No more pounding the beat, no more beating the suspects

Good news - but see this:

"The court heard Hanvey had a previous conviction in 1999 for assaulting a man, in similar circumstances, who was in detention at Bootle Street police station in Manchester."

So why was he still employed as a policeman? Beating up suspects is after all something of a big no-no for the police, or so we are led to believe. If I were to be convicted of assaulting one of our customers I would not expect to find my job waiting for me on my return from jail. Why do Greater Manchester Police have lower standards than a bank?