Does cannabis use play a causal role in subsequent violence? The available research suggests an association between cannabis use and risk of being a perpetrator of violence. Indeed, cannabis users are at increased risk of carrying out severe violence, including aggravated assault, sexual aggression, fighting, and robbery. There is also evidence on the association between cannabis use and subsequent victimization (e.g., intimate partner violence). Individuals with severe mental disorders also show an incremented risk of violence, considering their higher rate of cannabis use compared to the general population. Possible mechanisms underlying this association involve (1) the neurobiological effect of the substance after acute use, but also during abstinence and withdrawal, and (2) social factors, such as the violent/criminal lifestyles of cannabis users. However, it is important to acknowledge the limitations of the current literature. Most available studies are cross-sectional and retrospective, so it remains difficult to disentangle the direction of the association. Despite that, cannabis use may be a useful preventive intervention target, particularly among at-risk groups such as psychiatric patients.

Police are the gatekeepers to the criminal justice system. Without police officers investigating offenses and bringing cases to prosecutors, criminal courts would have little to do. Thus, the decisions made by police are critical to understanding Mass Incarceration.