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.
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.
Such video "sometimes captures people at the worst moments of their lives," American Civil Liberties Union senior policy analyst Jay Stanley said.
"You don't want to see videos of that uploaded to the Internet for titillation and gawking," he said.
Video from dashboard cameras in police cars, a more widely used technology, has long been exploited for entertainment purposes. Internet users have posted dash-cam videos of arrests of naked women to YouTube, and TMZ sometimes obtains police videos of athletes and celebrities during minor or embarrassing traffic stops, turning officers into unwitting paparazzi.
Officers wearing body cameras could extend that public eye into living rooms or bedrooms, should a call require them to enter a private home.
Faced with the challenge of striking a balance between transparency for police and privacy for citizens, U.S. law enforcement agencies have not adopted a uniform policy for body cameras, which come in various sizes and can be worn on shoulders, glasses and lapels.
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.)
"Unfortunately, you're seeing a lot of departments just sticking cameras on their officers without thinking through the policies very well," says Stanley, who supports police use of body cameras, but only with careful regulation.
Some observers have raised the possibility that such cameras would not only be used to review officer behavior — to potentially overbearing levels, if used to crack down on minor disciplinary infractions — but someday also may be used with facial-recognition technology the way many departments already use license-plate scanners.
"Are these cameras going to eventually be hooked up to these systems where cops can scan the street and pick out anybody's face or anybody's car to see if they have an outstanding warrant?" asked Trevor Timm, executive director of the Freedom of the Press Foundation and an analyst of surveillance and transparency issues. "I think a lot of these communities that have problems with police will have problems with that, too."
In 2014, video evidence has been a powerful public arbiter of behavior. In case after case, the emergence of video has tilted public sentiment over highly fraught encounters that often last only a few moments.
But in Ferguson, Mo., where a white police officer shot and killed a black, unarmed 18-year-old man on Aug. 9, no definitive video has surfaced.
The police department, besieged by criticism and skepticism from Ferguson residents, has since added body cameras for its officers in hope of rebuilding its credibility, and many other U.S. police departments may not be far behind.
"I think it's inevitable," Greenville, N.C., Police Chief Hassan Aden said. "These cameras are going to change the way that police equip their officers.
"In the future, you're going to get your car, your gun, your badge, your radio — and your camera. It's going to add to police legitimacy everywhere, and it's going to create a better rapport with the public," he said.
A 92-page policy report released this month by the U.S. Department of Justice and the Police Executive Research Forum suggested that "body-worn cameras help police departments ensure events are also captured from an officer's perspective."
Police chiefs who support body-cam technology say that both officers and citizens behave better while being recorded and that with the cameras, complaints against officers have declined, with video often — but not always — supporting the officers' sides of the story.
Aden, who helped compile the federally commissioned report, told The Times that the number of sustained complaints against his officers had gone down.
"But we've found other [complaints] that really have been valid," he said. "We've actually had terminations because of video."
Grand Junction, Colo., Police Chief John Camper, who has been considering body cameras, remains torn.
"In this YouTube world and reality-TV world, everybody thinks cameras are the end-all," Camper said. But he worries that body cameras, in addition to not capturing everything, could also capture too much.
"We want people to feel free to talk to a police officer as a trusted confidant, and if we sit here and have a camera mounted on a lapel — are you really going to want to talk about a problem with a marriage or with a child or a sexual assault if I have a camera pointed at you?" Camper said.
For that reason, experts and privacy advocates have encouraged departments to adopt policies that include allowing victims and reluctant witnesses to be filmed only with their consent.
The newly released federal report also suggests that departments should clearly outline policies for how long they will keep video recordings before deletion; 60- or 90-day holding periods are common, unless the video is used as criminal evidence or has been flagged in a complaint.
The extra layer of scrutiny is also a labor concern for some police unions, who are worried that a tool intended for transparency will be diverted for workforce surveillance.
One notable skeptic of body cameras is Missouri state Rep. Jeff Roorda, business manager for the St. Louis Police Officers' Assn. He is also vice president of a police union charity providing support for Officer Darren Wilson, who confronted and shot Michael Brown in Ferguson. Roorda said St. Louis officers' experiences with dashboard cameras have made them skeptical.
"Instead of the cameras being there to protect the officers, they get disciplined for petty stuff constantly — for violating the uniform code, or rolling through a stop sign for an urgent call, or for not turning the camera on," Roorda said. "That's one of the hottest issues for my guys. They're tired of the nitpicking, and that's what the cameras have been used to do."