Practice Profile: Body-Worn Cameras’ Effects on Police Officer Behavior

Evidence Rating for Outcomes

Justice Systems or Processes | Use of force

Crime & Delinquency | Assault on officer/officer injuries/resistance

Crime & Delinquency | Multiple crime/offense types

Justice Systems or Processes | Officer-initiated calls for service

Crime & Delinquency | Traffic stops/traffic tickets

Justice Systems or Processes | Field interviews/stop and frisk

Date: This profile was posted on January 07, 2022

Practice Goals

Body-worn cameras are recording devices worn by law enforcement officers. These cameras record activities, events, and interactions with members of the community from the officer’s vantage point. Law enforcement uses body-worn cameras for numerous reasons. For example, the cameras can capture an objective record of events, rather than forcing agencies to rely solely on written reports from officers or accounts from citizens, thereby potentially encouraging mutual accountability during encounters. Additionally, body-worn cameras are also thought to improve police conduct and transparency, especially regarding police use of force (Lum et al. 2020).

Practice Components

Officers can wear body-worn cameras on their clothing (on the chest, shirt pocket, collar, or shoulder) or mounted on a helmet or glasses. The cameras are small enough to be worn without encumbering officers in their regular work (Ariel, Farrar, and Sutherland 2015).

Body-worn cameras can be used in numerous ways, depending on the jurisdiction employing them. For example, some police departments give body-worn cameras only to officers in specialized units, such as tactical, gang, undercover, or K9 units. Other departments make use of body-worn cameras for all uniformed officers. The function of the body-worn camera can also vary across jurisdictions. Some cameras turn on by default and remain in operation through the officer’s entire shift (though there are some exceptions for interactions with informants, or in cases of serious sexual assault). Other cameras are turned on manually by the officers wearing them. Law enforcement officers can be instructed to inform citizens that the body-worn camera is on and recording them, though some agencies do not require such notifications (Lum et al. 2020).

Practice Theory

The use of body-worn cameras is rooted in two theories: deterrence theory and perceived social surveillance. Deterrence theory states (in part) that the certainty of getting caught and punished for wrongdoing decreases the likelihood of engaging in wrongdoing. In the case of body-worn cameras, the camera serves as a “credible threat” in the detection of negative behaviors, such as the use of excessive force by police officers, and thus decreases the likelihood of those behaviors (Ariel et al. 2016). Additionally, research proposes that people are more likely to adhere to social norms and change their conduct in a socially desirable direction when they are aware of being observed (Farrar and Ariel 2013). When civilians are aware they are being monitored through a body-worn camera, they are less likely to be aggressive and more inclined to cooperate with law enforcement officers. In turn, police officers would be less likely to react inappropriately by behaving in a rude manner or using excessive force.

Justice Systems or Processes | Use of force

Aggregating the results from 26 studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact on officers’ use of force.

Crime & Delinquency | Assault on officer/officer injuries/resistance

Aggregating the results from 15 studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact upon assaults on officers, officer injuries, and resistance to officers.

Crime & Delinquency | Multiple crime/offense types

Aggregating the results from 13 studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact on arrests.

Justice Systems or Processes | Officer-initiated calls for service

Aggregating the results from eight studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact on general measures of officer-initiated calls for service or proactivity.

Crime & Delinquency | Traffic stops/traffic tickets

Aggregating the results from five studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact on traffic stops or tickets (specific measures of proactivity by officers).

Justice Systems or Processes | Field interviews/stop and frisk

Aggregating the results from five studies, Lum and colleagues (2020) found that the use of body-worn cameras by police officers did not have a statistically significant impact on stop-and-frisk stops also called pedestrian stops and field interviews (a specific measure of proactivity by officers).

Meta-Analysis Snapshot
	Literature Coverage Dates	Number of Studies	Number of Study Participants
Meta Analysis 1	2012-2020	30	0

Meta Analysis 1

Using meta-analytic techniques, Lum and colleagues (2020) analyzed the effects of officers wearing body-worn cameras on various outcomes. To identify eligible evaluations, they conducted a search of the Global Policing Database at the beginning of 2019 for studies published between Jan. 1, 2004, and Dec. 31, 2018, using key terms such as camera, video, and body-worn camera. A supplemental search to capture additional evaluations was conducted for studies published between Jan. 1 and Sept. 20, 2019. To be considered eligible for inclusion, a study had to use either experimental or quasi-experimental methods. An experimental study was included if the treatment was randomly assigned to the unit of analysis, and a quasi-experimental study was included if a comparable comparison group (created by propensity scores or other matching techniques achieved through the use of statistical controls) was evident. Populations of interest were both law enforcement officers and civilians; therefore, officers, groups of officers, shifts, non–law enforcement personnel, and geographic areas were eligible as units of analysis. All interventions involving a law enforcement officer wearing a body-worn camera were eligible. The outcomes were complaints against officers, use of force, arrests, officer-initiated calls for service, field interrogation stops, traffic stops or tickets, incident reports written, response time, time on scene, ordinance citations, civilian calls for service, assaults on officers, officer injuries, and resistance against officers.

Thirty studies were identified as eligible for inclusion. Across the 30 studies, 11,913 officers were involved. The majority of studies (n = 17) took place in the United States, 2 took place in the United Kingdom, 1 took place in the Republic of Uruguay, and 10 took place in an unidentified location. Twenty studies were randomized controlled trials, and 10 used quasi-experimental designs. In 25 studies, body-worn cameras were used by uniformed patrol only, in 1 study they were used by specialized units only, and in 4 studies they were used by both uniformed patrol and specialized units. For the CrimeSolutions review of this meta-analysis, the outcomes of interest were use of force (26 studies), assault on officer/officer injuries/resistance (15 studies), arrest incidents (13 studies), officer-initiated calls for service (8 studies), traffic stops/traffic tickets (5 studies), and field interviews/stop and frisk (5 studies).

Poisson-based regression models (including quasi-Poisson and negative binomial) were used to estimate the effect of body-worn cameras on the outcome variables.