The Canadian Civil Liberties Association is concerned about Thunder Bay police wearing cameras on their uniforms.

Police say audio and video recordings will hold them accountable for their actions and increase public confidence, but a spokesperson with the CCLA says that only works if the cameras are on all the time.

"What you don't want is the officer turns on the camera and you see the citizen being impolite ... [when] the interactions prior to the camera being turned on was really more the police officer that was interacting in a negative fashion with the citizen,” said Nathalie Des Rosiers, general counsel with the CCLA.

Police said video files are too big to keep the cameras running all the time.

Thunder Bay defence lawyer Neil McCartney says it could be problematic if police don't keep everything they record while using body cameras, particularly when it comes to questions from the court. (Supplied)

Storing everything officers record would likewise not be possible because of the large files, according to police. Thunder Bay defence lawyer Neil McCartney said that could be a problem if the video is used later in court.

“When the defence receives that material, they may ... decide 'hold on, I didn't get everything that's relevant to this investigation. Where's the important minute 23 or where's the hour that followed?'”

Objective, unbiased account

But Thunder Bay Police inspector Alan McKenzie said “not every contact with the public will be necessary to video and it's up to the discretion of the officer [to record the interaction].”

The move to body cameras comes on the heels of city police deciding to install video cameras in 20 of its police cars.

The force is also dealing with a few high-profile public complaints recently made against it.

McKenzie said police have tried out the cameras on three shifts so far as a pilot project, and notified citizens they were being recorded.

He noted the cameras provide an objective, unbiased account of interactions between police and citizens and also allow officers to instantly play back the footage to help them recall an event for their reports.

Canadian Civil Liberties Association general counsel Nathalie Des Rosiers says if officers are in control of when to turn cameras on and off, police accountability is called into question. (Supplied)

Des Rosiers said she doesn't think police have thought through all the implications of having officers wear body cameras.

Besides the issue of police deciding when to turn on and off cameras, the CCLA is also concerned about where the footage goes afterward — and who decides what to keep and what to throw away.

Des Rosiers wondered whether the thought of being videotaped would deter people from calling police.

Police forces in British Columbia and Alberta have already started using the cameras. Some police forces in the United States use them too.

Thunder Bay police aim to have the cameras in place by the end of the year.