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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 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.

These mixed findings are further reflected in findings from evaluations of seven body-worn camera programs that have met the stringent criteria for inclusion in NIJ’s CrimeSolutions[4]. Across these evaluations, researchers looked at a range of outcomes, including use of force, citizen complaints, arrests, and assaults on officers.

Five of the body-worn cameras programs were rated 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. Read the program profile Police Body-Worn Cameras (Birmingham South, UK).
  • In Rialto, CA, evaluators found a statistically significant reduction in police use-of-force but no significant difference in citizen complaints. Read the program profile Police Body-Worn Cameras (Rialto, Calif.).
  • 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. Read the program profile Body-Worn Cameras (Las Vegas Metropolitan Police Department.
  • 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. Read the program profile Police Body-Worn Cameras (Phoenix, Arizona).
  • In a separate study in Phoenix, AZ, 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. Read the program profile Police Body-Worn Cameras for Intimate-Partner Violence Cases (Phoenix, Ariz.).

Two of the body-worn camera programs evaluated were found to have no effect 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. 

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.

Market Survey of Body-Worn Cameras for Criminal Justice

The NIJ-funded NLECTC Sensor, Surveillance and Biometric Technologies Center of Excellence conducted a market survey on body-worn cameras for criminal justice. The survey, updated in 2016, aggregates and summarizes information on a number of makes and models of body-worn cameras available today, including the approximate costs of each unit.

Read an abstract and access the full report.

Date Modified: January 7, 2022

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

Date Published: January 7, 2022