Earlier quoted context omitted.
There is no national body that oversees police, but Chicago has the Independent Police Review Authority. However IPRA rarely upholds complaints against police (it's staffed by ex-cops and other people connected to the police), and recently an investigator was fired after finding a shooting unjustified[1]. [1] http://www.wbez.org/news/city-fires-investigator-who-found-c...
"Since its 2007 creation, IPRA has investigated nearly 400 civilian shootings by police and found one to be unjustified." Alrighty, then...
I know every discharged weapon in the UK is followed by immediate officer suspension and investigation, and I suspect very few are actually ruled as bad and rightly so.