U.S. Department of Justice 

Office of Community Oriented Policing Services 

COPS Logo
Campbell Collaboration LOGO
Department of Justice LOGO

Anthony A. Braga, Ph.D. 
Program in Criminal Justice 
Policy and Management 
John F. Kennedy School of 
Government, Harvard University 
Police Enforcement Strategies to 
Prevent Crime in Hot Spot Areas 
No. 2 
The Campbell Collaboration LOGO
The Campbell Collaboration Crime and Justice Group LOGO


Suggested citation: 

Braga, Anthony A. Crime Prevention Research Review No. 

2: Police Enforcement Strategies to Prevent Crime in Hot Spot 
Areas. Washington, D.C.: U.S. Department of Justice Office 
of Community Oriented Policing Services, 2008. 

The opinions contained herein are those of the author and 
do not necessarily represent the official position or policies 
of the U.S. Department of Justice. References to specific 
companies, products, or services should not be considered 
an endorsement by the author or the U.S. Department of 
Justice. Rather, the references are illustrations to supplement 
discussion of the issues. 

Cover crime-mapping illustration by Thomas Beretich.
Copyright 2008, DWI Resource Center, Inc.

The Campbell Collaboration Crime and Justice Group 
(http://campbellcollaboration.org/ccjg) is an international 
network of researchers that prepares, updates, and rapidly 
disseminates systematic reviews of high-quality research 
conducted worldwide on effective methods to reduce 
crime and delinquency and improve the quality of justice. 

The Campbell Collaboration The Campbell Collaboration 
Crime and Justice Group 


Contents 

Acknowledgments ..............................................v 
Introduction .................................................5 
Identifying Evaluations of Hot Spots Policing Programs. . . . 9 
Characteristics of Hot Spots Policing Programs ...............13 
Effects of Hot Spots Policing Programs on Crime and Disorder .17 
Displacement and Diffusion Effects. . . . . . . . . . . . . . 21 
Conclusion and Policy Implications ...........................23 
References ...................................................27 

iii 

Acknowledgments 

This research was supported by funds from the Smith Richardson Foundation. The author 
thanks Phyllis Schultze of Rutgers Universitys Criminal Justice Library and Deborah 
Braga of the University of Massachusetts  Amherst for their assistance in completing the 
review. David Weisburd, David B. Wilson, Anthony Petrosino, Larry Sherman, Brandon 
Welsh, David Farrington, Matthew Lysakowski, and the anonymous reviewers also deserve 
thanks for making helpful comments on earlier iterations of this review. This paper briefly 
reviews the research on the crime-control effectiveness of hot spots policing programs. 
Readers interested in a more detailed assessment of the crime-prevention value of hot spots 
policing programs should refer to earlier published works (Braga, 2001, 2005) or consult 
the Campbell Crime and Justice Group web page for updated reviews (www.aic.gov. 
au/campbellcj/). 

A note regarding the Crime Prevention Research Review Series 

The research included in this Crime Prevention Research Review is limited to studies that 
use experimental or quasi-experimental designs and meet the criteria for rigor as laid out 
in The Campbell Collaboration Crime and Justice Group review criteria (see http://www. 
campbellcollaboration.org/guidelines.asp). It is important to note that other pieces of 
evidence regarding the effectiveness of various strategies were excluded from this research. 
The popular series of Problem-Oriented Guides for Police (POP Guides) published by the 
Office of Community Oriented Policing Services (the COPS Office) differs significantly 
from this review because the standards for inclusion of evidence are less tied to the use of 
experimental designs and thus include a wider range of evidence. 

Police Enforcement Strategies to Prevent Crime in Hot Spot Areas is the second in the 
Crime Prevention Research Review Series. The first publication in the series is Disrupting 
Street-Level Drug Markets. Both are available from the COPS Office, www.cops.usdoj.gov. 

v 

Given the growing popularity of this approach to 
crime prevention, a review of existing evaluations 
of hot spots policing programs can help police 
executives and policymakers understand what 
works in preventing crime in hot spot areas. 

Introduction 


Introduction 

Hot spots policing has become a very popular way for police departments to prevent 
crime. A Police Foundation report found that 7 in 10 departments with more than 100 
sworn officers reported using crime mapping to identify crime hot spots (Weisburd et al., 
2001). Recent research studies suggest that focused police interventions, such as directed 
patrols, proactive arrests, and problem-oriented policing, can produce significant gains in 
crime prevention at high-crime hot spots (Eck, 1997, 2002; Braga, 2002; Weisburd and 
Eck, 2004). Given the growing popularity of this approach to crime prevention, a review 
of existing evaluations of hot spots policing programs can help police executives and 
policymakers understand what works in preventing crime in hot spot areas. 

Police officers have long recognized the importance of place in crime problems. Police 
officers know the locations in their beats that tend to be trouble spots and are often very 
sensitive to signs of potential crimes across the places that comprise their beats. As Bittner 
(1970) suggests in his classic study of police work, some officers know the shops, stores, 
warehouses, restaurants, hotels, schools, playgrounds, and other public places in such a way 
that they can recognize at a glance whether what is going on within them is within the range 
of normalcy. At the organizational level, the traditional police response to such trouble 
spots typically included heightened levels of patrol and increased opportunistic arrests and 
investigations. Until recently, police crime-prevention strategies did not focus systematically 
on crime hot spots and did not seek to address the underlying conditions that give rise to 
high-activity crime places. 

Unlike most innovations in policing, the emergence of hot spots policing can be traced 
to the development of computerized mapping and database technologies and the growing 
academic interest in the importance of specific places in understanding crime problems 
(Weisburd and Braga, 200 ). During the late 1980s and early 1990s, a number of research 
studies documented that crime is not spread evenly across city landscapes; rather, that 
crime clusters in very small places, or hot spots, that generate a disproportionate amount 
of criminal events (Pierce et al., 1988; Sherman, Gartin, and Buerger, 1989; Weisburd et 
al., 1992). In Minneapolis, for instance, only 3 percent of the citys addresses accounted 
for 50 percent of calls for service to the police (Sherman, Gartin, and Buerger, 1989). 


In Jersey City, about 4 percent of streets and intersection areas generated nearly half of 
the citys narcotics arrests and almost 42 percent of the disorder arrests (Weisburd and 
Green Mazerolle, 2000). Even in the most crime-ridden neighborhoods, crime clusters in 
a few discrete locations, while other areas are relatively crime free (Sherman, Gartin, and 
Buerger, 1989). A number of police policymakers and researchers have suggested that many 
crime problems can be reduced more efficiently if police officers focused their attention 
to these deviant places (Sherman and Weisburd, 1995; Weisburd and Green, 1995). The 
appeal of focusing limited resources on a small number of high-activity crime places is 
straightforward. If we can prevent crime at hot spot locations, then we might be able to 
reduce total crime. 

Hand-developed pin maps have been used widely in police departments for more than half 
a century (Weisburd and McEwen, 1997) and there are isolated examples of what today 
would be defined as hot spots policing in earlier periods (Weiss, 2001). A recent study by 
Weisburd and Lum (2005), however, suggests that the adoption of the hot spots policing 
strategy among larger police agencies during the late 1990s and early 2000s was linked to 
the extensive diffusion of innovation in computerized crime mapping and the dissemination 
of research studies documenting the potential effectiveness of preventing crime in hot spot 
areas. CompStat, a police management and accountability model that seeks to focus police 
organizations on specific problems and empower them to identify and solve those problems, 
was developed in 1994 by then Commissioner William Bratton and the New York City 
Police Department. The widespread adoption of CompStat in other police agencies can also 
be credited with growing practical interest in hot spots policing (Weisburd et al., 2001). 
Dealing with crime hot spots is now a common crime-prevention strategy engaged by many 
American police departments. 

7 

The appeal of focusing limited resources on a 
small number of high-activity crime places is 
straightforward. If we can prevent crime at hot 
spot locations, then we might be able to reduce 
total crime 

Identifying Evaluations of Hot 
Spots Policing Programs 


10 
Identifying Evaluations of Hot Spots Policing Programs 

The effectiveness of focused police efforts to prevent crime in hot spot areas was examined 
by reviewing all available academic studies evaluating hot spots policing programs. To be 
eligible for this review, programs used to control crime hot spots were limited to police 
enforcement efforts. Suitable police enforcement efforts included traditional tactics such as 
directed patrol and heightened levels of traffic enforcement, as well as alternative strategies 
such as aggressive disorder enforcement and problem-oriented policing with limited 
situational responses and limited engagement of the public. To be included in this review 
of research, eligible problem-oriented policing initiatives must engage primarily traditional 
policing tactics such as law enforcement actions, informal counseling and cautioning, and 
referrals to other agencies. Problem-oriented policing programs that involved nontraditional 
interventions implemented by other stakeholders such as community members, business 
owners, or resident managers, were not considered because of the complexities of separating 
the crime-prevention effects associated with enforcement-based responses from community-
based responses. 

Eligible program evaluations were also limited to police programs that targeted small areas 
such as street corners, homes, apartment buildings, and subway stations. Police programs 
that focused on large areas, such as an entire neighborhood, were not considered. Identified 
studies were further screened to ensure that rigorous evaluation designs, such as randomized 
experiments and quasi-experiments, were used.1 Particular attention was paid to studies that 
measured crime displacement effects and diffusion of crime-control benefit effects. Policing 
strategies focused on specific locations have been criticized as resulting in displacement 
(Repetto, 197 ); that is, criminals at targeted locations would simply move around 
the corner to areas that were not protected by focused police attention. More recently, 
academics have observed that crime-prevention programs may result in the complete 
opposite of displacementthat crime-control benefits were greater than expected and spill 
over into places beyond the target areas (Clarke and Weisburd, 1994). 

The review was not restricted to a specific period and relevant studies written in languages 
other than English were obtained and translated wherever possible. Eligible studies include 
published as well as unpublished works (journal articles, theses/dissertations, reports, books, 

1These evaluation designs permit the clearest assessments 
of cause and effect in determining whether hot spots 
policing programs prevent crime. These designs examine 
preprogram and postprogram measurements of crime 
outcomes in targeted locations relative to control 
locations. The control groups in the identified hot spots 
evaluations received routine levels of traditional police 
enforcement tactics. 


book chapters, and conference papers). See Braga (2001 and 2005) for further details of 
the systematic search methodology. A total of 97 article summaries were reviewed for any 
suggestion of an evaluation of a hot-spots policing program. Of the 97 summaries, 57 
were selected for closer review and the full-text reports, journal articles, and books for these 
evaluations were acquired and carefully assessed to determine whether the interventions 
involved focused police enforcement efforts at crime hot spots and whether the studies used 
rigorous evaluation designs. Using these methods, nine hot spots policing evaluations were 
identified and included in this review: 

1. 
Minneapolis Repeat Call Address Policing (RECAP) Program 
(Sherman, Buerger, and Gartin, 1989)
2. 
Minneapolis Hot-Spots Patrol Program (Sherman and Weisburd, 1995) 
3. 
Jersey City Drug Markets Analysis Program (DMAP) (Weisburd and Green, 1995) 
4. 
Jersey City Problem-Oriented Policing at Violent Places Project 
(Braga, Weisburd, Waring, Green Mazerolle, Spelman, and Gajewski, 1999)
5. 
St. Louis Problem-Oriented Policing (POP) in Three Drug Market Locations Study 
(Hope, 1994) 

 . Kansas City Gun Project (Sherman and Rogan, 1995a) 

7. 
Kansas City Crack House Police Raids Program (Sherman and Rogan, 1995b) 
8. 
Houston Targeted Beat Program (Caeti, 1999) 
9. 
Beenleigh (Australia) Calls for Service Project (Criminal Justice Commission, 1998) 

11 

The enforcement problem-oriented policing strategy 
resulted in significant reductions in total calls for 
service and total crime incidents, as well as varying 
reductions in all subcategories of crime types. 

Characteristics of the 
Hot-Spots Policing Programs 


14 
Characteristics of the Hot-Spots Policing Programs 

The nine evaluations were conducted in five large cities in the United States and one suburb 
in Australia. Police programs to prevent crime at hot spots fell into three broad categories: 
enforcement problem-oriented policing programs, directed and aggressive patrol programs, 
and police crackdowns and raids (Table 1). The effects of problem-oriented policing 
initiatives comprising mostly traditional tactics with limited situational responses were 
evaluated in the Minneapolis RECAP Program, Jersey City POP at Violent Places Study, 
St. Louis POP at Drug Market Locations Study, and the Beenleigh (Australia) Calls for 
Service Project. The evaluation of the Houston Targeted Beat Program examined the effects 
of three types of police strategies applied in different target areas; these strategies included 
high-visibility patrol, zero tolerance disorder policing, and enforcement problem-oriented 
policing. The Kansas City Gun Project examined the gun violence-prevention effects of 
proactive patrol and intensive enforcement of firearms laws through safety frisks during 
traffic stops, plain-view searches and seizures, and searches incident to arrests on other 
charges. The Minneapolis Hot-Spots Patrol program evaluated the effects of increased levels 
of preventive patrol on crime. The Jersey City DMAP and Kansas City Crack House Raids 
programs evaluated the effects of well-planned crackdowns on street-level drug markets and 
court-authorized raids on crack houses, respectively. 

The nine evaluations used crime-incident report data and citizen emergency calls for service 
data as official indicators of crime. Although official data are widely used for assessing trends 
and patterns of crime, these data do have shortcomings. For instance, crime-incident data 
are biased by police decisions not to record all crimes reported by citizens (Black, 1970). 
Call data are subject to both underreporting (e.g., a lack of telephones in poverty-stricken 
places) and overreporting (e.g., two separate calls reporting the same incident risk being 
counted as two distinct events; see Sherman, Gartin, and Buerger, 1989; Klinger and 
Bridges, 1997). Call data, however, are suggested to be more reliable measures of crime and 
crime-related activity than incident data or arrest data (Pierce, Spaar, and Briggs, 1988). 
Most notably, citizen calls for service are affected less heavily by police discretion than other 
official data sources (Warner and Pierce, 1993); therefore, call data are often regarded as the 
widest ongoing data collection net for criminal events in the city (Sherman, Gartin, and 
Buerger, 1989: 35). 


Table 1: Hot Spots Policing Programs. Source: Adapted from Braga (2001). 

Study 
Minneapolis (MN) RECAP 
Sherman, Buerger, and 
Gartin (1989) 

Program Elements
Problem-oriented policing to control crime at high-activity 
addresses; interventions comprised mostly traditional enforcement 
tactics with some situational responses. 

Study
Minneapolis (MN) 
Hot Spots 
Sherman and Weisburd (1995 

Program Elements
Increased uniformed police patrol in crime hot spot areas; 
treatment group, on average, experienced twice as much patrol 
presence as the control group. 

Study
Jersey City (NJ) DMAP 
Weisburd and Green (1995) 

Program Elements
Well-planned crackdowns on street-level drug markets followed by 
preventive patrol to maintain crime control gains 
Jersey City (NJ) 

Study
POP at Violent Places 
Braga et al. (1999) 

Program Elements
Problem-oriented policing to prevent crime at violent hot 
spot areas; interventions comprised mostly aggressive disorder 
enforcement tactics with some situational responses. 

Study
St. Louis (MO) 
POP in Three Drug Areas 
Hope (1994) 

Program Elements
Problem-oriented policing to prevent crime at three high-drug 
activity addresses; interventions comprised mostly traditional 
enforcement tactics with some situational responses. 

Study
Kansas City (MO) 
Crack House Raids 
Sherman and Rogan (1995a) 

Program Elements
Court-authorized raids on crack houses conducted by uniformed 
police officers. 

Study
Kansas City (MO) 
Gun Project 
Sherman and Rogan (1995b) 

Program Elements
Intensive enforcement of laws against illegally carrying concealed 
firearms in targeted beat through safety frisks during traffic stops, 
plain view, and searches incident to arrest on other charges. 

Study
Houston (TX) 
Targeted Beat Program 
Caeti (1999) 

Program Elements
Patrol initiative designed to reduce Index crimes in seven beats: 
Three beats used high visibility patrol at hot spots 
Three beats used zero tolerance policing at hot spots 
One beat used a problem-oriented policing approach that 
comprised mostly traditional tactics to control hot spots. 

Study 
Beenleigh (AUS) 
Calls for Service Project 
Criminal Justice Commission (1998) 

Program Elements
Problem-oriented policing to control crime at high-activity crime 
addresses; interventions comprised mostly traditional enforcement 
tactics with some situational responses. 

15 

The Jersey City DMAP Program found that 
well-planned crackdowns in street-level drug 
markets followed by patrol maintenance 
resulted in significant reductions in disorder 
calls for service 

Effects of Hot Spots Policing 
Programs on Crime 
and Disorder 


18 
Effects of Hot Spots Policing Programs on Crime and Disorder 

Noteworthy crime reductions were reported in seven of the nine selected studies (see Table 
2). A meta-analysis of hot spots policing experiments revealed significant overall prevention 
effects of hot spots policing programs in reducing citizen calls for service (Braga, 2005).2 
The strongest gains in crime control were reported in the Jersey City POP at Violent Places 
Study and the Kansas City Gun Project. In the Jersey City POP Study, the enforcement 
problem-oriented policing strategy resulted in significant reductions in total calls for service 
and total crime incidents, as well as varying reductions in all subcategories of crime types 
(Braga et al., 1999). Additional analyses of observation data collected over the course of the 
evaluation revealed that social disorder, such as loiterers and public drinkers, and physical 
disorder, such as trash, graffiti, and vacant lots, was also reduced significantly. Proactive 
patrols focused on firearm recoveries in the Kansas City Gun Project resulted in a 5 
percent increase in gun seizures and a 49 percent decrease in gun crimes in the target beat 
area; gun seizures and gun crimes in the comparison beat area did not change significantly 
(Sherman and Rogan 1995a). A separate study examined community reaction to the Kansas 
City intervention and found that the community strongly supported the intensive patrols 
and perceived an improvement in the quality of life in the treatment neighborhood (Shaw, 
1995). 

The Minneapolis Hot Spots Patrol Program revealed that roughly doubling the level of 
patrol in crime hot spots resulted in modest, but significant, reductions in total calls for 
service, ranging from percent to 13 percent (Sherman and Weisburd, 1995). Moreover, 
systematic observations of the hot spots documented that disorderly behavior in the targeted 
areas was also reduced (Sherman and Weisburd, 1995). The Jersey City DMAP Program 
found that well-planned crackdowns in street-level drug markets followed by patrol 
maintenance resulted in significant reductions in disorder calls for service (Weisburd and 
Green, 1995). Similarly, the St. Louis POP quasi-experiment found that the enforcement 
problem-oriented policing strategy was associated with varying degrees of reductions in total 
calls for service at all three high-activity drug locations; these reductions were greater than 
any reductions observed in other blocks and intersections in the surrounding areas (Hope, 
1994). The Kansas City Crack House Raid experiment reported modest decreases in citizen 
calls for service and crime offenses at the targeted blocks that decayed within 2 weeks of the 
raids (Sherman and Rogan, 1995b). 

2Meta-analysis is a technique used to investigate overall 
program effects associated with a selected set of studies 
(see Lipsey and Wilson, 2001). 


The Houston Targeted Beat Program suggests that the aggregated target beats experienced 
significant reductions in auto theft, total Part I index crimes, and total Part I patrol 
suppressible crimes (robbery, burglary, and auto theft) (Caeti, 1999). The targeted beats 
where zero tolerance aggressive disorder policing was used to control hot spots experienced 
mixed reductions in Part I crimes; the three targeted beats where high-visibility directed 
patrol was used to control hot spots experienced reductions in a wide variety of Part I 
crimes; the one targeted beat where an enforcement problem-oriented policing strategy was 
implemented to control hot spots did not experience noteworthy decreases. The limits of 
the analytic framework used in this evaluation preclude conclusions that certain types of 
policing strategies may be more effective in preventing crime in hot spots (see Braga, 2001). 
Nevertheless, the results of this study can be broadly taken to support the position that 
focused police enforcement efforts can be effective in reducing crime at hot spots. 

The evaluation of the Beenleigh Calls for Service Project found no noteworthy differences 
in the total number of calls in the town of Beenleigh relative to the matched town of 
Brown Plains (Criminal Justice Commission, 1998); however, simple comparisons found 
noteworthy reductions in total citizen calls for service in 1 of 19 case studies included in 
the report. The research team concluded that the problem-oriented policing strategy enjoyed 
some success in reducing calls for service at the targeted locations, but because of the small 
scale of the project and limitations of the research design, these crime-prevention gains were 
not large enough to be detected at the aggregate town level (Criminal Justice Commission, 
1998). 

The Minneapolis RECAP evaluation revealed no significant differences in the prevalence of 
citizen calls for service at addresses that received the problem-oriented policing treatment 
(Sherman, Buerger, and Gartin, 1989). These results were probably caused by methodological 
problems in the research design, such as the assignment of too many cases to the RECAP unit, 
thereby outstripping the amount of resources and attention the police officers provided to 
each address (Buerger, 1993). Although the overall findings suggest that the RECAP program 
was not effective in preventing crime, a case study analysis revealed that several addresses 
experienced dramatic reductions in total calls for service (Buerger, 1992). 

19 

Table 2: Results of Hot Spots Policing Evaluations. Source:Adapted from Braga (2001). 

20 

Study 
Minneapolis (MN) RECAP 
Sherman, Buerger, and 
Gartin (1989) 

Crime Outcomes
No effect. 

Other Outcomes
None. 

Displacement/Diffusion
Not measured.

Study  
Minneapolis (MN) 
Hot Spots 
Sherman and Weisburd (1995 

Crime Outcomes
Reductions in total citizen 
calls for service. 

Other Outcomes
Observational data 
revealed reductions 
in crime and disorder. 

Displacement/Diffusion
Not measured. 

Study
Jersey City (NJ) DMAP 
Weisburd and Green (1995) 

Crime Outcomes
Reductions in citizen calls 
for disorder offenses. 

Other Outcomes
None. 

Displacement/Diffusion
Little evidence of 
displacement; analyses 
suggest modest diffusion 
of crime-control benefits. 

Study
Jersey City (NJ) 
POP at Violent Places 
Braga et al. (1999) 

Crime Outcomes
Reductions in total calls 
for service and total crime 
incidents.All subcategories 
of crime experienced 
varying reductions. 

Other Outcomes
Observational data 
revealed reductions 
in social and physical 
disorder. 

Displacement/Diffusion
Little evidence of 
immediate spatial 
displacement. Possible 
diffusion of crime-control 
benefits. 

Study
St. Louis (MO) 
POP in Three Drug Areas 
Hope (1994) 

Crime Outcomes
All three drug locations 
experienced varying 
reductions in total calls. 

Other outcomes
None. 

Displacement/Diffusion
One location experienced 
significant displacement. 

Study
Kansas City (MO) 
Crack House Raids 
Sherman and Rogan (1995a) 

Crime Outcomes
Modest decreases in citizen 
calls and offense reports that 
decayed in 2 weeks 

Other Outcomes
None. 

Displacement/Diffusion
Not measured. 

Study
Kansas City (MO) 
Gun Project 
Sherman and Rogan (1995b) 

Crime Outcomes
Increase in number of 
guns seized by the police 
followed by decrease in gun 
crimes. 

Other Outcomes
Community survey 
revealed favorable 
opinion of police 
efforts. 

Displacement/Diffusion
No significant crime 
displacement. 
Diffusion effects reported. 

Study
Houston (TX) 
Targeted Beat Program 
Caeti (1999) 

Crime Outcomes
Aggregated targeted beats 
experienced significant crime 
reductions. Specific beats 
reported mixed results. 

Other Outcomes
None. 

Displacement/Diffusion
No evidence of 
displacement. 
Diffusion effects reported 

Study
Beenleigh (AUS) 
Calls for Service Project 
Criminal Justice Commission 
(1998) 

Crime Outcomes
No noteworthy differences 
in total number of calls 
between Beenleigh and 
Brown Plains areas. 
Noteworthy reductions in 
calls reported in majority of 
case studies. 

Other Outcomes
None. 

Displacement/Diffusion
Not measured. 

Displacement and Diffusion Effects 

Five studies examined whether focused police efforts were associated with crime displacement 
or diffusion of crime-control benefits (see Table 2). Prior to a discussion of the research 
findings, it must be noted that it is very difficult to detect displacement effects because the 
potential manifestations of displacement are quite diverse. As Barr and Pease (1990) suggest, 
if, in truth, displacement is complete, some displaced crime will fall outside the areas and 
types of crime being studied or be so dispersed as to be masked by background variation 
no research study, however massive, is likely to resolve the issue. Diffusion effects are likely 
to be as difficult to assess. All five studies were limited to examining immediate spatial 
displacement and diffusion effects; that is, whether focused police efforts in targeted areas 
resulted in crime moving around the corner or whether these surrounding areas experienced 
unintended crime-control benefits. 

None of the five studies reported substantial immediate spatial displacement of crime 
into areas surrounding the targeted locations. Four studies suggested possible diffusion 
effects associated with the focused police interventions. The Jersey City POP at Violent 
Places experiment found little evidence of displacement in surrounding areas and reported 
significant decreases in total calls for service and disorder calls for service in surrounding 
areas. The Jersey City DMAP evaluation found significant decreases in public morals3 calls for 
service and narcotics calls for service in areas immediately surrounding the targeted drug hot 
spots. The Kansas City Gun Project evaluation examined whether gun crimes were displaced 
into seven beats contiguous to the target beat. None of the contiguous beats showed 
significant increases in gun crime and two of the contiguous beats reported significant 
decreases in gun crimes. 

The Houston Targeted Beat quasi-experiment also examined displacement and diffusion 
effects by analyzing reported Part I index crimes in beats contiguous to the targeted beats. 
The analyses revealed no overall evidence of displacement and contiguous beats surrounding 
three targeted beats (one problem-oriented policing beat and two zero-tolerance beats) 
experienced possible diffusion effects as several types of reported Index crimes decreased 
notably. The St. Louis POP at Drug Locations quasi-experiment assessed displacement effects 
by comparing trends in calls for service at targeted addresses to nontargeted addresses on 

21 
3Public morals calls for service represented a 
subcategory of disorder calls for service in the 
Jersey City DMAP evaluation. According to 
Weisburd and Green (1995), public morals calls 
for service included citizen reports of gambling, 
lewdness, possession of liquor, and prostitution. 


22 
the same block. Significant increases in calls for service at nontargeted addresses on the same 
block were reported in only one of the three analyses. The primary cause of the observed 
displacement was a shift in drug sales from a targeted apartment building to a similar 
nontargeted apartment building on the same block. 


The results of this systematic review support 
the assertion that focusing police efforts on 
high-activity crime places can be used to 
good effect in preventing crime. 

Conclusion and Policy 
Implications 


24 
Conclusion and Policy Implications 

The results of this systematic review support the assertion that focusing police efforts on 
high-activity crime places can be used to good effect in preventing crime. Seven of the nine 
evaluations reported noteworthy reductions in crime and disorder. Problems in the research 
and evaluation design probably accounted for the lack of crime-prevention gains in the 
Minneapolis RECAP experiment. This review also supports the growing body of research 
evidence that suggests that focused crime-prevention efforts do not inevitably lead to the 
displacement of crime problems (Clarke and Weisburd 1994; Hesseling 1994; Eck 1993); 
rather, when displacement was measured, it was quite limited and often unintended crime-
prevention benefits were associated with the hot spots policing programs. While only five 
studies examined potential displacement and diffusion effects, none of these evaluations 
reported substantial immediate spatial displacement of crime into areas surrounding the 
targeted locations. The National Research Councils Committee to Review Research on 
Police Policy and Practices examined the results of an earlier and more detailed version of 
this review (Braga, 2001) and concluded that there was strong empirical support for the 
hot spots policing approach to crime prevention (Skogan and Frydl, 2004: 240). 

While the available evidence supports the assertion that hot spots policing is effective, 
there are important gaps in our knowledge about it. Clearly, the enforcement-oriented 
strategies reviewed here work in preventing crime. We do not know, however, which 
enforcement strategies are more effective in preventing crime and under what circumstances 
certain strategies are more appropriate. For instance, we do not know whether many of 
the observed crime-control gains were generated by increased arrests, increased contacts 
with potential offenders, or simply increased police presence in very small areas. This 
small body of evaluation research also does not unravel the important question of whether 
enforcement-oriented programs result in long-term crime reductions in hot spot areas. 
Comparison periods to detect potential crime-prevention effects ranged from only 1 month 
(Sherman and Rogan, 1995b) to 1 year (Sherman and Weisburd, 1995). 

This review also offers little insight into the effectiveness of enforcement tactics relative to 
other broader-based community problem-solving policing programs (Skogan and Hartnett, 
1997). Research suggests that a variety of situational factors causes crime to cluster at 


particular places (Eck and Weisburd, 1995). Proactive patrols, raids, and crackdowns 
specifically do not address the site features (such as easy access, lack of capable guardians, 
inept or improper place management, and the presence of value items) and facilities (such 
as the presence of abandoned buildings and bars) that cause specific locations to generate 
high volumes of crime. With the exception of the problem-oriented policing programs with 
limited situational interventions, the place-oriented interventions in this review consisted 
of uniform tactics applied across varied places. Perhaps a greater focus on changing the 
conditions that cause crime to cluster might result in longer lasting crime reductions in hot 
spot areas. 

The recent National Research Council review of police policy and practices also suggests that 
the most generalized strategiesfor example, preventive patrol and drug raidsare likely to 
have less impact than approaches that include more focused problem-solving elements, such 
as working with landlords, local business owners, and residents (Skogan and Frydl, 2004). 
Our understanding of the effects of hot spots policing, however, remains very general. If we 
are to maximize the crime-prevention effects of hot spots approaches we need to examine 
carefully the interaction of different strategies with different hot spots settings. This effort 
would demand a large group of studies, but given the promise of hot spots policing, such 
an investment in research in this area seems appropriate. Future studies should examine the 
monetary costs associated with implementing these programs. In the studies reviewed here, 
very little attention was paid to issues such as staffing, overtime costs, and other related 
expenditures.4 

Also, too little attention has been paid to the potential harmful effects of hot spots 
approaches. Police effectiveness studies traditionally have overlooked the effects of policing 
practices on citizen perceptions of police legitimacy (Tyler, 2000; Tyler, 2001). Does the 
concentration of police enforcement in specific hot spots lead citizens to question the 
fairness of police practices? There is some evidence that residents of areas that are subject 
to hot spots policing welcome the concentration of police efforts in problem places (Shaw, 
1995); however, focused aggressive police enforcement strategies have been criticized as 
resulting in increased citizen complaints about police misconduct and abuse of force in New 
York City (Greene, 1999). Citizen appraisals of police legitimacy are greatly influenced by 
whether community members perceive that they were treated fairly and with respect and 

25 
4For instance, in the Kansas City Gun Study, the 
evaluators note that the intervention was funded 
by a U.S. Bureau of Justice Assistance Weed and 
Seed grant to the Kansas City (Missouri) Police 
Department (Sherman and Rogan, 1995a). While 
the evaluation notes that the program budget paid for 
police overtime and extra patrol cars in the targeted 
areas, there is no discussion of specific dollar amounts 
or the cost-effectiveness of the approach. 


2 
dignity by police officers (Tyler, 2000; Tyler, 2001). As in the case of understanding the 
effectiveness of police strategies, the potential effects of hot spots policing on legitimacy 
may depend in good part on the types of strategies used and the context of the hot 
spots affected. But whatever the effects, we need to know more about the effects of hot 
spots policing approaches on the communities that the police serve. Police executives 
considering enforcement-oriented hot spots policing initiatives should engage the 
community in the development of the program and train officers in fair and respectful 
policing techniques. 

Finally, the research overall strongly supports the position that hot spots policing can 
have a meaningful effect on crime without simply displacing crime-control benefits to 
areas nearby. However, a recent study, which reinforces the findings that there is little 
immediate spatial displacement of crime as a result of hot spots policing approaches, 
identifies other displacement outcomes that may occur in focused policing efforts 
(Weisburd et al., 200 ). Offenders interviewed in the study described factors that 
inhibited spatial displacement, including the importance of familiar territory to 
offenders and the social organization of illicit activities at hot spots that often precluded 
easy movement to other areas that offer opportunities for crime. Prostitutes, for example, 
were found to work near their homes, and described being uncomfortable in moving 
to other areas where different kinds of people worked and different kinds of clients 
were found. Prostitutes and drug dealers in the study described the importance of 
the familiarity of a place to their clients, and some offenders talked of the dangers of 
encroaching on the territories of offenders in other hot spots. 

Overall, a number of factors seemed to discourage spatial displacement in the study. 
Nonetheless, Weisburd et al. (200 ) find that offenders will often try other modes 
of adaptation to police interventions, the most common being a change in methods 
of committing illegal acts. Prostitutes and drug dealers, for example, may begin to 
make appointments with their customers, or move their activities indoors to avoid 
heightened police activities on the street. While the net gain in crime prevention may 
still be large for hot spots efforts, these findings suggest the importance of continued 
investigation of possible nonspatial displacement (e.g., method displacement) outcomes 
in hot spots policing. 


References


28 
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