A study published this year traces policing outcomes in Las Vegas between Sept 2014 and Oct 2015, comparing the conduct of 200 officers who wore bodycams and 200 who did not.
The study, conducted for the National Institute of Justice by UNLV and the Center for Naval Analyses, found that bodycams correlated with a 37% reduction in use of force incidents, a 30% reduction in public complaints against the police, and saved $4 million/year in administrative costs associated with police use of force.
Officers who wore the cameras were more likely to make arrests, and less likely to issue citations. The officers who wore the camera did not report a subjective change in their behavior, despite the marked differences in the outcomes.
According to the study, camera footage has been used to close more than 500 internal investigations, with 462 of those exonerating the officer. The remaining cases resulted in disciplinary actions, including the termination of one officer. While it still seems odd such a high percentage of officers would be cleared, the fact remains officers' fears of managerial gotcha tactics are unfounded.
The addition of body cameras has another positive effect, one that goes straight to the bottom line. With footage available for use in internal investigations, the cameras' initial cost is far outweighed by net savings for taxpayers. From the study summary [PDF]:
When considering the investigator’s modified hourly wage and hours spent investigating a complaint of misconduct, considerable cost savings are realized when BWC video is available. Rather than a combined 91 hours of investigative time costing $6,776 without BWCs, the estimate is slightly over 7 hours of investigative time costing $554, for a difference of over $6,200 per complaint of misconduct.
The Benefits of Body - Worn Cameras: new findings from a randomized controlled trial at the Las Vegas Metropolitan Police Department [Anthony Braga , James R. Coldren, Jr., William Sousa, Denise Rodriguez, and Omer Alper/National Institute of Justice]