Body-Worn Cameras

April 2021

Body-worn cameras (BWCs) are deployed to generate an objective record of police officers’ interactions with members of the public. Video documentation of such interactions is intended to enhance accountability and transparency by giving investigators and the public a view into cases of alleged misconduct. The knowledge that a recording is underway may also temper officer and community member behaviors, increasing lawful and respectful policing practices and reducing false complaints. Moreover, BWC video footage can supply useful evidence to corroborate a victim’s or officer’s statement, ensure chain of custody for recovered contraband, and identify people who engage in violence during mass protests.

Summary Assessment

  • Body-worn cameras can be effective in reducing public complaints, and potentially curbing police use of force, if the police agency has a strong accountability infrastructure in place (training, supervision, appropriate policies, oversight, etc.).

  • Body camera video footage has also been documented as a useful tool to support investigations, prosecutions, and public defense cases.

  • The most consistent research finding regarding BWCs is that they reduce community member complaints. It is unclear, however, how much of the reduction is due to changes in officer conduct and how much reflects changes in community member behavior.

  • Many officers do not activate their cameras consistently. To reap the full benefits of BWCs, policies should require officers to activate their cameras during interactions with members of the public, and agencies should hold them accountable for doing so.

  • New analyses suggest that the taxpayer and overall societal benefits of BWCs could outweigh the costs of purchasing and maintaining them. Benefits may include reduced investigation time, fewer complaint settlements, and lower administrative and oversight expenses, which would reflect the injuries and fatalities prevented by BWCs. However, because of considerable variation in the nature of BWC implementation and impact among agencies, cost-benefit findings alone should not govern an agency’s decision to invest in the technology.

  • Agency use of BWCs will best enhance transparency if video footage of high-profile incidents is released promptly to the public.

Current Practice and Research

While BWCs were in use by some law enforcement agencies prior to 2014, the fatal shooting that year of Michael Brown by a Ferguson, MO, police officer prompted calls for more transparency and accountability surrounding officer interactions with the public. Spurred by millions in federal grant dollars, police departments throughout the country began deploying cameras, seeking to enhance transparency of officer activities and aid in the identification and discipline of officers who engage in misconduct. By 2016, roughly 80% of large U.S. police agencies and nearly half of all agencies reported using BWCs with at least some portion of their patrol officers. This share has continued to grow in recent years, fueling expectations on the part of the public that most, if not all, police-community interactions will be captured on video. It is noteworthy, and troubling, that almost no federal law enforcement agencies routinely use BWCs. Studies have examined a wide range of outcomes associated with the cameras, such as their impact on officer use of force, volume of arrests, citations, proactive policing behaviors, and officer attitudes toward the cameras. Research also has explored the influence of BWCs on complaints from community members, their compliance and cooperation with officers, and their satisfaction with police interactions, criminal investigations, and police organizations.

The bottom line is that there continues to be uncertainty as to whether BWCs can reduce use of force, and research has yielded a mix of positive, negative, and null findings.

In addition, recent research has examined the role that body camera video footage plays in court. Drawing from cases of excessive use of force in the federal courts, one study found that BWC evidence can have an impact on summary judgment outcomes in favor of the defendant, but only when the video has a complete depiction of the event. Similarly, a study specific to domestic violence case outcomes found that cases with body camera footage had higher arrest rates, guilty pleas, and guilty verdicts. Both studies, however, found potential evidence of a “CSI effect,” whereby juries expect high-quality footage covering the entire event; in cases for which footage is absent, partial, or of low definition, jurors may be less inclined to view the evidence as persuasive.

Impact on Police Officer Behavior

Studies on the effects of BWCs on officer use of force are perhaps the most plentiful, and they have yielded mixed findings. Lum et al.’s comprehensive meta-analysis of 30 rigorous studies published through 2019 found an average effect of a 6.8% reduction in officer use of force associated with BWCs, but this reduction was not statistically significant. The authors also expressed uncertainty about this impact based on considerable variation in effects across studies. Indeed, a recent and large experimental study of BWCs in New York City found no reduction in use of force. However, a study employing a natural experiment examining over 1,000 police agencies nationwide (to examine fatal use of force) and 96 agencies in New Jersey (evaluating non-fatal use of force) found a 20% decline in non-fatal use of force, a 42% reduction in force resulting in injury, and a 41% reduction in officer-involved homicides among agencies that had adopted BWCs. Most recently, a meta-analysis by Williams et al. used Lum et al.'s data on studies specifically related to use of force and complaints and added Kim and Zimroth et al., recalculating the average effects of these two outcomes. That meta-analysis found an average reduction in use of force of 9.6%, although it should be noted that this effect is primarily due to the inclusion of the large effect found by Kim. We also note that there is debate over whether the Kim study would have satisfied the methodological criteria of Lum et al.'s systematic review. The bottom line is that there continues to be uncertainty as to whether BWCs can reduce use of force, and research has yielded a mix of positive, negative, and null findings. Agency policy on BWC usage varies, as does officer compliance with those policies. These inconsistencies in BWC use may explain the uneven impact of the technology documented in BWC evaluations. For example, while the majority of BWC programs mandate that officers activate their cameras for all interactions with community members, studies have shown that officers primarily activate their cameras when responding to violent or serious property crimes, and that they are more likely to make an arrest if their BWC was activated earlier in the interaction. This variation in when and how BWCs are used by officers may diminish their intended impact. Newer BWC “auto-triggering technologies” that activate cameras when officers exit their patrol car, pull their weapon from its holster, or are in the vicinity of another officer who activates his or her camera, may support improved documentation of police-community member interactions. Other officer behaviors examined by Lum et al. include the impact of BWCs on outcomes such as the volume of arrests and citations, proactive police activities (including traffic and pedestrian stops), assaults and resistance against officers, and calls for police service. As with use of force, researchers did not find a significant impact of BWC use on these behaviors, and study findings were again highly heterogeneous (yielding a mix of positive, negative, and null findings). Zimroth et al. also examined the impact of BWCs on officer stops. This study documented a 38.8% increase in the number of stops reported by officers equipped with cameras, but also found that these stops were less likely to be considered legal or to result in a summons. At first blush, this finding suggests that BWCs somehow led officers to conduct more stops. Instead, however, the authors theorize that officers equipped with cameras were more likely to report stops because they knew those interactions were being documented on video. For example, the Los Angeles Police Department’s Inspector General released a report that noted a significant number of stops captured on BWC video for which there was no corresponding police paperwork. These findings underscore the importance of understanding what types of policies can ensure camera activation and curb underreporting. Another challenge to any evaluation of BWCs is the growth in prevalence of civilian cell phone video and its potential impact on officer conduct independent of BWCs.

Impact on Community Member Behavior and Sentiment

The most consistent finding across studies with regard to BWCs’ influence on community member behaviors is a reduction of public complaints as a result of officers wearing cameras. Lum et al. found that cameras were associated with an average reduction of 16.6 % in public complaints across 22 studies, and similarly, Zimroth found that BWC implementation led to a 21.1% decrease in complaints in New York City. When incorporating Zimroth with the Lum et al. data, Williams et al. recalculates an average 16.9% reduction in public complaints against the police. However, as Lum et al. argue, it is unknown if the reduction in complaints is due to officers treating community members more lawfully and respectfully because they are being recorded or if community members are more reluctant to file complaints against BWC-equipped officers. Indeed, some share of people may be reticent to file legitimate complaints if they believe the footage will be used against them or that it may show their behavior in a negative light. Research findings on the impact of BWCs on community member perceptions of officer compliance with principles of procedural justice – the respectful, transparent, and impartial application of police processes – are mixed. Zimroth et al. conducted community member surveys before and after BWC implementation and found no difference in public perceptions of the police. One study of people who interacted with officers in Spokane, WA, and Los Angeles, CA, found that they were more likely to perceive camera-equipped officers as procedurally just. But others found no significant differences in community members’ perceptions of police legitimacy, satisfaction with their interaction with the officer, or views of police professionalism between officers with and without BWCs. Another study documented a remarkable lack of awareness or inaccurate recollection on the part of community members that the officers with whom they interacted were equipped with cameras, suggesting that any improvements in public perceptions were a result of BWC-equipped officers changing their behaviors. Regardless, officers should be trained to alert community members to the fact that the camera is present and has been activated as early as possible during the interaction. Such training would also remind officers to activate their cameras more routinely. Public attitudes toward BWCs have been generally positive but vary somewhat across different aspects of BWC application and evaluations of their potential benefits. For example, in a nationally representative sample, researchers found that the vast majority of people support requiring officers to be equipped with cameras (85%) and believe that cameras could increase transparency (91%) and reduce excessive use of force (80%). Substantially fewer respondents believed that cameras could improve police-community relations (66%), increase trust (61%), or reduce racial tensions (36%). In addition, surveys find that Black community members are less likely to believe that BWCs can improve police-community relations or officer accountability. This finding aligns with research showing that BWC-equipped police officers speak less respectfully to Black community members than White community members.

The most consistent finding across studies with regard to BWCs’ influence on community member behaviors is a reduction of public complaints as a result of officers wearing cameras.

Implementation Evaluation Findings

Some studies of BWC impacts have assessed how camera programs were implemented, from documenting the nature of policy development and dissemination surrounding their use to evaluating any camera-specific training that was delivered and tracking whether, when, and how often officers activated their cameras and complied with other BWC policies. This research finds that in many jurisdictions, BWCs were deployed prior to the development of policies that governed camera activation and specified how often supervisors were expected to review footage and hold officers accountable for identified misbehaviors and misconduct.

Video Use in Officer Misconduct and Use-of-Force Investigations

One important debate about BWCs is whether officers involved in use-of-force incidents should be allowed to view the video footage prior to making a formal statement or if that statement should be made first, particularly regarding incidents that involve potential misuse of force. Some policing experts argue that an officer should make a formal statement based on his or her own perspective and recollection, not from that of the camera, and that there is a possibility that the officer may shape his or her report to fit what is seen on video. The counterargument is that an officer should be able to see the footage to assist in making an accurate statement. Some agencies employ policies, under which officers may make their formal statements without the benefit of viewing BWC footage, review the footage, and, after viewing, have the opportunity to make amendments to their account of what transpired.2

Surveys find that Black community members are less likely to believe that BWCs can improve police-community relations or officer accountability. This finding aligns with the research finding that BWC-equipped police officers speak less respectfully to Black community members than White community members.

Camera Costs and Benefits

The costs of BWCs can range considerably and include not just the price of the cameras themselves but also video storage costs, software licenses, IT infrastructure, training, and personnel costs associated with responding to Freedom of Information Act requests for video, which can involve time-consuming, frame-by-frame redaction to protect the privacy of bystanders. All told, estimates of annual camera costs range from $1,100 to $2,900 per camera user.

Analyses found an average of $4.95 saved for every dollar spent on BWCs, with a low-bound estimate of $.95 and a high-bound estimate of $26.51.

A few studies of individual agencies have examined the technology’s relative costs and benefits. Ariel et al. examined the savings associated with BWC impacts on reduced public complaints, estimating the average cost of each complaint to be approximately $20,000 and concluding that $4 was saved in resolving complaints for every $1 spent on BWCs. Braga et al. analyzed savings to the Las Vegas Metropolitan Police Department associated with a 25% reduction in civilian complaints attributable to cameras, estimating that the agency realized benefits of $4,006 per BWC user per year. These benefits are driven primarily by the reduced cost of investigating complaints, owing to speedier investigations involving less officer labor. Most recently, Williams et al.’s research, drawing from 32 studies of over two dozen agencies, includes a robust cost-benefit analysis component that examined three outcomes: fatal police use of force, non-fatal police use of force, and civilian complaints against police. Resulting analyses found an average of $4.95 saved for every dollar spent on BWCs, with a low-bound estimate of $.95 and a high-bound estimate of $26.51.3 The authors estimate that roughly one quarter of the benefits accrue to government budgets (reduced investigation time, administrative burden, and complaint settlements) with the remainder of benefits attributable to societal savings (fewer costs due to reduced harm, lives saved).

Critical Policy Elements

  • Prior to deploying a BWC program, police agencies should examine short- and long-term costs associated with purchasing BWCs, training officers, and storing and managing BWC footage.
  • BWC policies should be created in partnership with community members and other local government agencies that will use the footage, including prosecutors’ and public defenders’ offices, advocacy organizations, and local police unions. The privacy implications of holding video of community members for long periods of time require departments to work with political leadership and community members to establish reasonable limitations on the use and storage of video. Camera footage should only be used for investigative, supervisory, and training purposes and not for the surveillance of officers or members of the public.
  • Before implementing a BWC program, agencies should develop policies guiding training requirements; expectations surrounding camera activation and when and how officers should notify community members that the camera is recording; and how video recordings will be tagged and uploaded by officers and secured, retained, and destroyed.
  • Agencies that choose to pay a third-party vendor to store camera footage should specify that they retain sole ownership of the video and require assurances that the vendor has sufficient protocols in place to ensure the data are secure and tamper-proof and will be destroyed at the close of the data-retention period.
  • In matters involving officer use of force or allegations of misconduct, officers should make an initial statement prior to viewing their BWC video, after which they can amend their statement.

  • Agency responses to officers who fail to comply with camera activation policies should be clearly articulated and equitably applied.

  • Specific procedures should be in place governing supervisors’ review of officer video footage. Specifically, policies should dictate how supervisors should respond when inappropriate behavior or misconduct is identified.

  • BWC footage should be available for use by supervisors in cases for which officers have an unusual volume of public complaints or use-of-force incidents compared to peers in similar assignments (e.g., units and shift).

  • Camera footage should also be made available for training applications, especially to illustrate examples of recommended or inappropriate responses to interactions with the public.

  • BWC policies should outline how and within what timeframe footage will be released to the public and should specify reasons why video release may be delayed. The policies should also detail how camera footage should be redacted to protect the identity and privacy of bystanders, how it is secured, and what measures are in place to prevent data tampering.

  • Agencies should be subject to routine independent compliance audits, such as those employed in the state of Minnesota and Austin, TX, to ensure compliance with policies governing when and how BWCs are to be used.

Expected Impacts

Preventing Misuse of Force

Although the research is still equivocal regarding the impact of BWCs on use of force, reductions in misuse of force may be more likely when officers are held accountable for activating their cameras during all interactions with members of the public or when activation is accomplished via auto-triggering technology.

Enhancing Transparency and Accountability

Improvements in accountability depend on the strength of agencies’ overall accountability infrastructures for responding to misconduct revealed by video evidence. If BWC video is used routinely in officer trainings, performance reviews, BWC footage supervisory audits, and misconduct investigations, cameras hold promise for uncovering officer misconduct and enhancing officer accountability. In order for BWC programs to boost transparency, footage of high-profile cases involving allegations of misconduct and excessive force needs to be publicly released promptly. In addition, cameras may lead officers to report stops of members of the public that they wouldn’t otherwise, enhancing transparency of those activities.

Strengthening Community Trust

Community members differ in their support of BWCs and their belief that the technology will enhance transparency and police legitimacy, with Black people less likely than White people to believe that cameras will be effective in this regard. Moreover, at least three studies have observed that members of the public are largely unaware of whether officers are equipped with cameras. Both findings suggest that cameras alone will not strengthen community trust. However, trust may be enhanced to some degree when agencies use footage to hold officers accountable.

Reducing Racial Disparities

There is no known research indicating that BWCs reduce racial disparities in policing practices or outcomes for members of the public.

Ensuring Officer Safety

Research evidence is mixed on whether officers equipped with body cameras are more or less likely to experience assault or injury.

Promoting Public Safety

There are no rigorous studies that examine the degree to which cameras may reduce the incidence of crime in the community.