: McSpotlight: It's also worth noting (speaking as an eye-witness) that violence started when the police (who had maintained a heavy presence throughout the day) ran a protestor down with a riot van (see a picture here); breaking her thigh and causing abdominal injuries; then prevented an ambulance getting to the injured woman for 25 minutes on the grounds that the protestors constituted a danger to the safety of the ambulance crew. After that sort of act, it's hardly surprising things turned ugly, is it?
Having been to countless demonstrations, it is almost common knowledge among protestors that violence is virtually always preceeded by an agressive charge by the police. Very peaceful demos have been quickly turned to mayhem by a sudden appearance of a tack squad bearing clubs and mace.
I remember one demo with Earth First! There were a number of "affinity groups" prepared to get arrested. There were hundreds of cops from four counties, each with their different uniforms from irredescent blues to shiny black. Our group and others "trespassed", sat down, and waited for arrests. The police lines <1>backed up!. Our little groups moved forward and sat down again. Again, the police lines moved back. The upshot was that We Couldn't get arrested! The whole afternoon was absolutely peaceful. We finally left - there were even some smirks of admiration - from both sides!.
Earth First! is not your parlor chair "activist". What it proved to me is that if the police don't want a violent confrontation, they won't get one.