Dozens of Vancouver police officers are now recording their interactions on body-worn cameras in a pilot project the department says is aimed at improving public trust.

Deputy Chief Howard Chow announced 85 officers in the traffic section, and those who work in the downtown core and in East Vancouver will begin patrolling with chest-mounted cameras.

The department says in a statement that officers are expected to activate their cameras as soon as it's safe and when there's a reasonable belief that there will be a use of force or violent behaviour.

After extensive community consultation, Chow says they believe they've reached a balance that protects peoples' rights and privacy, while enhancing public trust.

A coroners' jury in the 2015 police beating death of Myles Gray recommended last May that Vancouver police expedite its plans to use body-worn cameras for all patrol officers.

The statement says the results of the pilot project will guide the department in developing a broader camera policy for all its officers.

Chow says the cameras launched Thursday are about trust and continuing to deliver the best service to residents.

"We are confident that we are hiring excellent men and women to do a very challenging job. However, if this tool helps to reassure and strengthen public confidence and trust, then it's an important step worth taking."

The department says officers who activate their camera will inform a person they are being recorded as soon as possible, unless doing so could jeopardize the safety of police or the public.

It says officers aren't required to have their cameras on all the time if they aren't responding to a specific incident or interaction with a member of the public.

Christopher Schneider, a sociology professor at Brandon University and author of the book Policing and Social Media: Social Control in an Era of New Media, said the evidence to date doesn't necessarily support claims that body-worn cameras will bring accountability and transparency, or restore trust in policing.

"I'm not necessarily opposed to body-worn cameras," he told CBC's On The Coast. "We need to make sure they're doing what it is people say they're doing."

Schneider said researchers have tested whether there's a change in police use of force when officers are wearing cameras, and in some circumstances the use of force actually increases, while in others there's no statistically significant difference.

He said the ability to turn cameras on and off complicates some of the claims about potential benefits.

"It's unclear how we can hold police officers accountable for their conduct, say if there's a police brutality complaint … if the officer has used their discretion to switch their camera off," Schneider said.

He said strict policies should be implemented to ensure body-worn cameras produce the accountability and transparency that have been promised.

In Schneider's mind, that would include serious consequences for officers who turn their cameras off before interacting with the public, measures preventing police from reviewing their camera's footage before giving statements during a misconduct investigation, and mechanisms that would allow members of the public to access footage of their interactions with police without requiring freedom of information requests.