis,
however, provides some evidence that problem solving is most effective. As discussed above, most
problem solving implementations included numerous tactics, effectively resulting in a “black box”
treatment. While it would make sense that multi-faceted hot spots policing tactics are most
effective (Haberman, Groff, Ratcliffe, & Sorg, 2015) as they are consistent with police
commanders’ views of hot spots policing (Haberman, 2016), not knowing which tactics are most
effective for which reasons makes it difficult to make specific operational recommendations.
Relatedly, the long-term impact of hot spots policing is relatively unknown. Some tactics,
such as presence or enforcement, that work through deterrence or incapacitation may have short-
term effects. For example, Sherman’s (1990) initial and residual deterrence decay suggests
crackdown-style police presence and enforcement will have short-term effects, which was
supported by a follow-up analysis of the Philadelphia Foot Patrol Experiment (Sorg, Haberman,
Ratcliffe, & Groff, 2013).
Collateral and Unintended Consequences
Because hot spots policing often relies on police enforcement (Rosenbaum, 2006: 249-
250), the critiques of broken windows enforcement approaches described above can be applied to
hot spots policing too. Second, place-based enforcement may have impacts across the criminal
justice system, such as straining court systems and increasing bench warrants (see Goldkamp &
Vilcica, 2008). Third, critics might question the impact of hot spots policing on citizens’
perceptions (Rosenbaum, 2006). While police actions can have long-term impacts on residents
perceptions (Casper, Tyler, & Fisher, 1988), research to date has found relatively little change in
citizen perceptions due to hot spot policing (e.g., see Ratcliffe et al., 2015). Research that considers
hot spots policing’s effects on a range of outcomes spanning different units of analysis and stages
in the criminal justice system is needed.
On the other hand, one of the most anticipated unintended consequences of hot spots
policing, spatial displacement of crime (Rosenbaum, 2006), has been generally unsupported
(Braga et al., 2014). In fact, rather than generating spatial displacement, it is common for hot spots
policing actually to result in a diffusion of crime control benefits (Braga et al., 2014). Further,
when displacement is observed, it is often less than the observed crime control benefits (Ratcliffe
et al., 2011). Of course, spatial displacement is difficult to measure (Sorg et al., 2014; Sorg et al.,
2017), but the general takeaway is that empirical research is always needed to assess any potential
collateral or unintended consequences of hot spots policing as they ultimately may not hold true.
Focused Deterrence / Pulling-Levers Policing
Focused deterrence (FD) originated in Boston (Braga, Kennedy, Waring, & Piehl, 2001;
Kennedy, Piehl, & Braga, 1996; Kennedy, 1996), and is premised on the notion that only a small
percentage of the population is involved in firearm-related violence (Wolfgang, Figlio, & Sellin,
1972). Varying implementation of FD, however, have focused on three different target audiences
(Braga, Weisburd, & Turchan, 2018a): (1) group/gangs, (2) prolific offenders, and (3) drug
markets. Regardless of the target audience, FD usually proceeds as follows. First, the target
audience (gangs/groups, prolific offenders, or narcotics dealers) is identified using criminal
intelligence collected by local law enforcement (perhaps with the assistance of academic partners)
(Kennedy et al., 1996). After identification, the target audience is presented with two options: (1)
change their behavior by accessing social services and reconsidering their lifestyles and behaviors
or (2) face elevated law enforcement focus. Members of the target audience who receive law
enforcement focus are typically assured two things: (1) everything possible will be done to ensure
they will receive criminal prosecution and (2) everyone involved (especially when a member of a
group/gang) will receive criminal prosecution as the result of any future violence (Kennedy, 2011).
These messages and options have been predominantly delivered via “call-in sessions”.
Call-in sessions are typically conducted in a court-room or other government/community office by
local government and criminal justice officials and community members (Kennedy, 2011).
Additionally, some jurisdictions have also used custom notifications to deliver the message
directly to select individuals (Engel, Tillyer, & Corsaro, 2013). Custom notifications involve
visiting individuals at their homes (or other locations) (Kennedy & Friedrich, 2014). After the
target audience has received the focused deterrence message, the expectation is that the recipients
will decide that engaging in firearm-related violence is not worth the potential risk (Tillyer, Engel,
& Lovins, 2012). The target audience can then change their lifestyle (by requesting social services)
and/or dissuade each of their members from engaging in violence.
Underlying Theoretical/Empirical Justification & Historical Development
David Kennedy, Anne Piehl, and Anthony Braga developed FD in Boston in the 1990s
during the Boston Gun Project (Braga et al., 2001; Kennedy, 1996; Kennedy et al., 1996). Kennedy
(2011) described FD’s development as somewhat happenstance. In short, Boston Police
Department officers relayed their insights to Kennedy, Piehl, and Braga during fieldwork, and they
then connected those ideas into a single, overall gun violence reduction strategy.
Seven ideas underpinned FD’s development (see Kennedy et al., 1996; Kennedy, 1996;
Kennedy, 2011, Chapter "Cincinnati"). First, Boston police officers emphasized that only a small
number of gang-involved offenders were responsible for the majority of gun violence. Of course,
that idea was entirely consistent with Wolfgang and colleagues’ (1972) seminal work showing
roughly 6% of the population was responsible for roughly 50% of criminal offending (also see
Piquero, Farrington, & Blumstein, 2003). Relatedly, it was shown that gang-involved youth were
also more likely to be the victims of gun violence as well. Second, gun violence mostly results
from “petty beefs” stemming from relatively minor disagreements as opposed to largescale
drug/turf battles. Third, there are often many opportunities to use law enforcement against gang-
involved youths that may potentially go unused (e.g. drug dealing, public drinking, etc.), and
enforcing those simultaneously could lead to a much greater deterrent effect. Fourth, if deterrence
was going to work, then potential offenders needed to know about the possibility of enforcement
and direct means of communication should be used to inform them. Fifth, it was believed that
offenders also needed to understand that enforcement would be focused on all gang members as a
response to any member’s involvement in violence. Sixth, it should be conveyed to potential
offenders that the strategy was designed to protect them from violence even if they did not protect
themselves. Seventh, the police and others on the FD team would be willing to leverage resources
to assist those ready for desistance. Overall, these ideas represented a departure from the
conventional thinking on gun violence at the time and provided the impetus and foundation for the
FD components previously outlined. Stated differently, FD’s components stemmed directly from
the shift in thinking developed during the Boston Gun Project.
Evidence of Effectiveness and Theoretical Mechanisms
Evidence showing FD reduces gun violence originates with Boston’s Operation Ceasefire
(Braga et al., 2001). Given Operation Ceasefire was implemented citywide, Braga and colleagues
(2001) used time series count regression models to examine how the number of homicide victims
aged 24 years or younger, shots fired, calls for service, and gun assault incidents changed during
implementation. All three outcomes were statistically significantly lower during the
implementation period: (1) youth homicides by 63 percent, (2) citywide shots-fired calls for
service by 32 percent, and (3) citywide gun assault incidents by 25 percent. Replications in
Indianapolis (McGarrell, Chermak, Wilson, & Corsaro, 2006), Stockton (Braga, 2008), Lowell
(Braga, Pierce, McDevitt, Bond, & Cronin, 2008), Cincinnati (Engel et al., 2013), New Orleans
(Corsaro & Engel, 2015), and Bridgeport (Sierra-Arevalo, Charette, & Papachristos, 2017) have
produced similar findings.
FD also influences gang-level violence. Boston re-implemented FD in 2007 (Braga,
Hureau, & Papachristos, 2014). An analysis using propensity score matching (PSM) to identify
comparison gangs and growth curve regression models suggested FD reduced shootings by
roughly 31% among the gangs receiving the FD treatment relative to the comparison gangs. A
follow-up study design suggested Boston’s second FD initiative also reduced shootings among
untreated gangs within the treated gangs’ social networks (i.e., vicariously treated gangs) by about
24% relative to a set of comparison gangs. A Chicago study reported similar findings (Papachristos
& Kirk, 2015).
A third set of evaluations have examined how FD impacts individual-level violence. As
part of Chicago’s Project Safe Neighborhoods grant, parolees with a history of weapons offenses
attended FD-based call-in sessions, which resulted in lower neighborhood gun violence levels
(Papachristos & Kirk, 2015). In an international context, FD reduced stabbings among gang-
involved youth in Glasgow (Williams, Currie, Linden, & Donnelly, 2014). A major criticism of
FD evaluations is that they have long relied on quasi-experimental evaluations (Braga, Weisburd,
& Turchan, 2018b). Recently, however, there has been an experimental evaluation of FD at the
individual level in Cambridge, Everett, and Somerville, MA (Uchida et al., 2018). First, a social
harm “risk score” was developed to identify people at risk of gun violence. Next, the individuals
with the top 150 risk scores were blocked into three groups of 50 by rank and randomized into the
treatment or control groups within each cohort. The treatment group individuals were then invited
to a standard notification meeting (i.e., a call-in) where the FD message and an offer of social
services were delivered. Additionally, the treatment group received “intensive supervision and
enforcement activities in the community” (pg. 7). The control group received no additional police
focus. Survival models showed no difference in the time to arraignment between the treatment and
control groups, which may have been due to a relatively low dosage (Uchida et al., 2018).
Other studies have evaluated FD’s impact on drug markets/dealers. The High Point (NC)
Drug Market Initiative (DMI) was the first application of FD to open-air drug markets/dealers
(Corsaro, 2013). FD DMIs are implemented slightly different from group initiatives. In DMIs, law
enforcement invests resources in narcotics investigations prior to the first call-in. After the
investigations have been completed, the DMIs usually result in a series of arrests for offenders
with violent pasts. The remaining un-arrested narcotics dealers are called-in where evidence of
their illegal behavior is presented along with the focused deterrence message and offers for social
services. Time series analyses for the neighborhoods where DMIs were implemented suggested
violence in High Point (Corsaro, 2013) and drug incidents in Nashville (Corsaro, Brunson, &
McGarrell, 2010) were reduced.
Theoretical Mechanisms of Evaluations
Again, deterrence theory underpins FD. Offenders are assumed to weigh the benefits, costs,
and risk of offending, and refrain from offending when the costs/risks are too high. FD is
predicated on communicating the risks of apprehension to offenders via a “retail deterrence
message” (Braga et al., 2001). The inclusion of federal law enforcement partners is a means by
which to increase offending costs as federal sentences tend to be longer and located in faraway
institutions where inmates are less likely to be visited. When targeted individuals fail to adhere to
the FD message, the immediate enforcement actions that follow can be viewed as a means of
demonstrating increased certainty (e.g., see the enforcement response schedule in Roman, Link,
Hyatt, Bhati, & Forney, 2018). Overall, FD is purported to work by warning potential offenders
how law enforcement will come after them if they engage in violence and then come after in those
exact ways if offenders self-select into enforcement by failing to refrain from violence.
It would be remiss to ignore the fact that FD may also work via incapacitation (Zimring &
Hawkins, 1995). Law enforcement is an important component of many FD initiatives (Braga et
al., 2008; see Figure 2 in McGarrell et al., 2006). For example, a YouTube search for “Cincinnati
Initiative to Reduce Violence” will return numerous media reports showing “gang roundups” (see
Engel et al., 2013). It is possible that FD initiatives have worked by simply getting high-risk
offenders off the street, which is an important goal for police commanders (see Haberman, 2016).
Recall FD DMIs have used intensive narcotics investigations from the beginning (Corsaro &
McGarrell, 2009; Corsaro, Brunson, & McGarrell, 2009). In short, it is possible that FD initiatives
work by incapacitating a city’s most active offenders.
Finally, FD may reduce crime via improvements in police legitimacy (see Pratt & Graham,
this volume). Theorists suggest that people who perceive the police as more legitimate are more
likely to obey the law (Tyler, 2004; Tyler, 2006; Tyler & Fagan, 2008). Police legitimacy is shaped
by the perception that the officers treat people fairly and justly during encounters. It follows that
FD may increase police legitimacy. Rather than rely on indiscriminate enforcement actions to
reduce crime, FD focuses selectively on the highest-risk individuals. Further, call-in sessions
communicate directly to those individuals that community members want to help them “get out of
the life” and will only use enforcement actions if the individuals are directly engaged in violence.
Individuals targeted during FD should know exactly why they received police focus. In Chicago,
call-in sessions were even designed with three specific legitimacy increasing components: (1) call-
in sessions were held in neighborhood institutions as opposed to criminal justice sites, (2) seats
were arranged in a circle to make the sessions more communal, and (3) the FD message was
organized to promote equality and rationality to all participants—particularly with an emphasis on
helping the participants better their lives (Papachristos & Kirk, 2015; Wallace, Papachristos,
Meares, & Fagan, 2016). Thus, rather than deterring offenders via risk of apprehension, FD may
encourage offenders to refrain from offending by increasing their perceptions of police legitimacy.
Next Steps for Scholarship on Focused Deterrence
Untested Core Assumptions
Despite a large body of supporting evidence, there remains a number of important
limitations of FD. First, FD largely remains a black box. Those seeking information on FD are left
piecing together the details of each implementation from published materials. FD evaluation
reports detail implementation differently, with relatively minimal details about dosage (for an
exception see Roman et al., 2018). As a result, little is known about which components are vital
for FD to be successful or which theoretical mechanisms drive the effects.
The complexity of FD likely explains why it is difficult to sustain (Engel, 2018; Henderson
& Ozer, 2017). A lack of model fidelity over time (e.g., programs straying from successful tactics
due to funding cuts, politics, etc.) or problems with consistently identifying and delivering the
strategy to high risk individuals creates obstacles to continued success with the FD model
(Henderson & Ozer, 2017). Some cities, such as Cincinnati, Boston, and New Orleans, have seen
violence increase following initial successes (Corsaro, Ozer, Haberman, & Engel, 2017;
Henderson, Peterson, & Engel, 2017; Kennedy, 2011).
Finally, FD assumes high-risk offenders can be accurately identified via criminal
intelligence (i.e., clinical prediction) or a risk assessment model (i.e., actuarial prediction) during
a period that is useful for implementation. To some extent that is likely a reasonable assumption,
especially when FD is implemented for gang violence (Papachristos, Braga, Piza, & Grossman,
2015), but evaluations of the accuracy of criminal intelligence or risk assessment models for gun
violence are virtually non-existent. If police departments begin using predictive models for
selecting FD targets (e.g., Saunders, Hunt, & Hollywood, 2016), then questions of accuracy and
the other criticisms of predictive policing become quite relevant (Ferguson, 2017; Underwood,
Collateral and Unintended Consequences
While we note that FD could improve legitimacy by focusing more selectively on prolific
offenders, it is also possible that it can decrease police legitimacy. For example, the relative
emphasis on social service and enforcement components likely varies across sites. In Philadelphia,
the intervention relied on several enforcement levers not normally used, such as working with local
utility companies to shut off gas and electricity at members’ residences and initiating public
housing evictions (Roman et al., 2018). Though creative, it is plausible that some of these newly-
invented levers—especially the ones that affect the lives of the family members of gangs and others
not involved in gangs (such as shutting off power)—may inspire further mistrust and resentment
among the community, police, and other government agencies.
The group focus in FD may also result in net-widening. While many group members
certainly self-select into FD, periphery members may find themselves the focus of law
enforcement despite being relatively trivial players. In fact, one might argue that relatively minor
offenders are easy to engage in enforcement against compared to the high-level offenders who are
more insulated from street-level activity. As a result, it is plausible FD enforcement actions are
focused on people who may not otherwise become the focus of law enforcement. Moreover, the
worst offenders may simultaneously evade law enforcement action.
Finally, the processes by which law enforcement identify and label individuals as gang
members or affiliates in databases deserves further scrutiny. Bringing to light what these processes
are, how they vary across jurisdictions, whether they are accurate (i.e., align with other measures
of membership), what mechanisms are in place to remove someone from a list and how frequently
this occurs are all examples of understudied questions that hold critical implications for the lives
and liberty of the people identified as a gang member or affiliate.
This chapter reviewed three dominant policing strategies: (1) Broken Windows Policing,
(2) Hot Spots Policing, and (3) Focused Deterrence. For each, the strategy’s definition,
development, evidence, underlying theoretical mechanisms, and current limitations were
reviewed. This chapter illustrated areas for development within each strategy as well as areas
where further development is needed to integrate innovative policing strategies and policies within
the wider scope of the criminal justice system and criminal justice theorizing.
While each strategy’s review provides insight into its past and needed future development,
the reviews collectively can provide additional insights on the future of policing effectiveness and
the criminal justice system. First, we demonstrated criminological theory underpins each policing
strategy, which is promising for rational policymaking (Mears, 2007). However, it also reiterates
the importance of closely coupling basic science developing criminological theory and applied
science developing and evaluating policy. While the field has not always viewed applied research
as favorably or prestigious as basic science (Cullen & Gendreau, 2001; Kraska, 2006), it follows
that the divide between theoretical and applied crime research is neither real nor helpful if society
cares about controlling crime. Under a rational policy-making framework, we would have
theoretical explanations of crime (regardless of unit of analysis) and corresponding crime control
policies that directly address the causes of crime. In effect, criminological theory explaining crime
is the foundation for any potential criminal justice theories that seek to explain how society
responds to crime. Perhaps, persuading basic scientists on the need to ultimately contribute to
policy discussions will result in work with more direct policy implications. This may even help
alleviate the feeling among academics that their work is not taken seriously by society.
Environmental criminologists have been particularly adept at developing and testing theories with
crime control in mind and may provide a good model in the future (Cullen, 2011). Moving forward,
a perspective that views the two traditionally separate lines of inquiry as one integrated focus will
be vital for developing theoretically-based, fair, and effective crime control policy.
Developing theoretically and empirically sound policy models, however, will be only the
first step. Not enough is known about the adoption and implementation of policing strategies in
practice. In other words, what influences police organizations to adopt a particularly strategy, such
as focused deterrence? Is it as simple as a policy showing promising results that a politician learns
about (Kennedy, 2011, Chapter "Cincinnati")? Moreover, how do politics interact with police
commanders’ views? Do police commanders resist politicians in some cases but acquiesce in
others? What factors ultimately influence police officers and commanders on which strategies are
effective and should be adopted? Organizational theory and closer analysis of the incentives that
drive large scale policy adoptions across police departments should help us understand these
dynamics (Katz, 2001), as will studies that directly ask practitioners about their views and
receptivity to different strategies (Haberman, 2016; Telep & Lum, 2014; Telep & Winegar, 2015).
Overall, developing and testing theories—perhaps influenced by current organizational theories
(see King, 2009; Matusiak, King, & Maguire, 2017)—is needed to advance criminal justice theory
and the field’s understanding of fair and effective policing.
Of course, the police exist within the larger criminal justice system. The police are
influenced by what happens earlier and impact what happens later in the criminal justice process
(Gottfredson & Gottfredson, 1989; The President's Commission on Law Enforcement and
Administration of Justice, 1966). Moreover, many new policing strategies, such as hot spots
policing and focused deterrence, require police departments to work collaboratively with
organizations both inside and outside the criminal justice system. Relatively little is known about
what makes these partnerships successful. For example, are successful partnerships between local
and federal law enforcement due to interpersonal relationships among law enforcement
professionals, a common belief in the effectiveness of a strategy, or organizational or political
accountability mechanisms that “force” different agencies to work with each other? Or how does
law enforcement’s perceptions of the courts and sentencing impact the strategies they use? For
example, prosecutors are often blamed by the police for throwing too many cases out while the
police are often blamed for assembling weak cases for prosecutors. Do these dynamics have long-
term impacts on which strategies police adopt? If other criminal justice agencies are needed to
implement a policing strategy, like in focused deterrence, will poor relationships among agencies
prevent that strategy from ever being implemented? These are only some of the questions that will
be relevant for understanding policing strategies in the future, but ultimately illustrate the
importance and need for theorizing that explains how police departments existence and
interactions within the larger criminal justice system policing strategies.
Finally, the emergence of “big data” and analytics in policing (Ferguson, 2017; Ridgeway,
2018) will undoubtedly shape the future. Analytical insights, such as the concentration of crime
within places and people, helped shaped innovative policing strategies, such as hot spots policing
and focused deterrence. Police academics have developed a large number of three-word policing
strategies, and many police officials have seen the “strategy du jour” come and go. Further
theorizing and explanation of changes in policing strategies within the context of the points made
above would also be useful. Understanding why fads come and go in policing may have
implications for catalyzing reforms in the future.
With that said, one could question if what policing really needs is organizational models
that integrate crime and intelligence analysis into decision-making to address crime and other
social ills. It may be that organization structure, accountability mechanisms, and leadership are
most important to the adoption and implementation of effective policing tactics/strategies. In other
words, rather than always attempting to fit policing into a three-word policing strategy, the focus
could be on organizational changes that create analytic-driven decision-making. The development
and testing of theories of organizational change and decision-making would likely have a long-
term impact on police reform.
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