A number of studies have found a very high incidence of cases involving alcohol for the crimes of homicide, rape, and other assaultive crimes. While the research on the relationship between violent crime and drugs other than alcohol is less extensive, a consideration of the pharmacologic action of such drugs as opiates, amphetamines, barbiturates, cocaine, and phencyclidine suggests that they could contribute to violence and aggression. Cannabis does not appear to enhance assaultive behavior. In general, theories about how alcohol and drugs affect assaultive behavior have posited roles for a disinhibitory pharmacological action, individual predispositions to violence, and situational factors (especially the presence of others). These factors have implications for both prevention and treatment. A public health approach would involve the establishment of control mechanisms influencing the availability of alcohol and drugs. In the treatment of abusing violent offenders, an effective clinical approach must aim both at decreasing the probability of future intoxication and at treatment of predisposing characteristics (e.g., psychopathology). In Canada, the courts have used a specific versus general intent dichotomy in dealing with the intoxication defense, one that is at odds with the voluntary nature of drug use and the continuum of drug effects. 89 references and notes.