What is the Evidence on Police Technology?
Police technology is listed under “What do we need to know more about?” on our Review of the Research Evidence because for the technologies listed below, research is in its infancy, particularly research related to fairness and crime control effectiveness.
Body worn cameras have quickly become a prominent part of discussions about police reform. Research on the effects of body-worn cameras on police use of force, complaints, citizen behavior is beginning to accumulate and studies in progress will provide more data on the effects of cameras on citizen perceptions of police legitimacy, officer behavior, and crime. As Lum et al. (2015) caution in a recent report, it is premature to reach strong conclusions on the effects of body worn cameras. The Center for Evidence-Based Crime Policy body-worn camera page will continue to be updated as new research is added to the evidence base. There is suggestive evidence to date that officers wearing cameras may be less likely to receive complaints. The evidence on police use of force is less conclusive, as is the data on whether citizens act differently when officers are wearing cameras.
ShotSpotter or other Acoustic Gunshot Locations Systems are designed to quickly locate the location of a gunshot after shots are fired and then alert police about the gunfire. The idea is that police could more quickly respond to gunfire incidents to make arrests and the system could potentially act as a deterrent to gunfire as the risk of detection increases. Mazerolle and colleagues (1999) evaluated the systems in use in Redwood City, CA (ShotSpotter) and Dallas, TX (SECURES) and found that the systems could fairly accurately identify the location of gunfire. The systems could increase officer workload because many gunshots were previously unreported to police. The systems also did not tend to help officers make more arrests, as shooters tended to quickly leave the scene. Mazerolle et al. suggest the technology could be useful as a problem solving tool, as it could aid police efforts to analyze high gunfire locations.
More recently, Mares and Blackburn (2012) evaluated the effectiveness of a gunfire location system in St. Louis. They found the system may be related to a decrease in gun-crime related calls for service, but not in reported gun incidents. The authors conclude that the decrease in calls for service is not necessarily a positive development, as it may suggest that residents are less likely to call in incidents because they think the system will take care of it for them. Choi, Librett, and Collins (2014) found that a ShotSpotter system in southeastern Massachusetts was associated with decreased police response time for gunshot incidents, but there was no improvement in gun-related case resolution (e.g., making arrests or prosecuting suspects).
Unmanned Aerial Vehicles (drones)
While the police use of drones has become increasingly popular (and controversial), there is no evaluation research on the effectiveness or cost-effectiveness of the use of drones. While the technology may enhance the ability of police to do surveillance work versus helicopters or other more traditional approaches, it is not clear whether any benefits that do exist will outweigh the high cost of the devices, both in terms of monetary cost and potential lowered citizen perceptions of legitimacy as a result of concerns about civil liberties.
License Plate Readers (LPR)
Lum and colleagues (2010) tested the effectiveness of license plate readers (LPR) in deterring crime and automobile crime in a two-jurisdiction randomized experiment. License plate readers take images of vehicle license plates and compare them to a database of information on vehicles associated with particular crimes and offenders. The hot spot approach to LPR use was not associated with a significant crime decline. Koper and colleagues (2013) found that LPR in Mesa, AZ led to an increase in the number of plates scanned (compared to checking plates manually) and led to increases in the number of hits for stolen vehicles, arrests for stolen vehicles, and recoveries of stolen vehicles (see Taylor et al., 2012). There was some evidence of residual deterrence effects on drug crime in the locations where LPR was used.