Marijuana use for medical purposes was available in the United States in extract form until the passage of the Marijuana Tax Act (1937). In 1969, the Supreme Court ruled the Marijuana Tax Act unconstitutional. Congress responded by passing the Controlled Substances Act (CSA) in 1970, which, among other things, declared marijuana (and other substances) as having a high potential for abuse, no accredited medical use, and lack of accepted safety under medical supervision. Today, 23 states and Washington, D.C. have legalized marijuana for medical use, despite this being a violation of federal law. Although current evaluation of marijuana for medical use is mired with controversy, this presentation will demonstrate that both advocates and opponents of the medical use of marijuana stake their positions despite the lack of clinical or objective scientific evidencein both the passage of the CSA, nor the resulting consequences that the CSA classification of marijuana has created in terms of demonstrating its safety and efficacy.