Indeed, I agree that people do have the moral right to express their protest through unlawful activities that do not harm other people directly.
So that would exclude smashing other people's windows or burning other people's property, right? Or does that only harm other people "indirectly"?
I don't draw the line at the same place. Sometimes you have to do things which are unlawful and which harm other people directly.
But when we have a picket line, and one member uses a screw to scratch a nice deep groove in the boss's car (or some third party car) as they cross - and where this [b]was not authorized[/b] by the union - that member will be charged and sanctioned long before the state does (even if they never do). And it's irrelevant whether the picket line is lawful, or whether the strike has been banned by back-to-work legislation, or it's in violation of some interlocutory injunction.
The key is individual heroics which risk causing harm [b]to the struggle[/b], irrespective of whether they are legal or not, or harm some "other people" or not. At least, that's where I draw the line.