Rating the comparative efficacy of state-level cannabis policies on recreational cannabis markets in the United States.
Cannabis policy is developing faster than empirical evidence about policy effects. With a panel of experts in substance use policy development and research, we identified key cannabis policies and their provisions enacted by U.S. states rated their theoretical efficacy in a restrictive form for reducing problematic use and impaired driving in the context of a recreational cannabis market as judged by experts and rated the strength of evidence for each policy. Using a modified Delphi approach, 9 panelists rated the comparative efficacy of 18 state cannabis policies for reducing youth use of cannabis, excessive cannabis use among the general population, and cannabis-impaired driving. Each outcome was rated separately using a Likert scale, and panelists also rated the strength of evidence supporting each efficacy rating. Investigators provided descriptions of each policy so that the nine panelists had similar conceptions of each policy. State monopoly (state owns all production, manufacturing, wholesale, and retail operations) was rated as the most effective policy for all three outcome areas. Restrictions on retail physical availability, taxes, retail price restrictions, and retail operations restrictions were also highly rated for all three outcomes. Policies regulating cannabis businesses and products were judged more effective than policies targeting consumer use and behavior. Panelists reported there was little or no direct evidence from the cannabis policy literature for most of the included policies. These ratings can facilitate research as well as policy-making decisions. A relatively small number of policies were judged to be highly effective across all three domains, indicating that for the most part adult excessive use, youth use, and impaired driving can all be reduced with the same set of policies these policies tended to target the behaviors of businesses rather than consumers. The low levels of direct evidence available to inform policy ratings, as reported by the policy panelists, makes clear the need for ongoing and sustained cannabis policy research.