like the occupy movement, the protest marches against police mistreatment of blacks are a questionable use of resources; they have little effect on the opposition while eating up govt money in police overtime.
protest generally has little effect, other than giving protesters a false feeling of relevance. political action, aimed at voters, is what brings change. creating traffic snarls is no way to move hearts and minds.
i'm a veteran of the movements of the '60s, and have never believed marches were effective, even in stopping vietnamese war. stop gathering, and stasrt working, doing the less exciting but more useful job of moving voters!