Congress passes the Controlled Substances Act (CSA) as part of the Comprehensive Drug Abuse Prevention and Control Act of 1970. This law establishes a “singles system of control for both narcotic and psychotropic drugs for the first time in US history.” The CSA creates five schedules to classify substances. Marijuana is placed in Schedule I, which are drugs “classified as having a high potential for abuse, no currently accepted medical use in treatment in the United States, and a lack of accepted safety for use of the drug or other substance under medical supervision.”
“The Congress asked the Department of Health, Education and Welfare for their recommendation where marijuana should be placed in the Controlled Substances Act.
The response, by letter of 8/14/70, of the Assistant Secretary for Health and Scientific Affairs [Roger O. Egeberg] is as follows:
“Some question has been raised whether the use of the plant itself produces “severe psychological or physical dependence” as required by a schedule I or even schedule II criterion. Since there is still a considerable void in our knowledge of the plant and effects of the active drug contained in it, our recommendation is that marihuana be retained within schedule I at least until the completion of certain studies now underway to resolve the issue. If those studies* make it appropriate for the Attorney General to change the placement of marihuana to a different schedule, he may do so in accordance with the authority provided under section 201 of the bill.”