An Integrated Theory of Hot Spots Patrol Strategy

AuthorNeil Wain,Lucinda R. Strang,Barak Ariel,Lawrence W. Sherman,Molly Slothower,Stephen Williams,Andre Norton
Date01 May 2014
Publication Date01 May 2014
/tmp/tmp-17ptga2BA01LZ3/input 525082CCJXXX10.1177/1043986214525082Journal of Contemporary Criminal JusticeSherman et al.
Journal of Contemporary Criminal Justice
2014, Vol. 30(2) 95 –122
An Integrated Theory
© 2014 SAGE Publications
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of Hot Spots Patrol
DOI: 10.1177/1043986214525082
Strategy: Implementing
Prevention by Scaling
Up and Feeding Back
Lawrence W. Sherman1,2, Stephen Williams3,
Barak Ariel1,4, Lucinda R. Strang5, Neil Wain1,
Molly Slothower2, and Andre Norton3
In late 2013, Trinidad and Tobago Police Service (TTPS) conducted the first
randomized experiment ever to test a hot spots patrol strategy (HSPS) across
large areas, as distinct from testing extra patrols one hot spot at a time. The HSPS
experiment required, and helped to refine, a formal theory of both the causes and
effects of directed patrols in hot spots. This article presents an integrated theory of
how to implement an HSPS in ways that maximize the preventive effects of patrol on
crime. It then describes the HSPS experimental protocol used to test the theory in
Trinidad. The key elements of HSPS are scaling up from specific hot spot locations to a
district-wide focus on all its hot spots and feeding back to the constables who provide
hot spots patrols data on what they have done and with what effect—presented
every 2 weeks, at a district-level “COP-stat” meeting with the people actually doing
the patrols.
Hotspots, Patrol Dosage, Residual Deterrence, Displacement, Koper Curve
1University of Cambridge, UK
2University of Maryland, College Park, USA
3Trinidad and Tobago Police Service, Port of Spain
4Hebrew University of Jerusalem, Israel
5Cambridge Centre for Evidence-Based Policing, UK
Corresponding Author:
Lawrence W. Sherman, Institute of Criminology, Jerry Lee Centre of Experimental Criminology,
University of Cambridge, Sidgwick Avenue, Cambridge, UK.

Journal of Contemporary Criminal Justice 30(2)
How can police reduce crime and disorder in public places? One answer is hot spots
policing. That answer, however, says more about a theory of the effects of increased
patrols in hot spots (Reiss, 1985; Sherman, 1990; Sherman & Weisburd, 1995) than
about a theory of the causes of those patrols. A theory of how to cause patrols to occur is
described by police leadership as a sustainable strategy for implementing and maintain-
ing a measureable level of patrols—but the strategy is essentially a theory of how to
cause the causes of crime reduction. Although strategies must be flexible in response to
unanticipated obstacles, they must also have a clearly structured vision of the links in a
causal chain of actions that delivers coordinated organizational behavior, a theory of
implementation that drives daily operations.
Despite a flourishing body of research (if not formal theory) on the effects of hot
spots policing (Braga, Papachristos, & Hureau, 2012), there is neither theory nor evi-
dence on what actions police leaders should take to create and maintain the causes of
a successful hot spots patrol strategy (HSPS). Criminologists are usually more inter-
ested in crime than in organizational behavior. Yet, the applied criminology of police
management requires that a theory of crime reduction be based on an evidence-based
theory of what works in leading police service delivery on a large scale, eventually
covering any part of a jurisdiction where crime is concentrated into hot spots.
The local effects of hot spots policing at hot spots may be well-established, but the
police profession remains openly skeptical about the issue of displacement. There is
good reason for the skepticism, on two grounds. One is that the substantial evidence
against displacement (Braga et al., 2012; Weisburd et al., 2006) is place-based not
offender-based. Until some police see evidence that offenders are not going from areas
targeted by extra patrols to areas of less patrol, they may remain unconvinced that a
hot spots strategy can reduce total crime in a jurisdiction—or even a police district.
The second basis for their skepticism is that hot spots policing has never been clearly
tested at a district level. “Scaling up” the testing and delivery of hot spots at that level
is needed to show district commanders, at least, that when they target hot spots for
directed patrol, the total crime across the district will be lower—even if it displaces
crime or criminals out of the district.
Although a hot spots strategy has never been tested at a district level, it must be
delivered at that level to demonstrate the full benefits, which are only implied by the
theory and evidence we already have—but not yet tested. It is essential, then, to scale
up the evidence along with the delivery to test hot spots policing at a district level,
using districts as the units of analysis in randomized controlled trials. It is only when
we have evidence on the effects of more patrolling at every hot spot of crime in public
places, and not just a random selection of them (e.g., Ratcliffe, Taniguchi, Groff, &
Wood, 2011; Sherman & Weisburd, 1995), that we can address the skepticism. That
evidence is impossible to generate, we suggest, without a theory of the causes of con-
sistently higher patrol levels in every hot spot, on a long-term, sustainable basis.
The development of this evidence requires a clear distinction between a theory of
effects and a strategy for creating causes of those effects. A theory of how certain

Sherman et al.
causes create certain effects is an integrated set of propositions that specifies and pre-
dicts the relationships between actions and results. It includes both necessary and suf-
ficient conditions by which X causes Y. It need not specify how X happens, or how to
cause X to happen. It merely predicts that if X does happen, Y will result. A strategy
is, in effect, a theory of how to cause the causes to occur: a plan for organizing the
actions of many people to take many steps in a specified sequence to implement and
apply a theory of cause and effect. It is just as focused on the causes of X as it is on the
effects of how X causes Y. In hot spots terms, a strategy of hot spots policing must be
primarily concerned with how to insure that police patrols are conducted in the way
the theory predicts will reduce crime, on the assumption—or evidence—that such
patrols will keep crime levels lower than they would be under a strategy of random,
undirected, “omnipresent” patrol (Wilson, 1950).
A strategy is thus simply another kind of theory. It requires integrated propositions,
but its focus is on the production of the independent variable (as organizational out-
) rather than on the effects of the independent variable on the dependent variable
(as organizational outcomes, such as less crime and disorder). Put another way, it is
about the “causes of the causes” of crime reduction (Wikstrom, Oberwittler, Treiber,
& Hardie, 2012). A police management strategy—a theory of causing causes—is
required to cause police to do what a criminological theory says is required to reduce
The idea of strategy as a theory suggests the value of an “integrated” theory of hot
spots patrols, in which the causes of the patrols are linked to the causes of crime and
disorder reduction. In this article, we re-state and formalize the developing theory
(Braga & Weisburd, 2010; Sherman, 1990; Sherman & Weisburd, 1995) of how hot
spots patrols can reduce crime, as informed by extensive evidence. We then link that
theory of outcomes to a new theory of outputs: How police management can cause and
sustain hot spot patrols. By linking a management strategy for transforming patrol
practice to implement the hot spots theory, we may build a translational theory of
application into a formal theory from the outset. We then describe the protocol for test-
ing the strategy in the Trinidad and Tobago Police Service (TTPS) and briefly sum-
marize the early implementation of the test. We conclude by reflecting on the time
frame required to move any police agency from a discretionary to a directed patrol
strategy against violent crime.
The goal of this article is to address the central challenge of providing a continu-
ously high dosage of intermittent patrol at predictable crime hot spots in a global
context of inadequate attention paid by police management systems to where and
when patrol dosage is delivered on a daily basis. The article has five sections as
1. A Hot Spots Patrol Theory of Causing Crime Reduction Effects
2. A Strategy for Implementing Hot Spot Patrols
3. A Protocol for an Experiment in HSPS
4. A Preliminary Report on Implementing the Protocol in Trinidad
5. Strategic Planning and Evidence-Based Policing

Journal of Contemporary Criminal Justice 30(2)
A Hot Spots Patrol Theory of Causing Crime
Reduction Effects
The theory of the crime reduction effects of police patrol is derived from both (a) the
classic doctrine of deterrence, and (b) modern evidence on police innovations. Taken
together, these sources provide an opportunity for refining key concepts as the basis
for a theoretical statement. These 18 key concepts will ideally become a standard
vocabulary for the highly precise “rocket science”—not just vague principles—of hot
spots patrols. The concepts are hot spots, local deterrence, local displacement, regional

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