I have heard a lot about gun violence while drunk, PCP, or other drugs (cocaine and barbiturates come to mind). Maybe even caffeine OD? Never heard of a case of someone high on Marijuana go shoot someone. I ask this as I hear some say legalization of MJ will cause increase in violent crime, but that is dubious considering the typically sedative effects of MJ. A leading theory is the user himself has naturally strong violent tendencies, after all it is illegal. Of course, because it is illegal it makes it very difficult to do a proper scientific study, despite a potential for positive medical benefits.