Practice Profile: Police-Initiated Pedestrian Stops to Reduce Crime

Police-initiated pedestrian stops involve police officers’ stopping, questioning, and investigating pedestrians on the street, usually based on suspicion of criminal behavior or activity. Generally, the goal of the stops is to prevent or reduce the occurrence of crime and disorder. The practice is rated Promising for reducing measures of crime and displacement but was rated No Effects for improving measures of mental and physical health of citizens who were stopped by police.

Practice Goals/Practice Components

Police-initiated pedestrian stops on the street (also referred to as pedestrian stops, stop and frisks, Terry stops, street pops, stop and searches, etc.) are forms of engagement between law enforcement and citizens “whereby an officer stops and questions a pedestrian based on reasonable suspicion that the pedestrian is—or was recently—engaged in unlawful activity” (La Vigne et al. 2012, iv). The tactic involves police initiating a stop of an individual (or individuals) on the street for the purpose of investigation or questioning. Generally, the goal of the stops is to prevent or reduce the occurrence of crime and disorder.

Police-initiated stops can be reactive in nature, usually requiring the police to notice some prior indication of suspicious behavior or criminal activity to make the stop. Depending on the level of suspicion of police, a frisk or search of the stopped individual may be conducted. In contrast, police-initiated stops may also be part of larger proactive police interventions (Petersen et al. 2023). For example, as part of the Philadelphia Foot Patrol strategy (implemented in 2009), police officers patrolled targeted areas in the city for at least 8 hours a day. The officers would engage in various types of activities while patrolling assigned locations, including interviewing pedestrians.

The constitutionality of police-initiated stops was considered in the U.S. Supreme Court Case Terry v. Ohio (1968). The ruling provided police with discretion to conduct stops of individuals, given a reasonable suspicion that the individual has committed a crime or is in the process of committing a crime. The ruling also provided police with discretion to conduct frisks (or pat-downs) if there is reasonable suspicion that the individual is carrying a weapon (Petersen et al. 2023). The court places on the officers the responsibility of articulating a reasonable basis for frisking an individual but implicitly accepts the facts cited by police as reasonable (Sherman, Shaw, and Rogan 1995).

Practice Theory

Police-initiated stops may help prevent crime and disorder through the deterrent effect of police actions. For example, stops by police may increase the perceived certainty of apprehension of those individuals who may commit a crime. Further, if police-initiated stops are part of a larger proactive police response, the presence of additional police in a targeted neighborhood may also serve as a deterrent (Petersen et al. 2023).

Petersen and colleagues (2023) conducted a moderator analysis that compared the effect sizes related to crime/disorder outcomes from studies that looked at police-initiated stops in micro-geographic areas, neighborhoods/police beats, police districts/precincts, and macro-geographic areas (such as entire cities). There was one study that examined the impact of police-initiated stops in micro-geographic areas, four studies examined the impact of police-initiated stops in neighborhoods/police beats, three studies looked at the impact in police districts/precincts, and one study that looked at the impact in macro-geographic areas. Overall, the authors found that increases in the size of the geographic area targeted by the police stops led to decreases of between 3 percent and 4 percent in effect-size estimates (meaning larger areas received smaller crime-reduction benefits). However, the effect-size differences between the geographic areas were not statistically significant.

Petersen and colleagues (2023) also conducted a moderator analysis that compared the effect sizes related to mental health outcomes from studies that looked at police-initiated stops that occurred among adolescents compared with stops that occurred among adults. Six studies examined the impact of police-initiated stops involving adults, and two looked at the impact of stops involving youths. Overall, the authors found that the studies with youth samples were associated with a 74 percent increase in the odds of a mental health issue (for the treatment groups relative to the control groups), while adult samples were associated with a 32 percent increase. This difference was nearly statistically significant, and it suggests that police-initiated stops may have a harmful effect on the mental health of youths.   

These sources were used in the development of the practice profile:

These sources were used in the development of the practice profile:

Following are CrimeSolutions-rated programs that are related to this practice:

Police Foot Patrol, Philadelphia 2009

Kansas City (MO) Gun Experiment

Stop, Question, and Frisk in New York City

Why might a practice's outcome ratings differ from the ratings of specific programs encompassed by that practice?