Capturing Heterogeneity in Medical Marijuana Policies: A Taxonomy of Regulatory Regimes Across the United States

ABSTRACT

Background: There is considerable movement in the U.S. to legalize use of cannabis for medicinal purposes. Twenty-three U.S. states and the District of Columbia have laws that decriminalize use of marijuana for medicinal purposes. Most prior studies of state medical marijuana laws and their association with overall marijuana use, adolescent use, crime rates, and alcohol traffic fatalities have used a binary coding of whether the state had a medical marijuana law or not. Mixed results from these studies raise the question of whether this method for measuring policy characteristics is adequate. Objectives: Our objective was to develop a validated taxonomy of medical marijuana laws that will allow researchers to measure variation in aspects of medical marijuana statutes as well as their overall restrictiveness. Methods/Results: We used a modified Delphi technique using detailed and validated data about each state's medical marijuana law. Three senior researchers coded elements of the state laws in initiation of use, quantity allowed, regulations around distribution, and overall restrictiveness. We used 2013 data from the U.S. National Survey on Drug Use and Health to assess validity of the taxonomy. Results indicate substantial state-level variation in medical marijuana policies. Validation analysis supported the taxonomy's validity for all four dimensions with the largest effect sizes for the quantity allowed in the state's medical marijuana policy. Conclusions/Importance: This analysis demonstrates the potential importance of nondichotomous measurement of medical marijuana laws in studies of their impact. These findings may also be useful to states that are considering medical marijuana laws, to understand the potential impact of characteristics of those laws.

KEYWORDS:

• Medical marijuana
• marijuana
• marijuana laws
• drug policy
• qualitative methods

Acknowledgment

A previous version of this article was delivered to the American Society of Health Economists, Los Angeles, California, in June 2014.

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the article.

Funding

This study was supported by a grant from the National Institute on Drug Abuse (R01 DA034091-01).

Additional information

Notes on contributors

Susan A. Chapman

Susan A. Chapman, PhD, RN, FAAN, is Professor in the Department of Social and Behavioral Sciences, UCSF School of Nursing, and Faculty at the Healthforce Center and the Philip R. Lee Institute for Health Policy Studies. She is Co-Director of the Masters and Doctoral programs in Health Policy at the School of Nursing. Susan received her B.S. from the University of Iowa, her M.S from Boston College, her M.P.H from Boston University, and her PhD in Health Services and Policy Analysis from UC Berkeley. Her scholarly work focuses on health workforce research, health policy analysis, and program evaluation.

Joanne Spetz

Joanne Spetz, PhD, FAAN, is Professor at the Philip R. Lee Institute for Health Policy Studies at the University of California, San Francisco, and Associate Director for Research at the Healthforce Center at UCSF. She is the Principal Investigator and Director of the UCSF Health Workforce Research Center on Long-Term Care. She has conducted research on nursing labor markets, education, shortages, and employment for 25 years. She also has led research on the impact of the Affordable Care Act on the health workforce, organization of the hospital industry, effects of health information technology on hospital staff and patients, effect of medical marijuana policy on youth substance use, and quality of patient care.

Jessica Lin

Jessica Lin is currently an MPH candidate at the University of Michigan in the Health Management and Health Policy department. Before coming to Michigan, she worked at UCSF's Institute for Health Policy Studies as a Research Analyst and graduated with a BA in public health from UC Berkeley. After graduating from Michigan in May 2016, she plans on heading to the Government Accountability Office as an Analyst.

Krista Chan

Krista Chan graduated with Bachelor's degrees in Public Health and Economics at the University of California, Berkeley, where she studied racial disparities in health insurance coverage. She has worked at the Institute for Health Policies and Healthforce Center at the University of California, San Francisco, for over a year, offering research assistance in qualitative and quantitative studies on the health care workforce, medical marijuana policy, and other topics.

Laura A. Schmidt

Laura A. Schmidt, PhD, is Professor of Health Policy in the School of Medicine at the University of California at San Francisco. She holds a joint appointment in the Philip R. Lee Institute for Health Policy Studies and the Department of Anthropology, History and Social Medicine. Dr. Schmidt is also Co-Director of the Community Engagement and Health Policy Program for UCSF's Clinical and Translational Sciences Institute. She received her PhD training in sociology at UC Berkeley and while there, completed doctoral coursework in public health, and also holds a master's degree in clinical social work. Dr. Schmidt's central goal is to bridge the worlds of biomedical research, clinical practice, and population health in ways that help us better understand some of the most pressing issues in health and health care today: the widening of health disparities and the societal regulation of risk factors in chronic disease. Substantive areas of her research include addiction, poverty, obesity-related metabolic disease—all burdens that are profoundly influenced by the organization of care and the social environment. A hallmark of her research is blended methodologies: she incorporates historical-archival, ethnographic, and quantitative methods into most of her studies as a way to cross-validate findings and better interpret their meaning.