global review:"medical and recreational legalization increase cannabis use, with weaker effects among youth. In addition, potential substitution effects were identified for other substances (e.g., alcohol, tobacco, opioids), excepting complementary alcohol use among young adults" post-legalisation
milbank.org
Impacts of Global Cannabis Policy Changes on Substance Use: A Systematic Review of Quasi-Experimental Studies | Milbank Quarterly
Substantial changes in cannabis policies are occurring globally; however, the impacts of these reforms on cannabis use, as well as downstream effects on other substance use, remain unclear.