Policy Points: 

• The liberalization of medical and recreational cannabis policies may increase cannabis initiation across age groups, with increased prevalence of cannabis use among young adults and adults and weaker effects among youth. Evidence also suggests increases in cannabis-related health care utilization among adults.
• Alcohol use may decrease following medical legalization (suggesting use of cannabis in place of alcohol), but it may increase among young adults following recreational legalization (suggesting co-consumption).
• Evidence suggests a potential decrease in tobacco use across age groups and cannabis policy changes, and most studies found no change or a decrease in opioid-related outcomes, although evidence was less consistent for opioid-related mortality specifically