Over the last forty years, perhaps no issue has affected the United States’s criminal justice system as profoundly as has drug policy. Since President Nixon declared drug abuse “America’s public enemy number one,”1 concerns about the manufacture, distribution, and possession of drugs have remained at the fore of criminal justice policy discussions.2 President Reagan’s subsequent pronouncement of drugs as “an especially vicious virus of crime” set a course for national drug policy that emphasized enforcement and punishment over treatment to “win the war on drugs.”3 Throughout the 1980s, increasing public concern about the effects of drug abuse4 further pressured policymakers at the state and federal levels to adopt new mandatory sentences and sentence enhancements that increased the probability and length of prison sentences.