A friend who was a police officer for 25 years told me things changed a little bit for the better in his department after they became the target of a federal investigation into the use of excessive force.
Apparently, one evening, several police officers brutally beat a young black "suspect" who was already in handcuffs and lying on the ground. What none of the officers knew at the time of the beating was that their "suspect" was actually an undercover police officer, working for the same department in vice. Oops!
My friend was there and said he watched other officers punching and kicking the "suspect" while he was lying handcuffed on the ground. He said it was difficult, but that he ended up having to actually testify against some of his fellow officers in federal court. Apparently, a couple of the officers ended up getting fired, and I think one actually went to jail for awhile as a result of the investigation.
My friend said that what happened that night wasn't at all unusual. According to him, it was pretty common for officers to take out some of their aggression by "roughing suspects up a little bit." The only thing that was out of the ordinary, that time, was that their suspect ended up being another cop.
I like my friend and think he's generally a good guy, but he admitted to me that if it hadn't been for the federal investigation of the incident, nobody, including himself, would've ever reported their fellow officers' beating of an unarmed suspect lying handcuffed on the ground.
Sorry, but there are no facts of any case which justify police officers punching and kicking unarmed suspects who are already lying on the ground handcuffed. Officers who do those things should be arrested, prosecuted and sent to prison where they belong.