Las Vegas police officer Richard Scavone is facing a misdemeanor battery charge after body camera footage revealed that he had, according to Undersheriff Kevin McMahill, used excessive and unreasonable force while arresting a woman for loitering for prostitution in January.

Scavone’s lawyer said that his client, who is suspended with pay, was one of the 400 volunteers taking part in the Las Vegas Metropolitan Police Department’s body camera study. Footage of the incident has not been released, as it is being used in the ongoing investigations conducted by the Clark County District Attorney and the Las Vegas Metropolitan Police Department.

This is not the first time that police body cameras have captured alleged excessive force. In January, prosecutors in Albuquerque, New Mexico said that they would be pursuing murder charges against two police officers who in March 2014 shot and killed James Boyd, a homeless paranoid schizophrenic camping in the Sandia Mountains. The killing was filmed by a helmet camera worn by one of the officers at the scene. Speaking about the case, Bernalillo County District Attorney Kari Brandenburg said, “We have evidence in this case to establish probable cause we didn’t have in other cases.”

Both the Las Vegas and Albuquerque incidents highlight that body cameras are valuable in providing extra transparency and accountability but are not a panacea for allegations of police misconduct.

Very few studies have been conducted that examine the effects body cameras have on police behavior. One of the most referenced studies on police body cameras, which took place in Rialto, California from February 2012 to February 2013, did find that “use-of-force” incidents and citizen complaints against officers dropped dramatically compared to previous years (see chart from the study below).

Another police body camera study, which took place in Mesa, Arizona from October 2012 to October 2013, also found that officers wearing the Axon Flex cameras received fewer complaints than in the 12 months prior to the evaluation period. In the chart below IA refers to “IA Pro” and Blue Team refers to incident recording software used by Mesa PD. 

The findings in the Mesa and Rialto studies suggest that body cameras may have a role in reducing complaints against police officers, but it remains unclear if this is because the cameras are prompting police officers to significantly change their behavior or if they are changing citizen behavior. It is worth considering not only that citizens may behave better when they know they are being filmed but that the cameras remove an incentive for citizens to file frivolous complaints. In addition, other factors such as changes in department policy or personnel may have an impact on officer behavior. More research is needed in order to definitively determine whether police body cameras have some “civilizing effect” on officers and citizens.

Nonetheless, as events in Las Vegas and Albuquerque have shown, police body cameras provide welcome evidence in police misconduct investigations. Body cameras may play a role in improving police officers’ and citizens’ behavior, but reforms to use-of-force policy and training need to be implemented in addition to body camera deployment if police conduct is to significantly change for the better.

*Update: The chart for the Mesa study used above is a projected analysis from an August 2013 report. The chart from the December 2013 report is below. It shows a ‑40 percent change in complaints and Blue Team inquires, rather than the projected ‑60 percent.