BJA's National Body-Worn Camera Toolkit is a clearinghouse for criminal justice practitioners.
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.
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:
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.
| Program | Rating | Description | Study Year |
|---|---|---|---|
| Police Body-Worn Cameras (Boston, Massachusetts) | Effective | This involves police officers wearing cameras on their uniforms to improve the civility of their interactions with citizens. The program is rated Effective. There were statistically significant reductions in citizen complaints against police and police use-of-force reports for officers who wore cameras, compared with those who did not, and statistically significant reductions in complaints against control officers in the treatment districts, compared with officers in the untreated districts. | 2020 |
| 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 |
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.
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.
VGA, HD 720P, and 1080 HD are predominant standard resolutions. The higher the resolution, the more storage is needed. Estimates below were created assuming H.264 compression with medium to high motion at 30 frames per second (fps) derived using a heuristic formula widely used in industry. Actual storage utilized is dependent on scene complexity and the motion of the video captured. Consider what sort of analysis may be conducted on the video before selecting a resolution. For example, if forensic video analysis is anticipated, a resolution less than VGA is not recommended.
[note 1] RCTs provide the highest degree of confidence that observed effects are the result of the program and not of other factors.
[note 2] Hyland, S., Body-Worn Cameras in Law Enforcement Agencies, 2016, Bureau of Justice Statistics, November 2018. Note that this survey excluded federal agencies, sheriffs’ offices with only jail or court duties, and special-purpose agencies such as transit police and campus police.
[note 3] Lum, C., et al, Research on body-worn cameras: What we know, what we need to know, Criminology & Public Policy, pp. 93 – 118, March 24, 2019
[note 4] CrimeSolutions is the NIJ-funded federal clearinghouse of evaluation research, showing what works, what does not work, and what is promising across broad expanses of criminal and juvenile justice programs and practice. Learn more about CrimeSolutions.
[note 5] Home Office Centre for Applied Science and Technology, Body-Worn Video Technical Guidance (pdf, 10 pages), May 2014
[note 6] Scientific Working Group on Imaging Technology, Recommendations and Guidelines for Using Closed-Circuit Television Security Systems in Commercial Institutions, Version 3.0, June 8, 2012.
National Institute of Justice, "Research on Body-Worn Cameras and Law Enforcement," January 7, 2022, nij.ojp.gov:
https://nij.ojp.gov/topics/articles/research-body-worn-cameras-and-law-enforcement
This page is updated periodically as new research findings or information from NIJ-funded projects becomes available.