Obviously there's the question of how foolproof you want the system to be, but at a minimum there should be some system that monitors and confirms it's receivin

Obviously there's the question of how foolproof you want the system to be, but at a minimum there should be some system that monitors and confirms it's receiving at least a heartbeat signal from the camera and that the camera is reporting normal functioning. If the camera drops out police dispatch should be notified who in turn should notify the officer that he needs to return to the station to have his camera replaced. One possibly more passive solution that others have mentioned is to simply discount any testimony an officer provides that doesn't have an operating camera to corroborate his statements and instead defer to non-law enforcement testimony in those cases instead of the current situation where an officer is always considered more trustworthy than anyone else. That provides very strong incentive for police to insure their cameras are working because in the event they aren't any testimony they provide would be more or less nullified and likely lose them cases.