A new report, Tools for Debate: US Federal Government Data on Cannabis Prohibition, focuses on the effects of the enforcement of drug prohibition in recent decades in the United States.1 It shows that efforts to suppress the selling and use of cannabis increased substantially. Adjusting for inflation, the US federal antidrug budget increased from about $1.5bn (£0.95bn; €1.1bn) in 1981 to more than $18bn in 2002. Between 1990 and 2006, annual cannabis related arrests increased from fewer than 350 000 to more than 800 000 and annual seizures of cannabis from less than 500 000 lb (226 798 kg) to more than 2 500 000 lb. In the same period the availability of illicit cannabis and the number of users rose: the retail price of cannabis decreased by more than half, the potency increased, and the proportion of users who were young adults went up from about 25% to more than 30%. Intensified enforcement of cannabis prohibition thus did not have the intended effects.

The report then turns to “unintended consequences” of prohibition, arguing that both …