Despite the various names and affiliations for the groups that were there, there were really only two present. Those that obeyed the law and those that broke it.
I have seen various reports stating that the Nazi demonstration "triggered" the violence, and that the riots erupted "because of anger towards the city" for allowing the demonstration. Just for once I'd like to see someone take responsibility for their own actions and not point the finger at some external cause as the source of their behavior.
We all have the freedom to choose our individual responses to a given situation. If you choose to break the law, then YOU have made that choice, no one has made it for you. Whether you agree with another groups opinion or not is irrelevant. The people that have respect for the laws of this country will ensure they remain with those bounds in their actions. Those that do not will be rightfully labeled as criminals and will continue to lose the respect of the rest of us, and their cause will lose merit as well.