Adam J. McKee, Ph.D.
Section 3.3: Police and Crime
Police and Crime
The article below was written by Lawrence W. Sherman for the National Institute of Justice.
Policing for Crime Prevention
The more police we have, the less crime there will be. While citizens and public officials often espouse that view, social scientists often claim the opposite extreme: that police make only minimal contributions to crime prevention in the context of far more powerful social institutions, like the family and labor markets. The truth appears to lie in between. Whether additional police prevent crime may depend on how well they are focused on specific objectives, tasks, places, times and people. Most of all, it may depend upon putting police where serious crime is concentrated, at the times it is most likely to occur: policing focused on risk factors.
The connection of policing to risk factors is the most powerful conclusion reached from three decades of research. Hiring more police to provide rapid 911 responses, unfocused random patrol, and reactive arrests does not prevent serious crime. Community policing without a clear focus on crime risk factors generally shows no effect on crime. But directed patrols, proactive arrests and problem-solving at high-crime “hot spots” has shown substantial evidence of crime prevention. Police can prevent robbery, disorder, gun violence, drunk driving and domestic violence, but only by using certain methods under certain conditions.
These conclusions are based largely on research supported by the National Institute of Justice, the research arm of the Office of Justice Programs in the U.S. Department of Justice. In recent years, increasing numbers of police executives have incorporated these findings into their crime prevention strategies. University of Wisconsin law professor Herman Goldstein’s (1979) paradigm of “problem-oriented policing” directed research attention to the specific things police do, and how they can focus their resources to attack the proximate causes of public safety problems. The Justice Department’s adoption of this perspective has yielded an increasingly complex but useful body of knowledge about how policing affects crime.
One of the most striking recent findings is the extent to which the police themselves create a risk factor for crime simply by using bad manners. Modest but consistent scientific evidence supports the hypothesis that the less respectful police are towards suspects and citizens generally, the less people will comply with the law. Changing police “style” may thus be as important as focusing police “substance.” Making both the style and substance of police practices more “legitimate” in the eyes of the public, particularly high-risk juveniles, may be one of the most effective long-term police strategies for crime prevention.
This chapter begins with a review of the eight major hypotheses about how the police can prevent crime. It then describes the varying strength of the scientific evidence on those hypotheses, in relation to the “rigor” of the scientific methods used to test them. The available studies are summarized for both their conclusions and their scientific rigor. The chapter then attempts to simplify these results by answering the questions about what works, what doesn’t, and what’s promising. Major gaps in our knowledge are also examined. The chapter concludes with recommendations derived from these findings for future federal investment in both evaluation research and police methods to be developed for evaluation.
Eight Major Hypotheses About Policing and Crime
Other things being equal,
- Numbers of Police. The more police a city employs, the less crime it will have.
- Rapid Response to 911. The shorter the police travel time from assignment to arrival at a crime scene, the less crime there will be.
- Random Patrols. The more random patrol a city receives, the more a perceived “omnipresence” of the police will deter crime in public places.
- Directed Patrols. The more precisely patrol presence is concentrated at the “hot spots” and “hot times” of criminal activity, the less crime there will be in those places and times.
- Reactive Arrests. The more arrests police make in response to reported or observed offenses of any kind, the less crime there will be.
- Proactive Arrests. The higher the police-initiated arrest rate for high-risk offenders and offenses, the lower the rates of serious violent crime.
- Community Policing. The more quantity and better quality of contacts between police and citizens, the less crime.
- Problem-Oriented Policing. The more police can identify and minimize proximate causes of specific patterns of crime, the less crime there will be.
Varieties of Police Crime Prevention
Numbers of Police. Like the deterrence hypothesis itself, the claim that police prevent crime is not a “theory” in a truly scientific sense. The idea was developed not as a mathematical equation but as a general “doctrine” of public policy in the heat of democratic debate. The doctrine was based not just on speculation, but also on the apparent results of several “demonstration projects” with some empirical results. These included the court supervised “Bow Street Runners” and the privately operated but publicly chartered Thames River “Marine Police.” As the level of violence throughout the 19th century declined while the number of police increased, many observers concluded that the more police, the less crime.
Rapid Response to 911. The general form of this claim is that the shorter the police travel time from assignment to arrival at a crime scene, the more likely it is that police can arrest offenders before they flee. This claim is then extended to rapid response producing three crime prevention effects. One is a reduction in harm from crimes interrupted in progress by police intervention. Another, more general benefit of rapid response time is a greater deterrent effect from the threat of punishment reinforced by response-related arrests. The third hypothesized prevention effect comes from the incapacitation through imprisonment of offenders prosecuted more effectively with evidence from response-related arrests. All of these claims presume, of course, that police are notified during or immediately after the occurrence of a crime. This premise, like the hypotheses themselves, is empirically testable, and it’s falsification could logically falsify the hypotheses built upon the assumption of its validity.
Random Patrols. Early beat officers were directed to check in at specific places at specific times, with rigid supervision of the prescribed patrol patterns. The increasing emphasis on rapid 911 response in automobiles gradually put an end to directed patrols, allowing officers to patrol at random far beyond their assigned beats. This policy was justified by the theory that unpredictability in patrol patterns would create a perceived “omnipresence” of the police that deters crime in public places. Chicago Police Chief and Berkeley Criminology Dean Orlando W. Wilson was a widely cited proponent of this view. Although he favored the use of police workload analysis to determine how many officers should be assigned to different beats and shifts, modern police practice shows little variation in patrol presence by time and place. Nonetheless, many police chiefs and mayors claim that hiring more officers to patrol in this fashion would reduce crime.
Directed Patrols. Since the advent of computerized crime analysis, however, a far greater precision in the identification of crime patterns has become possible. Police have used that precision to focus patrol resources on the times and places with the highest risks of serious crime. The hypothesis is that the more patrol presence is concentrated at the “hot spots” and “hot times” of criminal activity, the less crime there will be in those places and times. The epidemiological underpinning for this claim is NIJ-funded research showing that the risk of crime is extremely localized, even within high crime neighborhoods, varying widely from one address to another.
Reactive Arrests. Like police patrol, arrest practices can be either unfocused or focused on crime-risk factors. Reactive arrests (in response to specific citizen complaints) are like random patrol in that they cast a wide net, warning all citizens that they can be arrested for all law violations at all times. This net is necessarily quite thin. Observations of thousands of police encounters with criminal suspects shows that police choose not to arrest suspects in the majority of the cases in which there was legal basis to do so. The frequent decision not to arrest has been noticed by crime victims’ advocacy groups, who argue that more arrests will produce less crime. This hypothesis, like deterrence generally, is expressed at two levels of analysis: the “general” or community-wide, and the “specific” or individual-level. The individual-level hypothesis has been questioned for decades by social scientists, and even some police, who suggest exactly the opposite: that arrest, especially for minor offenses (which are by far the most common), provokes a response by offenders making them more likely to commit future crime than if they had not been arrested.
Proactive Arrests. Like directed patrol, proactive (police-initiated) arrests concentrate police resources on a narrow set of high-risk targets. The hypothesis is that a high certainty of arrest for a narrowly defined set of offenses or offenders will accomplish more than low arrest certainty for a broad range of targets. In recent years the theory has been tested with investigations of four primary high risk targets: chronic serious offenders, potential robbery suspects, drug market places and areas, and high-risk places and times for drunk driving. All but the first can be tested by examining the crime rate. The hypothesis about chronic serious offenders is tested by examining the rate at which such offenders are incapacitated by imprisonment from further offending.
Another version of the proactive arrest hypothesis is called “zero tolerance,” based on the “broken windows” theory. The theory is that areas appearing disorderly and out-of-control provide an attractive climate for violent crime–just as a window with one broken pane attracts more stones than a completely unbroken window. The crime prevention hypothesis is that the more arrests police make for even petty disorder), the less serious crime there will be.
Community vs. Problem-Oriented Policing
The hypotheses about community- and problem-oriented-policing are less focused than the others, so much so that some observers have even advised against trying to test them. They both involve far more variations and possible combinations of police activities than the narrow deterrence hypotheses. Community and problem-oriented policing are put into practice more like a “stew” of different elements than a single type of “food.” Yet it is just this flexibility that proponents hypothesize to give them their power. Crime problems vary so widely in nature and cause that effective policing for prevention must vary accordingly, and arguably require many elements to succeed.
While community and problem-oriented policing are often said to be overlapping strategies, they actually have very different historical and theoretical roots. Community policing arises from the crisis of legitimacy after the urban race riots of the 1960s, the proximate causes of which several blue-ribbon reports blamed on police (President’s Commission on Law Enforcement and Administration of Justice, 1967; National Advisory Commission on Civil Disorders, 1968). The reports claimed police had lost contact with minority group residents, both by changing from foot patrols to radio cars and by taking a more legalistic approach to law enforcement. In various ways, most notably “team policing”, the police were urged to increase their contact with citizens in more positive settings than just responding to emergencies. Thus for almost three decades the Community Policing hypothesis has been that increasing the quantity and quality of police-citizen contact reduces crime.
Problem-oriented policing, in contrast, arose from the crisis of police effectiveness at crime prevention provoked in the 1970s by some of the very studies reviewed in this chapter. As one of its early sponsors, Gary Hayes, put it, the studies told police chiefs that nothing they were doing–putting more police on the street into random patrols, rapid responses–was working to fight crime. The strategy of problem-oriented policing conceived by Professor Goldstein provided a new paradigm in which to focus innovation, regardless of any contact with the citizenry. Where the core concept of community policing was community involvement for its own sake, the core concept for problem-oriented policing was results: the effect of police activity on public safety, including (but not limited to) crime prevention. Nonetheless, community policing has also been justified by its hypothesized effects on crime, not the least of which has been the rationale for the 100,000 federally funded police officers.
Community Policing. The crime prevention effects of community policing are hypothesized to occur in four major ways.
- Neighborhood Watch. This hypothesis justifies one of the most widespread community policing programs, “block watch”: increasing volunteer surveillance of residential neighborhoods by residents, which should deter crime because offenders know the neighbors are watching.
- Community-Based Intelligence. This hypothesis justifies the many community meetings and informal contacts police sought through storefront offices, foot patrol and other methods: increasing the flow of intelligence from citizens to police about offenses and offenders, which then increases the probability of arrest for crime and the deterrent incapacitative effects of arrest. The increased flow of citizen intelligence can also increase police effectiveness at crime prevention through problem-solving strategies.
- Public Information About Crime. This hypothesis is just the reverse of the last one: increased flow of police intelligence about crime back to citizens improves citizen ability to protect themselves, especially in light of recent changes in crime patterns and risks. The latest version of this idea is “reverse 911,” under which police fax out warnings of criminal activity to a list of residential and business fax numbers requesting the service.
- Police Legitimacy. Given the historical roots of community policing, perhaps the most theoretically compelling version of its crime prevention hypothesis addresses police legitimacy, or public confidence in the police as fair and equitable. Recent theoretical and basic research work in “procedural justice” provides a more scientifically elaborate version of this hypothesis than its proponents in the 1960s intended. The claim is not just that police must be viewed as legitimate in order to win public cooperation with law enforcement. The claim is that a legitimate police institution fosters more widespread obedience of the law itself. Gorer even attributes the low levels of violent crime in England to the example of law-abiding masculinity set by 19th Century police, a role model that became incorporated into the “English character.” There is even evidence that the police themselves become less likely to obey the law after they have become disillusioned with its apparent lack of procedural justice.
Problem-Oriented Policing offers infinite specific hypotheses about crime prevention, all under this umbrella claim: the more accurately police can identify and minimize proximate causes of specific patterns of crime, the less crime there will be. In recent years this claim has taken two major forms:
- Criminogenic Commodities. The more police can remove criminogenic substances from the micro-environments of criminal events, the fewer crimes there will be. This claim arises from the growing emphasis on the causation of criminal events as partly independent of the causation of individual criminality. Like the theories about preventing crime in places, the premise is that many crimes require certain preconditions, such as guns or cash or moveable property.
- Converging Offenders and Victims. Another precondition of violent criminal events is that victims and offenders must intersect in time and space. A major problem-solving theory of crime prevention is to keep the more basic elements of criminal events from combining: the more police can reduce the intersection of motivated offenders in time and space with suitable targets of crime, the less crime there will be.
For all of its scientific limitations, the evidence shows substantial consistency on a number of the hypotheses, and some tentative conclusions on others. All science, of course, is provisional, with better research designs or theories revealing previously undiscovered patterns. It is no small achievement that police crime prevention research has developed to the point of having reached some conclusions to discard.
The available evidence supports two major conclusions about policing for crime prevention. One is that the effects of police on crime are complex, and often surprising. The other is that the more focused the police strategy, the more likely it is to prevent crime. The first conclusion follows from the findings that arrests can sometimes increase crime, that traffic enforcement may reduce robbery and gun crime, that the optimal deterrent effect of a police patrol may be produced by 15 minutes of presence in a hot spot, and that prevention effects generally fade over time without modification and renewal of police practices. The second conclusion follows from the likely failure to achieve crime prevention merely by adding more police or shortening response time across the board.
The substantial array of police strategies and tactics for crime prevention (Reiss, 1995) has a small but growing evaluation literature. Using the standard of at least two consistent findings from level 3 scientific methods score (well-measured, before-after studies with a comparison group) and a preponderance of the other evidence in support of the same conclusion, the research shows several practices to be supported by strong evidence of effectiveness, and several with strong evidence of ineffectiveness.
- increased directed patrols in street-corner hot spots of crime
- proactive arrests of serious repeat offenders
- proactive drunk driving arrests
- arrests of employed suspects for domestic assault
- neighborhood block watch
- arrests of some juveniles for minor offenses
- arrests of unemployed suspects for domestic assault
- drug market arrests
- community policing with no clear crime-risk factor focus
Several other strategies fail to meet the test of strong evidence for generalizable effectiveness, but merit much more research and development because of encouraging findings in the initial research.
- police traffic enforcement patrols against illegally carried handguns
- community policing with community participation in priority setting
- community policing focused on improving police legitimacy
- zero tolerance of disorder, if legitimacy issues can be addressed
- problem-oriented policing generally
- adding extra police to cities, regardless of assignments
- warrants for arrest of suspect absent when police respond to domestic violence
What is notably absent from these findings, however, are many topics of great concern to police. Gang prevention, for example, is a matter about which we could not find a single impact evaluation of police practices. Police curfews and truancy programs lack rigorous tests. Police recreation activities with juveniles, such as Police Athletic Leagues, also remain unevaluated. Automated identification systems, in-car computer terminals, and a host of other new technologies costing billions of dollars remain unevaluated for their impact on crime prevention. There is clearly a great deal of room for further testing of hypotheses not listed here due to the absence of available scientific evidence.
Source: NIJ. Preventing Crime: What Works, What Doesn’t, What’s Promising.
Modification History File Created: 08/10/2019 Last Modified: 08/13/2019
This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.