As police work is increasingly captured on camera and scrutinized by the public, from traffic stops to a BART police officer's killing of Oscar Grant, many law enforcement agencies are asking the same question.

Why not control the cameras ourselves?

Around the Bay Area, police departments are studying what would be a profound cultural shift in law enforcement: outfitting all cops with wearable cameras to record stops, arrests, sobriety tests and interviews.

The practice, meant to gather evidence and provide a video record if misconduct allegations arise, is a step forward from dashboard cameras that have become common in cruisers and audio recorders that many officers strap to their belts.

Police departments in several cities, including Union City, Campbell and Brentwood, recently bought batches of the body cameras. Officials in many other cities see the trend as unstoppable.

"In the future, officers will not hit the streets without a camera," said Sgt. Ronnie Lopez of the San Jose Police Department, where officers recently tested a set of 18 over-the-ear cameras made by Taser International Inc. of Scottsdale, Ariz., the same company that makes the electronic shock guns.

"We live in a YouTube society where people have the ability to record us," Lopez said. "We firmly believe officers do the right things for the right reasons, and this is a way to show our side."

The cameras may present a rare opportunity for accord between police commanders and police watchdogs.

John Burris - an attorney who specializes in police misconduct cases and is suing BART over the killing of Grant, an episode filmed by five train riders - said the cameras could compel officers to be more professional.

"Nothing looks uglier on camera," Burris said, "than the gratuitous use of force on a person."

Potential problems

However, as with many powerful technologies that police have adopted, the cameras bring some thorny issues - concerns that have arisen inside and outside law enforcement circles.

The cameras "can be an important tool for promoting police accountability and integrity as long as they are used in a proper way," said Kelli Evans, associate director of the American Civil Liberties Union of Northern California.

Evans, who was appointed by a federal judge to monitor reforms of the Oakland Police Department, said the presence of the cameras could de-escalate tense situations, while supervisors could use footage as a training tool and a method of auditing officers' conduct.

However, she said, departments must set clear rules governing when officers turn the cameras on and how footage is stored, to make sure it is not altered and is available if someone makes a complaint.

Rules for cops

In Campbell, Union City and Brentwood, officials said, officers have discretion over when they turn on their cameras. But they cannot alter or delete footage.

Campbell officials said they keep all footage for at least a year. Brentwood officials said the video is kept for at least three years. In Union City, officials said, video that is considered to be evidence in a case is kept permanently, but more routine footage is discarded after a day.

George Beattie, the president of San Jose's police union, has a different concern. He said officers who wear cameras may be hesitant to use force, such as kicks and baton blows, in situations that demand it.

"The officer may not think, 'Am I doing the right thing?' but instead, 'How is it going to be viewed by somebody else?' " said Beattie, a police lieutenant. "On paper, it sounds like a great idea, but there are definitely some drawbacks to it - drawbacks that can have life-ending consequences."

Not inexpensive

Then there is the price. The high-definition Taser Axon cameras that San Jose borrowed for a couple of months cost $1,700 each, plus a monthly $99-per-camera fee to a third-party firm that manages the footage, Lopez said.

The Axon has three parts: the camera, a microphone worn on the shirt and a DVR box for the belt. When an officer presses a button to start recording, Lopez said, the prior 30 seconds are captured as well because the camera is always on.

Union City, meanwhile, recently paid nearly $150,000 for 85 cameras made by Vievu of Seattle, plus the computer infrastructure to support them and store footage. Oakland police are now trying out 20 of the same cameras.

Union City police Lt. Kelly Musgrove said it was too early to assess the value of the cameras, which are also available to animal control and parking enforcement officers.

"I know my officers are using it, especially for victim interviews, field sobriety tests and suspect interviews," Musgrove said. "Some things you just can't describe in a police report."

Camera is 'impartial'

He said the cameras aid in prosecuting criminals and handling complaints against officers.

"If someone has an issue with one of my officers," Musgrove said, "the camera is very impartial."

In Brentwood, George Aguirre and two other traffic officers wear Vievu cameras on their chests. It's part of a larger devotion to video in the city, where cameras are in police cars and inside every officer's Taser shock weapon. Turn on the Taser, and the camera rolls.

Aguirre's chest camera - which can store four hours of footage - clips onto his uniform and is roughly the size of a pager or garage door opener. To start recording, he simply slides down a lens cover. Most drivers, he said, don't even notice.

"I'd rather you see what I did than hear accusations," said Aguirre, who does traffic enforcement on a motorcycle and commercial vehicle enforcement in a truck. "When you do everything you're supposed to do and someone challenges you, there's nothing better than being able to show the video to them or my supervisors."

During a crash investigation, Aguirre said, he turns on the camera not only to record the statements of witnesses and suspects, but to capture their facial expressions and gestures.

And if a traffic stop turns confrontational, Aguirre often points at his camera.

"I will make a point of saying, 'Sir, just to let you know, you're being recorded,' " he said. "That will change their tone."