Useful summary of precedent on limits of dissent. Doesn't seem as though much of the recent police violence can be justified under these criteria, but it is very difficult to get reprimands, let alone convictions. Another item to add to the list of demands wrt government of the people, by the people and for the people, rather than the 1%.
Just How Much Can the State Restrict a Peaceful Protest?
by Braden Goyette, ProPublica at Truthout