Occupy Cleveland canceled May Day protest plans to march in the city because of this:

[pinboy3niner]

55. You think Occupiers haven't confronted disruptors, en masse?

Swarming and demanding has been tried-and it failed. Even large numbers of Occupiers can't make someone do or not do something.

Occupiers DO stand up to disruptors--with their cameras and with nonviolent tactics to isolate them and call attention to their actions.

Black bloc is relatively new, perhaps something that wasn't, in the days of the VN and civil rights protests, the organized tactic that it is today. It's not just a problem of controlling protest participants who may get a little out of line.

These are organized disruptors who are determined to act out in ways that are intentionally and directly contrary to the intentions and goals of the Occupy movement. They don't respond to castigation or shaming. And the superior numbers of Occupiers means nothing to them when they know that Occupiers are committed to nonviolent action.

Please consider our responses--mine, and that of ellisonz. We two have actually marched in the streets together in Occupy L.A. actions. Believe me, if anybody offered a better idea for dealing with this challenge we would glom onto it gratefully.