I used to play football as a high schooler. Some of my football buddies became cops and I was invited to their parties. As most people know, police officers tend to form little sub cultures within their communities. This groups had a real "us vs. them" mentality - to the point where I was no longer invited. They definitely had the attitude that people in general were either stupid or criminals. In any case, the stories these guys told each other were very upsetting. They talked (and laughed) about how they would beat or frighten the people they had arrested. If there were complaints, the cops would automatically back each other up. And not just people who had broken the law. They routinely harrassed visible minorities. In one instance that I can recall, they maced a kid (a minority) riding his bike as they drove by in the cruiser. Great laughter as they described the subsequent wipeout... and the kid hadn't done a thing wrong!
I was the only one there who seemed to have a problem with this. And you know, these were not bad guys in high school. They were good buddies, decent people, and friends. I guess there is just something about having that authority or seeing the things they see that does this do them.