From the Document: "The Controlled Substances Act [hyperlink] (CSA) places various substances in one of five schedules based on their medical use, potential for abuse, and safety or risk for dependence. The five schedules [hyperlink] are progressively ordered with Schedule V substances regarded as the least dangerous and addictive and Schedule I substances considered the most dangerous and addictive. Schedule I substances are considered to have a 'high potential for abuse' with 'no currently accepted medical use in treatment in the United States.' The CSA prohibits the manufacture, distribution, dispensation, and possession of Schedule I substances except for federal government-approved research studies. Marijuana is listed as a Schedule I controlled substance [hyperlink] under the CSA[.] [...] The Schedule I status of marijuana means that the substance is strictly regulated by federal authorities. Yet, over the last several decades, most states and territories have deviated from across-the-board prohibition of marijuana, and now have laws and policies allowing for some cultivation, sale, distribution, and possession of marijuana."
CRS Insight, IN11204
Congressional Research Service: https://crsreports.congress.gov/