A D.C. police officer wears a body-worn camera mounted on her glasses. EPA/MICHAEL REYNOLDS

President Obama wants to help local police departments equip their officers with cameras to record interactions with the public. The White House's proposal, announced Monday along with several other law-enforcement initiatives, is the latest indicator of a technological shift in policing that civil rights advocates hope will prevent incidents like the shooting of Michael Brown in Ferguson, Mo. in August.

"Within the next five years or so, body-worn cameras will be as ubiquitous in the world of policing as handcuffs, the police radio, the gun," said Jim Bueermann, president of the Police Foundation in Washington and a former chief of police in Redlands, Calif.

Bueermann argues when police wear cameras, they're less likely to use force, and that members of the community place greater trust in police. He also said that most police chiefs would buy the cameras for their departments if they weren't so expensive. A typical unit can cost as much as $1,000, according to a report from the Department of Justice.

Obama's proposal would partially solve that problem by reimbursing localities for half the cost of buying and storing the cameras. The program, which would require a congressional appropriation, would cost $75 million over three years would contribute to the purchase of roughly 50,000 devices.

By comparison, there were not quite 700,000 police officers in the United States in 2011, according to the FBI. Taser International, one of the main suppliers of the cameras, has sold about 30,000 of them, said a spokeswoman, Sydney Siegmeth. She also said in the quarter following Brown's death, the number of police departments in major cities testing Taser's cameras tripled to 35.

Available evidence suggests that cameras do change interactions between police and the public. When the police department in Rialto, Calif. conducted a trial, assigning cameras to half its 54 officers at random, the use of force declined by 60 percent. The department's study also found no incidents in which officers wearing cameras used force unless their devices had recorded someone threatening them. Complaints filed against Rialto officers dropped to just three during the year of the study from 24 the previous year. Another study in Mesa, Ariz. found similar results.

As the Justice report noted, it isn't clear whether these changes are a result of citizens treating officers with more respect when they were wearing cameras, or of officers using force more sparingly, knowing that their actions were being recorded. Whatever the reason, the cameras seem to make both officers and members of the public safer.

That said, the cameras also raise difficult questions about privacy, both for officers and the people they meet. Privacy would be a real concern for officers wearing cameras while responding to reports of domestic violence, for example.

Dashboard cameras are common in many police vehicles, and the footage is generally public record, said Trevor Burrus of the libertarian Cato Institute. Yet police leave those cameras in the car when they enter someone's home. Burrus supports the idea of more and more police wearing cameras, but he predicted that what kinds of footage qualify as public record will be a question that the courts have to decide.

Then there's the awkwardness for police chiefs of asking their employees to wear a camera throughout their workday, Bueermann said. But he added that officers tend to like the cameras once they realize that the footage will support them if members of the public complain about them without reason.

Bueermann sees the administration's proposal as a start, but that cameras won't immediately solve the problems of police departments that have lost the trust of their communities.

"The problems go much deeper than technology, but this is the first thing that needs to be done to move forward," he said.

Whether Obama's proposal has a chance on the Hill remains to be seen, but there is some support among lawmakers for encouraging police to wear body cameras. After Brown's death, Sen. Claire McCaskill (D-Mo.) proposed making cameras mandatory for any police agency receiving federal funds.

Correction: An early version of this post misspelled the name of the president of the Police Foundation. It is Bueermann, not Buerrmann.