Six policy lessons relevant to cannabis legalization.

Cannabis (marijuana) has been legalized for recreational and/or medicinal use in many US states, despite remaining a Schedule-I drug at the federal level. As legalization regimes are established in multiple countries, public health professionals should leverage decades of knowledge from other policy areas (e.g., alcohol and tobacco regulation) to inform cannabis policy. Identify policy lessons from other more established policy areas that can inform cannabis policy in the United States, Canada, and any other nations that legalize recreational cannabis. Narrative review of policy and public health literature. We identified six key lessons to guide cannabis policy. To avoid the harms of "a medical system only in name," medical cannabis programs should either be regulated like medicine or combined with the recreational market. Capping potency of cannabis products can reduce the harms of the drug, including addiction. Pricing policies that promote public health may include minimum unit pricing or taxation by weight. Protecting science and public health from corporate interest can prevent the scenarios we have seen with soda and tobacco lobbies funding studies to report favorable results about their products. Legalizing states can go beyond reducing possession arrests (which can be accomplished without legalization) by expunging prior criminal records of cannabis-related convictions. Finally, facilitating rigorous research can differentiate truth from positive and negative hype about cannabis' effects. Scientists and policymakers can learn from the successes and failures of alcohol and tobacco policy to regulate cannabis products, thereby mitigating old harms of cannabis prohibition while reducing new harms from legalization.