Scores of law enforcement agencies already use body-worn cameras, and calls for more have only grown across the U.S. after recent cases involving use of force have pitted the word of police officers against angry residents, reports the L.A. Times.

The Los Angeles County Sheriff's Department and the Los Angeles Police Department, along with police in New York, Chicago, and Washington, have launched pilot programs to test cameras for wider deployment.

But equipping police with such devices also raises new and unsettled issues over privacy at a time when many Americans have been critical of the kind of powerful government surveillance measures that technology has made possible.

For many departments, questions remain about when officers should be allowed to turn off such cameras — especially in cases involving domestic violence or rape victims — and the extent to which video could be made public.

A recent federal survey of 63 law enforcement agencies using body cameras said nearly a third of the agencies had no written policy on the devices. (It is not known how many agencies overall currently use body cameras.)