Natural Experiments in a Complex and Dynamic Environment: The Need for a Measured Assessment of the Evidence
Year: 2013
Type: article
Abstract: While there are several areas of agreement with the points made by Anderson and Rees, we do have a few key points of departure.First, we disagree with their conclusion that much has been learned from "clearly defined natural experiments" of medical marijuana liberalization policies, not because this literature lacks methodological rigor but because it has not adequately accounted for state-level policy heterogeneity and implementation uncertainty.We addressed the first point above, and take up the second point here.While the passage of state medical marijuana laws may have indicated a clear shift in the norms or perceived harmfulness of marijuana among voters, the initial laws that passed in most states did not contain clearly specified legal sources of supply.Without an authorized distribution system and clarity on where potential home cultivators could obtain starter plants or seeds, patients had no obvious way outside the black market to access the medicine the law said they could use.Consequently, quasi-legal medical marijuana collectives and retail outlets sprouted up in many early adopting states.Importantly, as these developments were incremental and often subject to variable enforcement activity, legislative amendments, and court rulings, the static binary policy indicators used in most studies on the effects of medical marijuana laws likely obscure as much as they reveal.Even in Colorado, where supply channels were fairly explicit in the initial law and cooperatives emerged quickly, it took several years and numerous court cases before the legal legitimacy of dispensaries was resolved in terms of legal protection under state law (Office of the State Auditor, 2013).In addition to the uncertainty within states, there also remained tremendous uncertainty regarding how the federal government would respond.The impact of the uncertainty on individual behavior is evident in Colorado, where the state witnessed an enormous rise in the number of registered patients after a 2009 memo written by Deputy Attorney General David Ogden that provided formal guidelines to federal prosecutors not to pursue legitimate medical patients who were in compliance with state laws (Office of the State Auditor, 2013).On January 31, 2009, prior to the memo, the Colorado Department of Public Health and Environment reported that 5,051 patients had active registration cards.By January 31, 2010, just one year later and a few months after the memo, the state reported 55,469 active registered patients, a tenfold increase.The fact that it took time for these state and federal legal issues to get resolved, along with the wait-and-see approach by patients for the policy environment to become more settled, suggests that one should be cautious inferring policy implications from the initial effective policy dates.While the effective dates may in fact coincide with a shift in norms toward marijuana, marijuana use and other public health outcomes could continue to change
DOI: 10.1002/pam.21730
Authors: Rosalie Liccardo Pacula, Eric L. Sevigny
Institution: University of South Carolina
Language: English
Subfield: Pharmacology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Funder: National Institute on Drug Abuse
OpenAlex ID: W2123638575