This paper sheds light on previous inconsistencies identified in the literature regarding the relationship between medical marijuana laws (MMLs) and recreational marijuana use by closely examining the importance of policy dimensions (registration requirements, home cultivation, dispensaries) and the timing of when particular policy dimensions are enacted. Using data from our own legal analysis of state MMLs, we evaluate which features are associated with adult and youth recreational and heavy use by linking these policy variables to data from the Treatment Episodes Data System (TEDS) and the National Longitudinal Survey of Youth (NLSY97). We employ differences-in-differences techniques, controlling for state and year fixed effects, allowing us to exploit within-state policy changes. We find that while simple dichotomous indicators of MML laws are not positively associated with marijuana use or abuse, such measures hide the positive influence legal dispensaries have on adult and youth use, particularly heavy use. Sensitivity analyses that help address issues of policy endogeneity and actual implementation of dispensaries support our main conclusion that not all MML laws are the same. Dimensions of these policies, in particular legal protection of dispensaries, can lead to greater recreational marijuana use and abuse among adults and those under the legal age of 21 relative to medical marijuana laws without this supply source.

Recent work finds that medical marijuana laws reduce the daily doses filled for opioid analgesics among Medicare Part-D and Medicaid enrollees, as well as population-wide opioid overdose deaths. We replicate the result for opioid overdose deaths and explore the potential mechanism. The key feature of a medical marijuana law that facilitates a reduction in overdose death rates is a relatively liberal allowance for dispensaries. As states have become more stringent in their regulation of dispensaries, the protective value generally has fallen. These findings suggest that broader access to medical marijuana facilitates substitution of marijuana for powerful and addictive opioids.

for valuable feedback, as well as participants of the 2014 SIEPR/Sloan Working Longer Conference at Stanford University and the Harvard Labor Economics Seminar for their many helpful comments. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. At least one co-author has disclosed a financial relationship of potential relevance for this research. Further information is available online at http://www.nber.org/papers/w22452.ack NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

IMPORTANCEGiven high rates of opioid-related fatal overdoses, improving naloxone access has become a priority. States have implemented different types of naloxone access laws (NALs) and there is controversy over which of these policies, if any, can curb overdose deaths. We hypothesize that NALs granting direct authority to pharmacists to provide naloxone will have the greatest potential for reducing fatal overdoses.OBJECTIVES To identify which types of NALs, if any, are associated with reductions in fatal overdoses involving opioids and examine possible implications for nonfatal overdoses.DESIGN, SETTING, AND PARTICIPANTS State-level changes in both fatal and nonfatal overdoses from 2005 to 2016 were examined across the 50 states and the District of Columbia after adoption of NALs using a difference-in-differences approach while estimating the magnitude of the association for each year relative to time of adoption. Policy environments across full state populations were represented in the primary data set. The association for 3 types of NALs was associated: NALs providing direct authority to pharmacists to prescribe, NALs providing indirect authority to prescribe, and other NALs. The study was conducted from January 2017 to January 2019.EXPOSURES Fatal and nonfatal overdoses in states that adopted NAL laws were compared with those in states that did not adopt NAL laws. Further consideration was given to the type of NAL passed in terms of its association with these outcomes. We hypothesize that NALs granting direct authority to pharmacists to provide naloxone will have the greatest potential for reducing fatal overdoses. MAIN OUTCOMES AND MEASURESFatal overdoses involving opioids were the primary outcome. Secondary outcomes were nonfatal overdoses resulting in emergency department visits and Medicaid naloxone prescriptions. RESULTSIn this evaluation of the dispensing of naloxone across the United States, NALs granting direct authority to pharmacists were associated with significant reductions in fatal overdoses, but they may also increase nonfatal overdoses seen in emergency department visits. The effect sizes for fatal overdoses grew over time relative to adoption of the NALs. These policies were estimated to reduce opioid-rated fatal overdoses by 0.387 (95% CI, 0.119-0.656; P = .007) per 100 000 people in 3 or more years after adoption. There was little evidence of an association for indirect authority to dispense (increase by 0.

We would like to thank seminar participants at the Conference of the American Society of Health Economists and the APPAM Fall Research Conference for helpful comments, especially from our discussants Dean Lillard and Melinda Buntin. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.