Body-worn cameras are increasingly being adopted by law enforcement across the country, offering a potential antidote to police brutality but also raising fears about mass surveillance and questions about how the footage is used.
The rush to implement body-cam technology comes amid public outcry over police shootings, such as the case of Keith Lamont Scott in Charlotte, North Carolina. The incident was caught on camera but prosecutors announced Wednesday that the cop who fired the fatal shots "acted lawfully."
The parking lot incident was captured on a police body cam — as well as by the Scott's wife on her cellphone. The footage sparked days of protests.
Some human-rights campaigners oppose body-worn cameras, saying that they raise issues surrounding privacy, particularly where minority communities are concerned or during sensitive situations such as domestic violence calls.
They warn that body cams provide only sliver of what happened and that footage can sometimes be misleading because it's not showing the full picture.
Critics argue that adding facial recognition technology to the equation is yet another chunk of data that's being collected on individuals, regardless of whether they have a criminal record. This information could be used to track the movements and personal associations of people, potentially discouraging some from attending lawful protests, for example.
Other non-profit groups, however, believe that with the right legislation, body-worn cameras could help improve police relations with the public. A 12-month study by Britain's University of Cambridge in 2014 found that such technology reduced the use of police force and the amount of complaints filed by citizens in Rialto, California.
"Police body cameras onto themselves are neither a good nor a bad thing," the American Civil Liberties Union's Chad Marlow said. "It's all dictated by the policy that govern their use. If you have the right policies in place, body cams can be an important tool to help promote police transparency and accountability, while at the same time protecting privacy. If the wrong policy is in place, they turn into nothing more than a mass surveillance and police propaganda tool."
"On-officer recording systems" are fitted onto uniforms, intended to record daily interactions with the public in an unbiased manner, particularly when force is used.
Demands for accountability due to racial discrimination and profiling within police forces prompted a New York judge in 2013 order a body cam pilot program after deeming the state's stop-and-frisk policy unconstitutional.
Social unrest triggered by the 2014 shooting of Michael Brown in Ferguson, Missouri, resulted in such programs spreading nationwide — assisted by $20 million of initial funding from the Justice Department.
However, no privacy or other requirements were mandated in order to acquire financing.
That has created problems. In Albuquerque, New Mexico, officers independently chose whether or not to delete body-worn camera footage at the end of their shifts.
In Charlotte, North Carolina, a new law passed in the wake of Scott's shooting makes it difficult for the public to view any police video. That decision triggered even more protests.
But in Chicago, a police officer who failed to record the shooting of 18-year-old Paul O'Neal, despite wearing a body camera at the time, was placed under administrative leave.
Body cams worn by police officers in Baton Rouge, Louisiana, also failed to capture footage during the shooting of Alton Sterling. They blame on the equipment's manufacturer.
"If police use their body cameras to capture footage on everything that they experience in the day, but the police get to determine solely what the public gets to see and they have the ability to only release videos that show them in the best light or promotes their perspective, that's the definition of propaganda," Marlow added.
Colorado's Parker Police Department, a mid-size agency serving a community of approximately 50,000, started using the technology in Sept. 2015.
"You have an additional piece of evidence for the officers, which helps substantiate the report that they're writing and the information that they're gathering," said Chris Peters, a commander in the department's Professional Standards Unit. "So instead of just having written documentation of what the scene looked like, you have a video perspective of what the officer was seeing as well. If someone complains about an officer or about something that occurred, for example, rather than it being a member of the public's word versus an officer's word, you now have this addition of a camera that's capturing audio and visual, giving you an additional perspective that is completely third party."
Body-cam policies being used at both the local and state levels vary widely with some forces have been more transparent than others.
In August, the civil liberty umbrella organization Leadership Conference on Civil and Human Rights, which includes the ACLU as a member, and the technology impact assessment group Upturn noted in a report that 43 of the country's 68 "major city" departments were using body-worn cameras with policies in place.
However, Pittsburgh, Detroit and Baton Rouge, all widely known to have at least tested body-worn cameras, had no policy information publicly available.
"Our main findings with the report is that with body-worn cameras accountability doesn't come automatically," said Harlan Yu, principal technologist at Upturn. "That's the bottom line. These are tools that are completely powerful and that are used by officers to point at the community and not inward at the officers. If body-worn cameras are owned and operated by police departments, I think that there are legitimate fears that they will just be used as a new surveillance system gathering evidence about crimes that will be used to over-police and over-prosecute people of color."
While companies like Taser have announced plans to begin using facial-recognition software in their body-worn cameras, Colorado's Parker Police Department have prohibited its use in their camera policy.
"The intent of this is not to collect surveillance about the public," Peters told NBC News. "The sole purpose of these cameras is to add an additional layer of what occurred at that particular incident, not to store people's whereabouts."
The Parker Police Department's use of body-worn cameras has been praised by the ACLU.
When a police officer there is dispatched on an "enforcement action" they turn their camera on, and it runs throughout a police response, investigation or arrest, Peters said. However, footage is not captured during a typical foot patrol.
Monthly audits of randomly selected videos are also conducted by a committee of "sworn and civilian members" to see whether the body cams are being used appropriately.
Videos are kept by the Parker Police Department for approximately 18 months, the length of time allowed for an individual to file a complaint or lawsuit. Videos involving use of force or shooting are kept for at least 3 years.
Upturn's Yu said it was important for forces to take on board are "a lot of tricky policy decisions to be made" around the technology.
He added: "I think departments are realizing that in order to implement body-worn cameras it's not just about buying cameras and putting them on their officers and getting them out in the field."