Well put, girlintraining. Use a camera, and put the officer's face and actions in front of people who can personally shame him (or her) into remorse.
My small vow: The next time I see someone stopped by numerous police cars, I am going to stop and take a few pictures. The police try to keep us from seeing their actions, on the street, but we can look. Be the mindful observer.
WEIRD FACT ABOUT PICTURES: I have often seen, in a picture or video, brutality that was happening right under my nose...because it's often quick and quiet. TAKE A PICTURE. It will show more than the eye can see.