Increased funding for cannabis prohibition has increased cannabis seizures and arrests, but the assumption that this reduces cannabis potency, increases price or meaningfully reduces availability or use is inconsistent with surveillance data the US federal government has itself collected. On the contrary, the falling prices imply that supply is increasing faster than demand. Given that cannabis prohibition has clearly failed to achieve its stated objectives and has also resulted in a range of serious unintended harms, regulatory models should be given urgent consideration, both in the United States and in other settings. In light of the widespread and often free availability of cannabis that exists despite aggressive criminal justice measures, it may be incorrect to assume that the legal regulation of cannabis production supply and use—if responsibly developed, implemented and enforced by appropriate authorities—will result in increased cannabis use or an overall increase in cannabis-related harms, since there are a range of mechanisms that could contribute to reduced cannabis use in this context. However, successfully reducing rates of cannabis-related harm will likely require the implementation of strict regulatory mechanisms which are associated with reducing the harms of other legal substances and are too commonly underutilized in the areas of tobacco and alcohol control.