WASHINGTON — Civil rights activists and some police chiefs are warning that the Obama administration’s proposal to help local police departments buy 50,000 body cameras must come with firm rules on how to use the equipment.

They say that without proper oversight to address potential misuse, such as when police turn off their cameras during brutal acts, the wide deployment of the equipment could undermine efforts to build trust in police departments across the country.

Last week, Barack Obama announced a $75 million plan to help police departments buy body cameras after a state grand jury decided not to indict a White officer in Ferguson, Missouri, for the shooting death of an unarmed Black teen, sparking protests and conversations about excessive force and racial bias in policing.

Obama’s plan, which requires congressional approval, calls for departments to undergo training, receive guidance on best practices from the Department of Justice and submit a plan of use for approval.

The department is still working out how thorough those measures must be.

However, a Justice Department official told Reuters that should police violate the terms of such a plan, enforcement will fall to local and state authorities.

Civil rights and civil liberties advocates are wary of the lack of a federal enforcement plan.

“You must have an accountability mechanism,” said Barbara Arnwine, executive director of the Lawyers’ Committee on Civil Rights. “If you have a department that has a bad record and is bad at following through on discipline, then body cameras are meaningless.”

Police Chief Michael Chitwood, who has been using body cameras in his department in Daytona Beach, Florida, since 2010, said his experience has shown the need for strong oversight.

He said he fired an officer earlier this year for turning off his camera during a brutal beating of a woman, which violated a policy he had established.

Chitwood said the Justice Department should issue strong guidelines that could override local politics and union power that can tarnish policies.

“The Department of Justice has a huge role in it because different jurisdictions have different internal power structures. Any policy that a commissioner comes up with, that (police) union is going to use its power to stop the cameras unless they get the policy that they want,” he said.

Not all police chiefs share his view. “I wouldn’t want the federal government dictating how I use my cameras,” said Ken Miller, police chief in Greenville, South Carolina and formerly chief in Greensboro, North Carolina, where he used body cameras. “Every community has their own issues and their own dynamics.”

It’s also not clear how a federal enforcement mechanism could work. Grants to purchase equipment would be provided by the Justice Department’s Office of Justice Programs, which has little authority beyond ensuring the specified equipment is purchased.

The federal government has come under attack for lax oversight of a separate Pentagon program that gives unused military gear, including heavily armored vehicles and machine guns, to local police departments.