Russians started putting dash-cams on their cars to have their own evidence to take to court against their corrupt police force, and it worked (from what I have read. If anyone lives in Russia, please comment!)
I also think cameras at the scene of the most heinous crimes being committed would be good - make the Congress and Senate and President do a "Truman Show." Every conversation, yes, even when they pee, should be broadcast live. "National Security" is MOST threatened when these devils work behind closed doors.
This is the article that got my posting privileges revoked: