Here's a video of a Seattle Police Officer using racial slurs and kicks him in the head. Alot of times police officers use force that the general public doesn't understand, but in this case the male is detained and appears to be cooperating with police, so it appears this officer crossed the line.
As police officers we live in a world now where almost everyone carries a phone that records video, so if officers cross that line you'll be seeing more and more of these videos...