"With increasing use of marijuana and other street drugs during the 1960s, notably by college and high school students, federal drug-control laws came under scrutiny. In July 1969, President Nixon asked Congress to enact legislation to combat rising levels of drug use. Hearings were held, different proposals were considered, and House and Senate conferees filed a conference report in October 1970. The report was quickly adopted by voice vote in both chambers and was signed into law as the Comprehensive Drug Abuse Prevention and Control Act of 1970."
Eddy, Mark, "Medical Marijuana: Review and Analysis of Federal and State Policies," Congressional Research Service (Washington, DC: March 31, 2009), p. 3.