I had a co-worker who was arrested on a domestic violence charge one time. He and his then-wife were both pretty volatile people, and they fought a lot over the phone while he was at work. One night he decided to go to a local bar with the rest of us for a few drinks after work, and she found out he wasn't working overtime like he said. She showed up at the bar, and the two of them proceeded to go at it.
When the police arrived to break it up, she was bleeding from her neck and she had a black eye. He didn't look as bad, so the police decided he was the one to charge with domestic violence. It was a real legal mess for him, since our state has some really strict domestic violence laws. He had to serve some time in jail and pay a substantial fine. They got a divorce 6 months later.