I read a good sci-fi book recently about the possibilities for a device like this. (It was the one about orcs raiding an MMORPG bank in Scotland and causing a financial panic. I don't remember the title but if you Google it you should probably find it fairly quickly.)

They didn't tag the people -- they tagged the cops. I'd be 150% in favor of that -- the camera preserves all the evidence impartially, regardless of whether it shows the cop in the right or in the wrong, and the minority of bad apples would probably clean up their act a bit if they knew they were being watched by something they could not intimidate or cajole into silence. Plus as a public servant, while they are on the clock, cops have zero expectation of privacy.

If I had my druthers I'd give them to everyone with a badge and make their use compulsory 100% of the time when in uniform, with a 5 minute time-out button for bathroom breaks which, if you punch in the middle of a traffic stop, means you lose your badge.

See the book for how it would revolutionize policing. The cops could use simple voice commands to produce authenticated timestamps for, e.g, arrests and collecting evidence. It would greatly simplify arrest reports and the like. It would make a HUGE portion of criminal cases even more open and shut than they already are -- "Look, we've got you on video swinging your fist at a cop. Please guilty to the possession charge and resisting arrest, or you'll be convicted of assault."