Get real, people
@ Graham Dawson & AC - your claim that Antifa "are no better than the Nazis" is utter bollocks. How, exactly, is giving a few boneheads a good hiding equal to the systematic murder of ten million people ? You may as well say that a five-year-old boy who hits his little sister is just as bad as the Yorkshire Ripper.
@ Roger Pearse - saying "no-one believes in Naziism any more...there is not the slightest risk to the rest of us" really does fly in the face of reality. Perhaps you should take a holiday in Moscow or St Petersburg, and be sure to advertise the fact that you're a foreigner (or just do a bit of googling to find out how many murders by gangs of swastika'd skinheads are going on over there).
There are two solid bases for non-legally-sanctioned direct action against fascists. The legal basis is that the argument of "force majeure" applies, as it did with the peace campaigners who gave some missiles a good seeing-to with a hammer - whilst they were doing something technically illegal, the fact that they did it to stop a much greater evil means that they can be excused.
The moral basis is the Voltairism of "I don't agree with you, but will fight to the death to defend your right to say it". This is often employed by namby-pamby liberals & pacifists to justify why they will happily let fascists say whatever they want (as when Nick Griffin was allowed to speak at the Oxford Union)... but those people are blissfully ignoring the logical conclusion of the statement : there actually are some people - the fascists both in government and in gangs - that we have to fight to the death, to defend everyone else's rights.
Skull & Bones - for the F.C. St. Pauli fans everywhere.