In recent years, there has been a shift surrounding societal and legal perspectives on cannabis. In 2017, past-year rates of cannabis use in Canada were approximately 43% in individuals 16–24 years [125], and 18% in individuals over 25 years [19]. Moreover, there has been increasing legalization of cannabis throughout the United States, as well as nationwide legalizaiton in Canada as of October 17, 2018. The trend in legalization coincides with heightened acceptance, reduced perception of risk, and an increase in cannabis use in both adults and adolescents [23, 114, 132]. Based on the experience from commercial tobacco and the few examples of legalized recreational cannabis use (e.g. American states, such as Colorado and Washington, and in Uruguay), there is strong evidence that cannabis prevalence may increase [67, 123], which would have a disproportionate burden on those with mental illness [59]. Moreover, there will be clear societal benefits of cannabis legalization, such as shifting law enforcement away from minor crimes such as possession, which will benefit people with mental illness. Thus, from both a policy and clinical perspective, it is vital to examine the epidemiological and scientific trends of cannabis use alongside a projected growing user population.
