Random preventive patrol strategies are based on the idea that visible police presence in an area provides a general deterrent effect on crime and that, subsequently, the general public's fear of crime is reduced by that same police presence. It would be expected, as a result, that crimes that would normally take place in fairly public areas, such as general property offenses or street crimes, would be more significantly impacted by preventive patrolling practices, whereas offenses typically committed in relative seclusion would be less susceptible to the deterrence effects of preventive patrolling. The utilization of police resources for random preventive patrol activities is, however, ineffective at deterring crime and apprehending offenders. Research suggests that targeted preventive activities in strategic zones where the majority of crimes occur, or when treatments driven by specific policies or practices aimed at meeting strategically defined goals are utilized, is far more effective in reducing crime (Sherman and Weisburd, 1995).
The first study that aimed to discern the effectiveness of preventive patrolling practices took place in Kansas City, Missouri in 1972-1973. The Kansas City Preventive Patrol Experiment took place within fifteen beats, and each beat was assigned to a proactive group where preventive patrols were increased, a control group where no changes were made to preventive patrolling practices, or a reactive group where preventive patrolling was suspended (Kelling et Al., 1974). Generalized, the findings of the Kansas City Experiment showed no significant impact on crime deterrence, citizen fear of crime, community attitudes toward the police, or police response time (Kelling et Al., 1974).
The Kansas City Experiment suffered from a number of errors in methodology, as outlined by Larson (1975), but also provided a number of interesting facts surrounding patrol deployment and perceived police presence as an unintended by-product. It is important to first note the most applicable shortcomings identified in the Kansas City Experiment in order to understand why the general finding that preventive patrol activities appeared to have no significant impact cannot be taken at face value. Perhaps most importantly, the areas designated as reactive beats still received a significant visible police presence through responses to service calls, the routine operations of specialized units, and patrol-initiated activities such as building or car checks and stopping motorists for traffic violations (Larson, 1975). Further, as a result of using multiple patrol units dispatched in response to calls for service in the reactive groups, and coupled with an increased use of emergency lights and sirens, there was no diminished public awareness of a police presence in these areas (Larson, 1975). In essence, according to Larson (1975), the nature and design of the Kansas City Experiment served to empirically test whether patrol units could be spatially redistributed within a confined region or zone without an actual or perceived degradation in service, instead of actually testing whether preventive patrol practices were effective. Understanding the shortcomings of the Kansas City Experiment results in a clearer understanding of why the conclusion that routine preventive patrol activities has little or no value is not justifiable. In fact, Larson's (1975) analysis of the experiment provides the framework for understanding Sherman and Weisburd's (1995) hypothesis that patrol dosage in the Kansas City Experiment actually varied by a statistically insignificant amount from normal patrol levels, which is why the Kansas City Experiment seemingly provided support for the concept that preventive patrol has no effect even though other studies provided contradictory evidence and conclusions. It is through targeted patrol dosage in specific zones, or hot spots, and through the use of strategically defined objectives during patrol activities, that the effectiveness of certain types of preventive patrol efforts becomes identifiable.
Sherman and Weisburd (1995), McGarrell et Al. (2001), and Braga (2001) all provide insights into the effects of “hot spot” policing, which is a form of place-oriented preventive patrol. McGarrell et Al. (2001) also examined the effects of providing a clear strategic goal for officers during preventive patrol activities, namely the locating and seizure of illegally possessed firearms, and its subsequent effect on crime. These studies provide the basis for the conclusion that certain preventive patrol practices are effective under certain circumstances and random preventive patrol activities are ineffective, even though the conclusions of the aforementioned Kansas City Experiment dominated police thinking about patrol strategies for more than two decades (Sherman and Weisburd, 1995).Sherman and Weisburd (1995) tested the effects of intensified, but intermittent, patrol on identified “hot spots” of criminal activity in Minneapolis, Minnesota. In the study, one hundred and ten locales were identified and split into two even groups, with the experimental group receiving substantially increased levels of patrol dosage as opposed to the control group. It is worth noting that the experiment was designed only to measure the effect of heightened police presence at these locations, and that the activities of officers during the time they were within each zone was not restricted; in fact, the observed activities of officers during the time spent within the boundaries of the hot spot included activities unrelated to patrol, such as reading, sunning, and general conversation (Sherman and Weisburd, 1995). The study found clear, albeit modest, general deterrence effects as a result of increased police presence in the targeted areas, though with two caveats: first, there was no test of whether criminal activity was merely displaced to other areas so general deterrence effects throughout the community can not be claimed, and second, the experiment had not been replicated and therefore may be limited in external validity thus far (Sherman and Weisburd, 1995).
Along a similar line of inquiry, McGarrell et Al. (2001) evaluated the effect of directed patrol efforts, wherein police units were freed from the responsibility of responding to calls for service and were instructed to proactively patrol their assigned neighborhood with an emphasis on locating and seizing illegally owned firearms. Two different methodologies were utilized in order to examine the effects of a general deterrence approach versus a specific deterrence approach: in target area one, police were instructed to increase traffic stops to maximum levels in order to create a sense of significantly increased police presence, testing a general deterrence strategy that was also anticipated to lead to seizures of illegal weapons and drugs; in target area two, police were instructed to focus on investigating suspicious persons, a specific deterrence strategy, and conducting more thorough investigations for illegal weapons and drugs with each suspicious person (McGarrell et Al., 2001). Interestingly, the results of the study show a significant reduction in firearms related crimes in the specific deterrence beat, but actually show an increase in the general deterrence beat (McGarrell et Al., 2001). One possible explanation provided by McGarrell et Al. (2001) for the success of the targeted offender/specific deterrence approach lies in the possible interpretation of police actions within that zone, as a result of proactive, directed preventive patrol efforts, as heightened surveillance as well as removing firearms from those potential offenders most likely to use them. In effect, a directed strategy for preventive patrol activities in higher crime locations yields a significant impact in the reduction of violent crimes.
Perhaps the most compelling evidence for the effectiveness of place-oriented preventive patrol as opposed to random preventive patrol comes from Braga’s (2001) analysis and systematic review of “hot spot” policing studies. Out of nine studies, seven showed noteworthy crime reductions as a result of place-oriented patrol activities, and it should be noted that intervention types ranged among three broad categories: enforcement problem-oriented-policing (POP) interventions, directed and aggressive patrol programs, and the use of crackdowns and raids (Braga, 2001). It is also important to note that methodological problems in the research and evaluation designs of two studies most likely accounts for the lack of observed reduced criminal activity in said studies, and the remaining study showing no discernable impact on reducing crime suffered from issues in implementation that could account for a lack of significance in results (Braga, 2001). Overall, Braga’s (2001) review contributes to a growing body of research evidence supporting the conclusion that targeting “hot spots” of crime with focused, strategic intervention efforts is effective at reducing crime, both at the targeted zone and in surrounding areas, and is far more effective than random preventive patrol activities. These findings also provide positive indications that displacement of crime from a targeted zone to a less actively patrolled zone may be unfounded, though only five of the studies in Braga’s (2001) review measured the potential displacement of criminal activity.
Given the briefly summarized results of the aforementioned experiments and systematic reviews, it is difficult to justify random preventive patrol efforts in light of far more effective results from directed patrol activities in the reduction of crime. Theoretically, random preventive patrol activities should provide general deterrence effects for publicly visible crimes, such as vandalism, disorderly conduct, robberies and burglaries, and potentially aggravated assault. However, targeted patrol activities appear to have the same effect with regards to increased public visibility in providing a level of general deterrence while simultaneously providing far more effective specific deterrence effects, as noted in the studies and reviews above. Therefore, the effectiveness of random preventive patrol activities is conclusively inefficient when compared with other methods of targeting and reducing criminal activity within any given zone.
Anthony Braga (2001). “The Effects Of Hot Spots Policing On Crime,” The Annals of The American Society of Science, pp. 104-125.
Richard C. Larson (1975). “What Happened to Patrol Operations in Kansas City? A Review of the Kansas City Preventive Patrol Experiment” Journal of Criminal Justice, 3:267-297.
Edmund McGarrell, Steven Chermak, Alexander Weiss, and Jeremy Wilson (2001) “Reducing Firearms Violence Through Directed Police Patrol,” Criminology and Public Policy, 1(1):119-148.
Lawrence W. Sherman and David Weisburd, (1995) "General Deterrent Effects of Police Patrol in Crime "Hot Spots": A Randomized, Controlled Trial," Justice Quarterly, 12: 625‑648.