Context: As of November 2018, medical cannabis was legal in 33 US states and recreational cannabis in 10, mostly enacted via ballot initiative.
Methods: We identified 32 cannabis legalization initiatives from 2004 to 2016 and obtained campaign contribution and state political and demographic data. After exploratory analyses of 15 potential independent variables, we quantified effects of 4 factors (initiative year, voter turnout, population born before 1946, advocate funding advantage) on voter support and likelihood of passage.
Findings: A small number of campaign contributors dominated both sides of the issue, with little involvement by health advocates. Time and turnout, not money, were the factors most associated with electoral outcomes, consistent with increases in public opinion favoring cannabis legalization over time. Year, turnout, and population age were associated with voter support, while year, turnout, and advocate funding advantage were associated with likelihood of passage. When adjusting for an anomalous result, initiative year was the only variable that remained significantly associated with odds of passage, with a 1-year increase in initiative date associated with 2.02 times higher odds of passage (p < .01).
Conclusion: These results underscore the importance of health advocate participation in developing cannabis legalization frameworks.