Most LEOs I know, hated the cameras, at first. But love them now. It helps prevent people from lying about the officers conduct, more often than exposing bad behavior. I would have gladly worn one. But it has only recently become mandatory. I left law enforcement in May 2018. We were not provided body cams, at that time. Although several departments had only recently been made to wear them.
To my knowledge, it is not possible, for the officer, to turn off the camera… But it can easily be obstructed, during a close contact situation, or it can become dislodged, in a confrontation. Overall monitoring, of behavior is good. But it’s the guns that need a camera the most, in my opinion.
At this point, for instance, if multiple officers fire on a person, ballistics tests are required to determine who actually hit the person. That only provides minimum information though. It cannot indicate the variables leading up to the reason for discharging the firearm. Plus, people fire handguns, with both arms extended. One for the dominant hand, which pulls the trigger, and the other hand is placed under the grip, for accuracy, and control of muzzle rise. This will frequently block a chest mounted camera’s view, of a very important part of an officer involved shooting… A camera placed under the barrel, would show much more, and would be pretty much free of any obstruction of view.
Many falsified reports, of wrongful shootings, claim that the assailant was an imminent threat (holding a knife, or gun etc.) A camera on the gun, could prove, or disprove that, with much greater reliability, than a chest mounted one.