No need for violence. We could advance the cause of lot of things, such as legalized marijuana, by targetting and boycotting consumer products. If you hit certain corporations hard enough, such as the music industry, and demand action, they would be forced to lobby for your interests with far better resources than any individual, or even most groups, could muster. Petitions end up in the trash can. When money talks, nobody walks.

The problem is that most people are unwilling to deny themselves any of the convieniences they are accustomed to.