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Research on Body-Worn Cameras and Law Enforcement

Date Published
January 7, 2022

Body-worn cameras are widely used by state and local law enforcement agencies in the United States. They are worn principally by officers in the performance of duties that require open and direct contact with the public. Despite their widespread and growing adoption, the current evidence regarding the effectiveness of body-worn cameras is mixed. Some studies suggest that body-worn cameras may offer benefits while others show either no impact or possible negative effects. The mixed results of these studies strongly imply that additional research is needed. In particular, more studies employing randomized control trials [1] are needed.

Use of Body-Worn Cameras

In November 2018, the Bureau of Justice Statistics (BJS) published a report on the use of body-worn cameras by law enforcement agencies in the United States in 2016.[2] This report showed that:

  • 47% of general-purpose law enforcement agencies had acquired body-worn cameras; for large police departments, that number is 80%.
  • Among agencies that had acquired body-worn cameras, 60% of local police departments and 49% of sheriffs' offices had fully deployed their body-worn cameras.
  • Overall, in agencies that had acquired body-worn cameras there were 29 body-worn cameras in service per 100 full time officers (expected to increase to 50/100 by late 2017 based on the 2016 data).
  • About 86% of general-purpose law enforcement agencies that had acquired body-worn cameras had a formal body-worn camera policy.
  • Agencies not using body-worn cameras stated cost (hardware acquisition, video storage, system maintenance) to be the primary disincentive.

Are Body-Worn Cameras Effective?

According to the 2018 BJS report, the main reasons (about 80% each) that local police and sheriffs’ offices had acquired body-worn cameras were to improve officer safety, increase evidence quality, reduce civilian complaints, and reduce agency liability.

Research does not necessarily support the effectiveness of body-worn cameras in achieving those desired outcomes. A comprehensive review of 70 studies of body-worn cameras use found that the larger body of research on body-worn cameras showed no consistent or no statistically significant effects.[3] This meta-analysis was rated by CrimeSolutions and resulted in a No Effects rating for the impact of body-worn cameras on use of force, assaults on officers, officer-initiated calls for service, arrests, traffic stops and tickets, and field interviews (i.e., stop and frisk). See Practice Profile: Body-Worn Cameras’ Effects on Police Officer Behavior. This profile is based on a meta-analysis published in 2020. 

These mixed findings are further reflected in findings from evaluations of ten body-worn camera programs that have met the stringent criteria for inclusion in NIJ’s CrimeSolutions, see Table 1.[4] Across these evaluations, researchers looked at a range of outcomes, including use of force, citizen complaints, arrests, and assaults on officers. Four of the body-worn camera programs evaluated were found to have no, limited, or even negative effects.

Based on these reviews and the existing research on the impact of body-worn cameras use, it is clear that further research is essential to determine the value of body-worn cameras use and potentially the more effective ways body-worn cameras could be deployed. Given the growing use of body-worn cameras, it would be best to build in rigorous evaluations as law enforcement agencies expand their use of this technology. 

Table 1: Body-Worn Camera Programs Rated by NIJ's CrimeSolutions
Program Rating Description Study Year
Effects of Body-Worn Cameras on Reducing Rates of Citizen Fatalities Promising Researcher looked at law enforcement’s use of cameras to record interactions with civilians to reduce citizen fatalities using a subsample of U.S. police departments drawn from the Bureau of Justice Statistics’ Law Enforcement Management and Administrative Statistics Body-Worn Camera Supplement. Based n that study, CrimeSolutions rated the use of body-worn cameras to reduce citizen fatality rates as Promising. Agencies that acquired cameras had statistically significant decreases in fatal police–citizen encounters after three years, compared with agencies that did not acquire cameras. There were no statistically significant differences in fatal encounters between a reduced set of agencies with cameras and matched agencies without cameras. 2021
Police Body-Worn Cameras (Birmingham South, UK) Promising In Birmingham, UK, evaluators found that deploying body-worn cameras resulted in a statistically significant reduction in citizen injury, but no statistically significant reduction in officer use of force or injury. 2015
Police Body-Worn Cameras (Rialto, Calif.) Promising In Rialto, CA, evaluators found a statistically significant reduction in police use-of-force but no significant difference in citizen complaints. 2015
Body-Worn Cameras (Las Vegas Metropolitan Police Department Promising In Las Vegas, Nevada, and evaluation of the Metropolitan Police Department’s use of body-worn cameras revealed that the use of body-worn cameras resulted in a statistically significant reduction in both complaints and use of force. 2018
Police Body-Worn Cameras (Phoenix, Arizona) Promising In Phoenix, AZ, evaluators found body-worn camera use resulted in statistically significant decreases in citizen complaints, and there were mixed results regarding camera use on arrest rates. There were no statistically significant differences in citizen resistance. There was a statistically significant increase in use of force, and less proactive, officer-initiated contact. 2021, 2017
 Police Body-Worn Cameras for Intimate-Partner Violence Cases (Phoenix, Ariz.) Promising Evaluators looked at a program that equips police with on-officer cameras to record contacts with civilians during intimate-partner violence incidents. Camera use was statistically significantly more likely to result in arrests, charges filed, cases furthered, and both guilty pleas and verdicts. There was no statistically significant difference in sentence length. However, there was a statistically significantly greater reduction in case processing time in cases not involving a camera. 2016
Police Body-Worn Cameras (Washington, D.C.) No Effects In Washington, DC, evaluators found no statistically significant differences in police use-of-force, nor the number of citizen complaints.  2017
Police Body-Worn Cameras in Eight Police Departments in the United Kingdom and United States No Effects A multi-site evaluation of eight departments in the US and the UK found, overall, found no statistically significant differences in police use of force, number of citizen complaints, or number of arrests for disorderly conduct for police officers who wore body-worn cameras, compared with officers who did not wear them. 2016
New York City Police Department Body-Worn Cameras’ Effects on Civility and Lawfulness of Police–Citizen Encounters and Policing Activities No Effects In New York City, camera use had no statistically significant effects on number of arrests, arrests with force, and summonses issued after 1 year. Officers wearing cameras had statistically significant reductions in complaints filed against them and made more stop reports. Camera use resulted in a statistically significantly reduced likelihood of lawful stops and frisks but fewer subjects searched.  2021

Milwaukee (Wisconsin) Police Department Body-Worn Cameras

No Effects In Milwaukee, camera use had no statistically significant effects on officers’ total number of proactive activities, specifically on the number of traffic stops or business checks, nor on arrests, citizen complaints, and use-of-force incidents. Officers with cameras conducted statistically significantly fewer subject stops, and statistically significantly more park and walks. 2020, 2018

Primer on Body-Worn Cameras for Law Enforcement

Developed by the NIJ-funded NLECTC Sensor, Surveillance and Biometric Technologies Center of Excellence, A Primer on Body-Worn Cameras for Law Enforcement provides an introduction to body-worn camera systems. The  report discusses the functions and features of body-worn camera systems and highlights issues and factors that law enforcement organizations should consider before and during implementation.

Read an abstract and access the full primer.

Technical Guidance on Body-Worn Camera Technologies

Agencies should consider how body worn cameras will meet their mission needs and requirements prior to procurement and use of the technology. To provide general guidance to law enforcement practitioners, NIJ, NIST and the FBI developed a table listing operating characteristics and associated functionality descriptions based on existing technical resources about criminal justice use of video.[5],[6] The operating characteristics and associated functionality descriptions in the table can help agencies determine what they need as they consider the commercial products available.


Date Modified: January 22, 2023

This page is updated periodically as new research findings or information from NIJ-funded projects becomes available. 

Date Published: January 7, 2022