I think you heard the story wrong. Yeah, turns out it was a guy, not a woman. He admitted to giving the cop a dirty look, that's all. There is video showing what happened before that other video starts, and I don't see him carrying a drink. It's all here: http://gothamist.com/2011/10/14/hiv_positive_protester_says_cop_who.phpHe threw a liquid in his face before that. He deserved it. There was an interview with him on Youtube a few days ago.
Don't take everything at face value there Morphy.
It doesn't matter what he did, it's not part of any arrest procedure to haul off and punch someone who's walking away from you. Anyway, the cop's wild punch apparently didn't land flush, instead hitting the dudes ear and ripping out his earring. The victim was HIV positive and his message to the cop was 'you better get tested.' Now wouldn't that be some karma in work.