Solution for optional activation
If you're in the office, it could detect the wifi network or something similar and deactivate. No reason to film cops doing paperwork, etc. and they obviously would have surveillance cameras there anyway.
Outside those areas, you should be able to turn it off but it should make a beep every 10-15 seconds to remind you that its off, and serve as a notice to the public that its off. So if you go to the bathroom, you turn it off, and when it keeps beeping it reminds you to turn it back on again. Ditto if you are conducting a sensitive interview - it lets the person being interviewed know the camera is still off (though perhaps in such situations the cop just removes the camera, speaks into it "I'm removing it because I'm going to interview a rape victim who doesn't wish to be on camera" and when he retrieves it it'll be beeping to remind him to put it back on.
Biting the hand that feeds IT
