Research on Body Worn Cameras

Abstract

As police departments across the United States equip officers with body worn cameras (BWCs), research has focused on the technology’s impact on police interactions with citizens, officer misconduct, officer use of force, and false allegations against police. Given the large number of police agencies implementing BWCs across the country (numbering in the thousands), there will be a growing number of opportunities for BWC evaluations and expectations that these programs will be evaluated. Studying the implementation of BWCs presents a number of challenges to both researchers and police agencies, particularly when large police organizations are involved. Drawing on our experiences involving a BWC experiment with the Las Vegas Metropolitan Police Department, this article discusses the programmatic challenges of implementing a BWC program in a large agency (technical, political, and administrative) while simultaneously evaluating the program using a randomized controlled trial design.

Keywords

body worn camera randomized controlled trial

Introduction

This article describes a randomized controlled trial (RCT) designed to study the impact of body worn cameras (BWCs) on police officer behavior in the Las Vegas Metropolitan Police Department (LVMPD), a large police agency with approximately 1,100 police officers assigned to the patrol division. We discuss the process evaluation component of a National Institute of Justice-funded research project that entailed both process and impact evaluation components.

The implementation of BWCs grows at a rapid pace in American police agencies. In Fall 2015, the Bureau of Justice Assistance (BJA) and the Office of Justice Programs (OJP) distributed over $19 million in funding to 73 U.S. police agencies for the purposes of enhancing or implementing BWC programs (BJA, 2016a). This funding initiative is part of a 3-year plan of the White House and the U.S. Department of Justice (2015) to provide over $70 million to police agencies for the implementation of 50,000 BWCs. In May 2015, the National Conference of State Legislatures reported that at least 30 states were considering legislation regarding BWCs, with one-half of them requiring or recommending the use of BWCs by police (BJA, 2016b). BJA reports that 4,000 to 6,000 U.S. police agencies have implemented or plan to implement BWCs (BJA, 2016b).

This anticipated growth in the utilization of BWCs by police brings with it the expectation and need for basic and applied research regarding the implementation and use of this technology by police, and regarding the impact of the technology on police officers, police agencies, civilians, and society in general. The process evaluation reported in this article addresses the need for applied research regarding BWCs and may be helpful to researchers and practitioners by providing information about the challenges encountered when implementing and studying BWCs in a large police agency, building on Drover and Ariel (2015) who discuss similar issues regarding BWC experiments. First, we briefly discuss background on BWCs, BWC implementation, and the RCT methodology. We then describe the LVMPD BWC experiment while highlighting several important implementation challenges encountered by the LVMPD and the research team, including both the challenges of RCTs and the challenges of BWC implementation in a large police agency. Finally, we discuss how some of these challenges were overcome and how some still remain.

Background

Body worn cameras

Over the past decade, much attention has been paid to issues regarding the utilization of technology in policing and other sectors of the justice system; much of this attention has been directed toward issues regarding information systems, specific applications of technology (e.g., TASER™ electronic control devices, CCTV surveillance cameras, License Plate Recognition systems, in-car cameras), and computerized mapping and technology needs assessments. Byrne and Marx (2011), for example, reviewed recent literature and developments concerning the relationship between technological innovation in policing and crime prevention, offering some useful prescriptions for improving our understanding of this link. BWCs have emerged as one of these recent technological innovations. Despite the rapidly increased interest in body-worn cameras in policing, however, very little of the literature has focused on whether BWCs improve police behavior or are cost effective.

The interest among police agencies in using BWCs to increase public transparency and reduce false claims of police misconduct is ever growing due to recent police critical incidents (e.g., Michael Brown, Ferguson, MO) and the recommendations made by the President’s Task Force on 21st Century Policing (President’s Task Force on 21st Century Policing, 2015; Wyllie, 2012). This increased interest from both community and federal stakeholders has led to a significant growth in the number of police agencies purchasing this technology.¹

Despite the rapid momentum BWCs have taken, there is little randomized experimental research on this class of technology, its effects, and whether it has any impact on police behavior (Drover & Ariel, 2015). According to the Center for Evidence Based Crime Policy, only eight empirical studies on BWCs have been conducted in the Unites States, and only two of these employ RCTs (Lum, Koper, Merola, Scherer, & Reioux, 2015). These studies were completed within the last 2 years. The swift interest in BWCs has also led to an increase in BWC research; the Center also notes 19 empirical studies on BWCs are currently underway, 8 of which employ RCTs (Lum et al., 2015). Despite the growth in BWC research, the implementation of BWCs in police agencies across the country significantly outpaces current research efforts. While some studies have shown reductions in use of force, citizen complaints, and a potential civilizing effect to varying degrees, others also note the need for more comprehensive and rigorous research in this area (Drover & Ariel, 2015; Katz, Kurtenbach, Choate, & White, 2015).

Implementation of technology in policing can have serious and unintended effects if not carefully considered, monitored, and evaluated. For example, police officers can impact the implementation of technology based on their experience and level of comfort with it (supervisor experience and attitudes can also have an effect); the internal police agency environment (i.e., policies, budgets, training) can support or hinder implementation of technology; and cost issues can arise, especially concerning sufficient recognition of—and planning for—correlated technology costs, such as the high cost of data storage and preservation.

BWC Implementation Challenges

As police agencies across the United States have come to realize, the introduction of BWCs to their organizations presents a number of technological, political, and administrative challenges that go well beyond the purchasing of BWCs and the equipping of officers. From the technological perspective, the BWC units themselves (camera and battery pack) represent only a small portion of the overall costs. Far more expensive are infrastructure costs (such as docking stations that allow for the upload of video data) and the costs of video storage, which can be particularly high in large organizations where video recordings can amount to petabytes of information.² Agencies also face a number of data management issues, such as facilitating access to videos for authorized system users within and outside the organization, processing video record requests from the media and other members of the public, and redacting portions of recordings prior to distribution as legally appropriate.

Agencies also face political challenges, both from within the organization and from outside entities. Internally, for example, police unions have opposed BWCs over a number of issues, including the opinion that BWCs could jeopardize officer safety (if the technology causes police to hesitate in their actions) or the idea that the technology may be a mechanism for administrators to spy on their employees. Union concerns may be more perception than reality, but for many agencies, a strong union that opposes BWCs can represent a major obstacle in terms of implementing a BWC program. On the other hand, outside pressures can force agencies to implement a BWC program before it is ready. In today’s climate, police departments are under significant pressure from community and interest groups to equip officers with BWCs on the assumption that the technology will improve transparency and enhance trust between police and citizens. Many organizations are, therefore, left in a difficult position as they negotiate between the rights of their officers and the demands of the community.

Police agencies also confront numerous other administrative concerns when it comes to implementing BWCs. Proper training protocols, for instance, have to be established for both the use of BWCs and the management of video records. Departments also have to design a BWC policy that meets the needs of the community, protects the rights of citizens (and officers), and conforms to appropriate state laws (such as public disclosure of video data). For example, there are concerns regarding community member privacy versus the need for information pertinent to public safety goals (e.g., should officers comply when asked to turn their BWC off, or when they are in situations in which there is a reasonable expectation of privacy?). Similarly, should officers wearing BWCs deactivate them when encountering victims in vulnerable situations, confidential informants, juveniles, or individuals in emotionally stressful situations or in mental health crises?

In addition, agencies have to make decisions in terms of how and where a BWC program will be administered within the organization. This decision is sometimes complicated by the bureaucratic nature of large police agencies and the fact that BWCs touch on various units and divisions within the bureaucracy. Arguments can be made that BWC implementation should be administered by at least several different internal units: the IT department since it is generally responsible for maintaining technologies; the training bureau because it is responsible for the proper use of BWCs by officers; the patrol division because its officers deploy the technology; the data analysis unit because it is responsible for securing and managing video recordings; or internal affairs or other investigative units since they are responsible for reviewing evidence from video files.

Randomized Controlled Trials

RCTs are considered the gold standard for evidence-based research because they are the methodology best suited to establish whether the introduction of an experimental stimulus causes change in a specified outcome variable. In typical RCT designs, the individual units under study are randomly assigned into either a treatment group or a control group (Shadish, Cook, & Campbell, 2002). Random assignment to groups is the key, as it establishes equivalency between groups and helps to reduce concerns over selection bias and other threats to causal validity. After random assignment, those in the treatment group receive an experimental condition while those in the control group do not. Since the two groups are initially equivalent as the result of randomization, if they differ significantly after the treatment group receives the experimental condition, one can conclude that the experimental stimulus is the cause of the difference.

The RCT design has a long history in medical studies and has grown in popularity in the social sciences for its advantages over other research methods that are considered to be less rigorous (Sherman et al., 1998). Indeed, RCTs are often now encouraged by funding agencies for their perceived benefits over quasi-experimental and observational studies. Despite the advantages of RCTs, however, the method has been criticized on a number of grounds. Given the nature of the population and sample, for example, random assignment may not be possible or desirable. In addition, some argue that the time and cost necessary to establish the conditions for an RCT are prohibitive, particularly when less expensive but still rigorous alternative methods are available that generally achieve similar results (Concato, Shah, & Horwitz, 2000; Sanson-Fisher, Bonevski, Green, & D’Este, 2007). External validity can also be a problem when it comes to RCTs, especially if the sample is uncharacteristic of the population from which it was drawn or from populations to which it is meant to generalize (Sanson-Fisher et al., 2007). Furthermore, when RCTs are conducted outside of the laboratory setting, experimental conditions can be difficult to monitor and maintain. This is often the case in criminal justice policy studies where the rigidity of RCT designs conflicts with political concerns, operational realities, or commonly held organizational beliefs (Braga, 2013).³

While RCT randomization procedures minimize many threats to causal validity, other threats still remain. Attrition can be a problem in any long-term experiment, for example, especially if individuals from one group drop out at a different rate than those in the other group. Contamination of the treatment effect can also be a major concern if members from treatment and control groups are somehow in contact with each other.

Finally, there are sometimes ethical concerns raised when RCTs are used to test the efficacy of treatments (see, e.g., Clarke & Cornish, 1972; Erez, 1986; Esbensen, 1991; Geis, 1967). Is it fair, for example, to provide a presumably effective treatment to one group of individuals (as in the case of a drug addiction treatment modality) or communities (as in the case of an innovative approach to community policing) while withholding the same treatment from other (control group) individuals or communities? While the research community may readily understand the need for rigorous testing of the assumption regarding treatment effectiveness, others may question the fairness of the unequal application of social remedies.

A number of crime and justice scholars suggest that there is a “moral imperative” in pursuing the most rigorous evaluation designs to discover whether a program is effective (see, e.g., Boruch, 1975; Weisburd, 2003). Isolating the effects of treatments or programs from other confounding aspects of selection or design is viewed as one of the evaluator’s most important obligations to society. When the evaluation evidence base is largely informed by weak designs, practitioners risk implementing certain treatments or programs as effective crime prevention practices when they are not; this can lead to significant economic and social costs. Moreover, as Weisburd (2010) demonstrated, the growth of criminological experiments in a broad range of real-world settings that have been carried out in an ethical manner demonstrates that these concerns are, in most cases, based in folklore rather than facts.

LVMPD BWC Experiment

The LVMPD BWC experiment encountered many of the challenges associated with conducting an RCT within a large police agency, along with the added complications of implementing a new BWC program. By way of background, the LVMPD is the largest police department in Nevada, with approximately 2,500 sworn personnel. As of 2013, approximately 1,100 of these sworn personnel were uniformed officers assigned to the patrol division. The patrol division is divided geographically into eight “area commands.” The area commands, each headed by a captain, have primary responsibility for preventive patrol, responding to calls for service, and other proactive activities.

LVMPD began pilot testing BWCs with a small group of officers in 2011, around the time that the agency was under intense scrutiny for its use of force policies that ultimately resulted in a Collaborative Reform process with the Department of Justice (Stewart, Fachner, Rodriguez, & Rickman, 2012). The pilot testing period served as an opportunity for the agency to experiment with different vendors, see how officers responded to the technology, and draft the department’s initial BWC policy. By 2013, a vendor was selected, a policy was in place, and the agency’s experience with BWCs and willingness to implement them set the stage for the LVMPD BWC experiment (which the National Institute of Justice agreed to fund). In 2014, LVMPD would begin to officially deploy 200 BWCs on officers with the BWC experiment serving as the initial mechanism of their deployment.

The LVMPD BWC experiment was ostensibly a straightforward design. Duty rosters from the area commands would provide the sampling frame of 1,100 officers from which a target sample of 400 could be drawn. These 400 would then be randomly assigned into treatment and control groups. After the 200 officers in the treatment group received the appropriate training and were issued BWCs, officers in both groups would then be monitored for a period of 1 year.⁴ Comparisons on the dependent variables of interest (including use of force, complaints of misconduct, and measures of proactive activities) between the BWC treatment officers and the control officers could then be assessed.

While seemingly straightforward, a number of challenges surfaced that are related to the stringency of RCT designs, the nature of BWC implementation, and the specific context of LVMPD. One of the first methodological concerns identified was the issue of attrition since the analysis plan required officers to remain in the trial for 1 year. The primary methodological concern, however, was related to potential contamination. For the RCT to be conducted properly, officers would need to be randomly assigned into treatment and control groups. This design introduced the risk that officers wearing BWCs in the treatment group would interact with those without BWCs in the control group—a type of contact that could potentially alter control group members’ actions if they were aware that a BWC was present. Alternative sampling strategies were initially considered that would keep treatment and control officers separate from each other, but such alternatives were ultimately ruled out because they would violate the assumptions of an RCT and possibly introduce other spurious factors. The final decision, therefore, was to maintain the integrity of random assignment but to monitor for the possibility of contamination.⁵

Several technical issues also surfaced as the RCT was about to begin. One complication, for example, related to the completion of the BWC docking station infrastructure. LVMPD policy required that each officer place his or her BWC in a docking station at shift’s end. This process allows for the quick upload of video recordings, the preservation of video evidence, and the recharge of the BWC’s battery. From a practical standpoint, this meant that docking stations would need to be built at each of the eight area commands, otherwise officers would have to travel outside of their areas before and after their shifts to pick up and drop off the equipment. As the initial stages of the project were developing, however, it became apparent that there would only be sufficient time and funding to construct the docking station infrastructure at four of the eight area commands. As a result, the sampling frame of officers for the project was effectively cut in half, from approximately 1,100 to about 550. This still allowed for the necessary target sample of 400, but it raised some methodological questions about the selection of the four area commands and potential differences between officers in those commands versus officers from the areas that would not be selected.

Some of these issues were further complicated by both external and internal political concerns. During the early stages of the project, LVMPD was under significant community pressure to swiftly implement BWCs on officers. This pressure was especially felt in several communities where police–citizen relations had been strained over a period of many years. These influences from outside the organization had the effect of hastening the project timeline, but they also played a role in the selection of the four area commands where the BWCs would be implemented. Ultimately, the four area commands for the project were determined, at least in part, by the communities with the greatest concerns regarding police–citizen relations and the highest demand for the technology.

The more significant political challenges, however, came from within LVMPD itself. Prior to the project’s start, the executive staff of LVMPD became concerned that the police union would challenge the implementation of BWCs. Such a challenge would likely result in significant delays to the BWC program in general and to the start of the RCT specifically. Faced with community pressure to begin implementation, but concerned that union challenges would delay the program, LVMPD made the decision to make BWCs voluntary for current officers.⁶ This decision had a substantial impact on the sampling frame for the project: before random assignment to treatment and control groups could occur, volunteers willing to wear a BWC would first need to be recruited from the pool of approximately 550 officers. This raised methodological concerns in terms of statistical power (i.e., whether a sufficient number of officers would volunteer), especially since several influential officers within the agency were vocal about their opposition to BWCs on the grounds that video records could be used against police. It also raised concerns in terms of potential differences between officers who volunteer to wear BWCs versus those who do not.

Although unforeseen at the time, an additional administrative matter may have further complicated the recruitment of volunteers for the project. LVMPD’s Organizational Development Bureau (ODB) was the administrative entity responsible for the original pilot testing of the equipment and the development of BWC policy. When it was time for the project to begin, LVMPD placed ODB personnel in charge of BWC implementation since they were clearly the most knowledgeable of BWC technology, policy, and practice. A concern among officers may have developed, however, because at the time, ODB was a subunit of LVMPD’s Professional Standards Division—the same division that also administered the Internal Affairs Bureau (IAB). For officers who were already wary about volunteering to wear BWCs, the notion that Professional Standards personnel were involved in the process may have heightened concerns that BWC video could be used against officers.

Table 1 summarizes the various methodological, technological, political, and administrative challenges described in this section. Many of the concerns generated by these challenges were warranted. After the first round of recruitment in Spring 2014, only 82 officers volunteered to wear BWCs—far short of the target number of 400 subjects necessary for the RCT. Since half of these officers would be randomly assigned to the control group, this also meant that only 41 BWCs would be deployed in public—a number that LVMPD worried would be unsatisfactory to a community that was pressuring the agency to deploy all 200 BWCs purchased for the project.

Table 1.

Summary of BWC RCT Implementation Challenges and Resulting Concerns.

	Challenge	Concern(s)
Programmatic	Technical infrastructure only allows for the construction of BWC docking stations at four of the eight area commands	▪ Reduction of subject pool as the number of potential officers is cut in half ▪ Questions on whether officers in subject pool differ from those in other areas
	Faced with union concerns and community pressure, LVMPD chooses to make BWCs voluntary for officers	▪ Reduction of subject pool as officer concerns limit willingness to participate ▪ Questions on whether officers who volunteer differ from those who do not
	Administrative unit selected to implement BWC program was located in the Professional Standards Division	▪ Choice of unit heightens officer concerns, further limiting willingness to participate
Methodological	Due to requirements of randomization procedure, experimental (BWC) group is in contact with control group	▪ Potential contamination of treatment effect
Methodological	Data requirements necessitate the RCT to run for 1 year	▪ Potential for attrition problems

Note. BWC: body worn camera; RCT: randomized controlled trial.

Members of the research team who were present during the initial recruitment sessions documented reasons why officers did not volunteer (summarized in Table 2). Some did not volunteer simply because it was not required or because they did not want to bother with another piece of equipment. Many others, however, expressed concern that BWC footage could potentially be used against them. Interestingly, officers were not concerned (at least openly) about the appropriateness of their actions when dealing with citizens. They appeared more convinced that unscrupulous or vindictive supervisors would review their recordings in search of minor policy violations.

Table 2.

Summary of Reasons for Officer Refusal to Wear BWCs.

Reason	Example
“Wait and See” approach	“I’m not against it [the BWC] … I just want to see how the policy works for a while.”
Unconvinced of BWC benefits	“I have never had a problem with complaints against me. The camera is just something else that I would need to worry about.”
BWC video will be used against officers	“I don’t trust the administration with this.”

Note. BWC: body worn camera.

Confronting the Challenges

Programmatic Modifications

With the RCT design in jeopardy, LVMPD initiated a number of modifications that were designed to address technical, political, and administrative concerns, primarily by increasing the size of the subject pool. First, a technological solution was put into place allowing for subject recruitment from the four area commands that did not have full docking station infrastructures. This innovation could only accommodate a limited number of officers from each of these area commands, but it served the purpose of increasing the number of potential subject volunteers by 80.⁷ Importantly from a methodological standpoint, this solution also allowed for participation from all patrol area commands—not just those with the full equipment infrastructure.

Simultaneously, LVMPD addressed some internal challenges by revamping their BWC policy and their strategies for recruiting officers into the BWC program. The BWC policy was rewritten to better emphasize the value of BWCs for officers and to ease officer concerns regarding the use of video data for disciplinary purposes. For example, the language of the policy was altered to significantly limit the review of videos by supervisors and others within the organization. LVMPD also capitalized on several “success” stories from its limited BWC deployment. (Most of these stories involved cases where BWC video footage resulted in an officer’s exoneration after a citizen filed a false allegation of misconduct.) Recruitment into the BWC program may also have been helped by controversial events around the country, such as the shooting death of Michael Brown in Ferguson, MO, in Summer 2014; LVMPD argued that if the officer had a BWC in that case, a different narrative could have been established, and a great deal of turmoil could have been avoided.

Perhaps the most significant program modification, however, came in a decision to move the administrative portion of the BWC project from LVMPD’s Professional Standards Division to its Patrol Division. Since the area commands fall under the Patrol Division, it was reasoned that pressure could be placed on the executive staff of each area command to generate support for BWCs among officers. Much more so than personnel from Professional Standards, personnel from the area commands were in positions to convince officers of the value of BWCs, assure officers that video footage would not be used against them without cause, and encourage officers to volunteer for the BWC program.

Recruitment into the BWC program increased substantially after these changes were in place. While the first round of recruitment produced only 82 volunteers in Spring 2014, by the end of Summer 2014, 379 officers had volunteered. Furthermore, although some questions remain in terms of whether officers who volunteer are qualitatively different from those who do not, analyses demonstrated the equivalency of study participants and nonparticipants (as well as treatment and control officers) on key demographic and outcome variables (Table 3).⁸

Table 3.

LVMPD RCT Participants Versus Nonparticipants.

	RCT participants (n = 379)
	Control	Treatment	Nonparticipants (n = 992)
Gender
Male	91.5%	92.1%	90.1%
Female	8.5%	7.9%	9.9%
Race/Ethnicity
White	69.7%	73.3%	71.4%
Hispanic	15.4%	12.6%	14.7%
Black	9.6%	7.9%	6.4%
Asian/Other	5.3%	6.3%	7.6%
Age in years
Mean	37.5	36.3	35.8
Rank
Patrol officer 1	9.6%	9.4%	11.6%
Patrol officer 2	73.4%	77.0%	81.5%
Sergeant	17.0%	13.6%	7.0%*
Misconduct (per year)
Complaints (mean)	0.72	0.94	0.96
Allegations (mean)	2.27	2.65	2.81

Note. Difference of proportions z tests were used to assess observed differences in gender, race, and rank of officers in the treatment and control groups and those who did and did not participate in the RCT, respectively. Difference of means t tests were used to assess observed differences in age of and misconduct complaints against officers in the treatment and control groups and those who did and did not participate in the RCT, respectively.

p < .05.

Methodological Considerations

Several analyses were also performed to examine the major methodological concerns associated with the RCT design. Here we report on two of the most important process analyses for the LVMPD experiment: contamination between treatment and control officers, and attrition from the study sample.

Contamination

As mentioned earlier, one key concern regarding RCTs, especially those conducted in real-world (non-laboratory) settings, regards contamination effects. Contamination in randomized experiments refers to contact between individuals in treatment and control groups during the experimental period that threatens to weaken or dampen treatment effects because control group members might be influenced by the behaviors of individuals in the treatment group (Campbell & Stanley, 1963). In the context of the LVMPD BWC experiment, the concern was that patrol officers in the control group (non-BWC wearers) might come into contact with officers in the treatment group (BWC wearers), since it was likely that in some cases more than one officer would respond to any particular incident. If a treatment and control officer arrived at the same scene together, the fact that the treatment officer was wearing a BWC could have an effect on the behavior of the control officer.

Fortunately, we were able to utilize data from LVMPD’s computer-aided dispatch (CAD) system to monitor and assess the extent of contamination in the RCT. LVMPD data allowed us to determine, for each recorded call for service for 1 year (from March 2014 through February 2015),⁹ which officers responded to each call. We were also able to identify which of the responding officers were in the treatment and control groups, thus allowing us to estimate the percentage of calls for service that involved one or more treatment and control group officers. Importantly, this information can also be used in future impact evaluations to determine whether contaminated officers behaved differently from non-contaminated officers regarding key outcome measures (e.g., arrests, stops, complaints, use of force incidents).

From March 2014 to February 2015, the monthly number of CAD responses by LVMPD patrol officers ranged from a low of 43,291 calls to a high of 50,560 calls, representing an average of 42,537 calls per month. Correspondingly, the number of LVMPD officers responding to these calls for service ranged from a low of 92,726 to a high of 104,426, with an average 99,074 officers responding per month (Figure 1). These data indicate that it is relatively common for more than one officer to respond to the scene of an incident based on a call for service, which further justifies concerns about possible contamination effects.

Figure 1.

LVMPD CAD events and CAD officer responses.

Further analyses of the LVMPD CAD data revealed that contamination between treatment and control officers occurred approximately 20% of the time each month (from March 2014 to February 2015); contamination ranged from a low of 15.3% in March 2014 to a high of 20.9% in August 2014, with an average monthly contamination of 19.1% (Figure 2). The impact of this “moderate” contamination on outcome measures is not yet known. As noted earlier, future research that examines the impact evaluation of the LVMPD BWC experiment should identify and report on the influence of this contamination as it concerns the outcomes of the RCT.

Figure 2.

Percent contaminated control officer responses to CAD events.

Attrition

Attrition in an experimental study refers to the extent to which individuals in the study sample (in treatment and control groups) leave the study, thus lowering sample size and potentially effecting statistical power. For this RCT, factors affecting attrition over the course of the study period include the following: illness, injury, death, reassignment, or promotion. Analyses of attrition revealed that, despite these potential factors, attrition from the study sample was low. The power analysis conducted at the outset of the study indicated that the sample include at least 188 officers in the treatment and control groups.¹⁰ Following are the group totals with addition and subtraction data for each group:

The treatment group reached a high of 197 members in December 2014 and January 2015.

During the experimental time period, a total of 218 individuals were added to the treatment group and 34 individuals left the treatment group for various reasons.

The control group reached a high of 194 members in December 2014 and January 2015.

During the experimental time period, a total of 199 individuals were added to the control group and 15 individuals left the control group for various reasons.

The attrition rate for the study sample was 11.7% overall (16% for the treatment group; 8% for the control group). Although several reasons could account for the difference in attrition rates across the two groups, one factor concerns the nature of the BWC infrastructure. Officers in the treatment group who transferred to a different division during the course of the experiment could only keep the BWC if they transferred to an area command that supported the technology. Transfers to other divisions were less likely to impact control group officers who could remain in the experiment regardless of the BWC infrastructure.¹¹

Discussion

Table 4 presents a summary of the obstacles associated with the LVMPD BWC experiment along with the efforts made by LVMPD and the research team to overcome or better understand those obstacles. The LVMPD BWC experiment faced the combined challenge of both implementing an RCT in a large police organization and establishing a BWC program in a large agency. By instituting a number of programmatic changes to address various technical, political, and administrative concerns, the LVMPD was able to simultaneously implement its BWC program while supporting the RCT methodology. Most of these programmatic changes were designed to increase the potential number of officers who could wear a BWC or to increase officers’ comfort level with the technology. These efforts also served to satisfy external political pressures from a community that demanded the deployment of as many BWCs as possible.

Table 4.

Summary of BWC RCT Implementation Concerns and Resolutions.

	Challenge/concern	Resolution(s)
Programmatic	Original technical infrastructure allows for BWC docking stations at four of the eight area commands, thus reducing subject pool and creating questions on whether officers in subject pool differ from those in other areas	▪ Technical innovations allow for limited recruitment from non-infrastructure area commands
	BWCs are made voluntary for officers; officer concerns limit willingness to participate, thus reducing subject pool and creating questions on whether officers who volunteer differ from those who do not	▪ Policy changes address officer concerns ▪ “Success” stories where BWC videos exonerate officers aid in recruitment ▪ Events from around the United States are used to demonstrate value of BWCs to officers ▪ Analyses demonstrate no differences between volunteers and non-volunteers on key demographic and outcome variables
	Original administrative unit selected to implement BWC program heightens officer concerns about BWCs, limiting willingness to volunteer	▪ Administrative unit shifted to Patrol Division where officer concerns over BWCs are better addressed and volunteerism can be encouraged
Methodological	Due to requirements of randomization procedure, the experimental (BWC) group is in contact with the control group, thus generating concern over contamination (i.e., the control group could be influenced by the experimental treatment)	▪ Analyses indicate that treatment and control officers are in contact on approximately 20% of calls for service ▪ The impact of this ‘moderate’ contamination effect is unknown, but future analyses should account for the effect
Methodological	Length of RCT generates concern over attrition	▪ Analyses indicate attrition rate of 16% for treatment group and 8% for the control group. ▪ Differential attrition can be explained by BWC infrastructure

Note. BWC: body worn camera; RCT: randomized controlled trial.

The length of the experiment and the nature of the RCT introduced additional methodological concerns, mostly in the form of potential attrition and contamination. Analyses of attrition indicate that officers in the treatment group dropped out of the experiment at a slightly higher rate than those in the control group, but much of this difference can be explained by the BWC infrastructure rather than the subjects’ conscious decisions to discontinue. Methodological questions still remain, however, regarding a possible contamination effect. To maintain the integrity of the experimental conditions, officers in the treatment and control groups could not be isolated from each other. The analyses reveal that control and treatment officers responded to the same calls about 20% of the time, introducing the possibility that the treatment effect (BWCs) influenced control group officers. Future analyses will need to consider whether this interaction between treatment and control officers had a significant effect on experimental outcomes.

Interestingly, the well-known Rialto (CA) BWC randomized experiment also experienced possible treatment contamination effects, but due to the randomization of BWCs by shift rather than by individual officer (Ariel, Farrar, & Sutherland, 2015). In the Rialto RCT, the same officers participated in treatment (BWC on during shift) and control conditions (no-BWC during shift). As such, it was possible that participating officers “carried over” the treatment effect into control shifts. While the evaluation did still find significant reductions in citizen complaints and use-of-force incidents during treatment shifts relative to control shifts, Ariel et al. (2015) also observed reductions in these outcome measures during the control shifts, which suggest possible contamination. The RCT design discussed in the current article attempts to minimize these kinds of contamination effects by using different officers in control and treatment groups. Ideally, the RCT would have also separated treatment and control officers into different policing areas to minimize interactions further. Unfortunately, this was not possible due to our reliance on volunteer officers to comprise treatment and control groups.

Some aspects of the LVMPD experience will not apply to agencies seeking to implement a BWC program or conduct research on BWCs, but other aspects will be informative, and there are lessons learned for all police agencies. From a programmatic perspective, for example, many departments mandate that officers wear BWCs, therefore issues associated with officer volunteerism will be less applicable. Volunteerism aside, however, the challenge of motivating officers to accept cameras—and to follow camera policy—applies more generally, and LVMPD’s success at motivating officers to volunteer for the BWC experiment should be instructive.

Furthermore, many agencies and researchers will not opt for an RCT to evaluate a BWC program because the design is deemed too difficult, impractical, or unnecessary given alternative research strategies. To be sure, RCTs with large police agencies in non-laboratory settings can be a challenge to implement and, as this article demonstrates, may have their limitations.¹² On this note, we suggest, with respect and understanding for the difficulties that RCTs present, that the utilization of a variety of rigorous evaluation designs is important for moving the field forward regarding the evidence of the impact of BWCs on police and civilians alike. Police departments interested in contributing to police science and to the body of evidence regarding what works in terms of both police and public safety should consider experimental designs (quasi-experiments and randomized trials) in their plans to study the impact of this technology.

The LVMPD experience demonstrates a number of key challenges in terms of implementing and studying a BWC program. Agencies are likely to encounter numerous technical, political (external and internal), and administrative concerns while adopting BWCs and are well advised to consult the experiences of other, similarly situated agencies. As policing moves forward into the 21st century, BWCs will likely play some role regarding transparency, accountability, and the enhancement of public trust in the police. We encourage police agencies and researchers to continue studying the impacts of BWCs, to study them with rigorous research designs, and to pay close attention to the process and administrative aspects of BWC implementation in their research.

Footnotes

Acknowledgment

The authors would like to thank the Las Vegas Metropolitan Police Department and, in particular, the staff of the Body Camera Unit, for their assistance and cooperation in the preparation of this article.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This project was supported by Award No. 2013-IJ-CX-0016, awarded by the National Institute of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect those of the Department of Justice or of the Las Vegas Metropolitan Police Department.

Notes

Author Biographies

William H. Sousa is the director of the Center for Crime and Justice Policy and an associate professor in the Department of Criminal Justice at the University of Nevada, Las Vegas. The focus of his research is on crime and disorder reduction policies implemented by police agencies. His current projects involve police order-maintenance practices, policing technologies, and community crime prevention in Las Vegas neighborhoods. He received his B.A. from Stonehill College (Easton, MA), his M.S. from Northeastern University, and his Ph.D. in Criminal Justice from Rutgers University.

James R. Coldren, Jr. serves as the managing director for Justice Programs at CNA, in the Institute for Public Research. In this capacity he oversees national research and technical assistance projects pertaining to police use of force, officer involved shootings, police-community relations, policing innovation and evidence based practices, and justice system reform initiatives. Prior to his work at CNA, he served as the director of the Office of Sponsored Programs and Research and as the program coordinator for the Interdisciplinary Leadership Doctorate and Criminal Justice MA programs at Governors State University in Illinois. He holds a Bachelor's Degree in Sociology from Rutgers University, and a Masters and Doctorate in Sociology from the University of Chicago. He attained his “Masters” certificate in Leadership from Rapport Leadership International and is a 2005 Leadership Greater Chicago Fellow.

Denise Rodriguez is a research scientist at CNA where she currently manages over $4 million in grants, leads several project teams, and oversees 15 team members. While at CNA, she has assessed police policy and procedures, reconstructed police critical incidents and large-scale events, developed use of force policies, managed research on collaborative reform initiatives, and produced law enforcement specific after-action reports for a number of federal and local-level law enforcement agencies. She has over seven years of experience working in the criminal justice and law enforcement field, and she holds a Master of Arts degree in Forensic Psychology and a Bachelor of Arts degree in Criminal Justice.

Anthony A. Braga is a distinguished professor and director of the School of Criminology and Criminal Justice at Northeastern University. Braga is a fellow of the American Society of Criminology. He is also a fellow and past president of the Academy of Experimental Criminology and the 2014 recipient of its Joan McCord Award. His research focuses on working with criminal justice agencies to develop crime-prevention strategies to deal with urban problems such as gang violence, illegal gun markets, and violent crime hot spots. He received his M.P.A. from Harvard University and his Ph.D. in criminal justice from Rutgers University.

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