THE EFFECTS OF MEDICAL AND RECREATIONAL MARIJUANA LAWS ON HEALTH, SAFETY, AND ECONOMIC OUTCOMES: EVIDENCE MAPPING AND TARGETED SYSTEMATIC REVIEW - PROJECT SUMMARY
Since 1996, 33 states plus the District of Columbia have enacted medical marijuana laws allowing approved
patients legal access to therapeutic cannabis. Additionally, since 2012, ten states and the District of Columbia
have passed recreational marijuana laws legalizing adult use and—in eight states—retail sales. Although states
continue to pass and amend these laws at a fast pace, little systematic evidence is available on the health,
safety, and economic impacts of these laws. The handful of available reviews in this policy space focus mainly
on the effects of medical marijuana laws on a narrow set of marijuana use outcomes. Policymakers therefore
continue to enact, (re)design, and implement these laws with limited evidence-based guidance on their broader
societal impacts. The primary aims of this work are twofold. First, we will develop a comprehensive evidence
map of existing research examining the effects of medical and recreational marijuana laws on a diverse range
of health, safety, and economic outcomes. This effort is designed to be broad in scope to fully document extant
empirical research in this policy space. Second, we will quantitatively synthesize evidence from quasi-
experimental studies examining the effects of medical marijuana laws on targeted public health and safety
outcomes. This narrower delimitation is warranted because primary research on recreational marijuana laws and
other outcomes remains nascent. Our analytic approach will employ random effects meta-regression models
with robust variance estimation to account for dependent effect sizes coded from the same studies. This
approach will further allow us to investigate important sources of heterogeneity in effect sizes across key study
factors, including different target populations, time periods, and study designs. Lastly, we will communicate our
findings using evidence-based strategies to increase knowledge utilization among the research and policy
communities. Our work will contribute to improved policymaking on marijuana by producing systematic evidence-
based knowledge, identifying ongoing policy uncertainties, and highlighting gaps and directions for future
research.
