"In 1937, Congress passed the first federal law to discourage cannabis production for marijuana while still permitting industrial uses of the crop (the Marihuana Tax Act; 50 Stat. 551). Under this statute, the government actively encouraged farmers to grow hemp for fiber and oil during World War II. After the war, competition from synthetic fibers, the Marihuana Tax Act, and increasing public anti-drug sentiment resulted in fewer and fewer acres of hemp being planted and none at all after 1958. The Controlled Substances Act of 1970 (CSA, 21 U.S.C. §801 et. seq.) placed the control of select plants, drugs, and chemical substances under federal jurisdiction and was enacted, in part, to replace previous federal drug laws with a single comprehensive statute.43
"The CSA adopted the same definition of Cannabis sativa that appeared in the 1937 Marihuana Tax Act. The definition of “marihuana” (21 U.S.C. §802(16)) reads:
"The term marihuana means all parts of the plant Cannabis sativa L., whether growing or not; the seeds thereof; the resin extracted from any part of such plant; and every compound, manufacture, salt, derivative, mixture, or preparation of such plant, its seeds or resin. Such term does not include the mature stalks of such plant, fiber produced from such stalks, oil or cake made from the seeds of such plant, any other compound ... or preparation of such mature stalks (except the resin extracted therefrom), fiber, oil, or cake, or the sterilized seed of such plant which is incapable of germination."
"The statute thus retains control over all varieties of the cannabis plant by virtue of including them under the term marihuana and does not distinguish between low- and high-THC varieties. The language exempts from control the parts of mature plants—stalks, fiber, oil, cake, etc.—intended for industrial uses. Some have argued that the CSA definition exempts industrial hemp under its term exclusions for stalks, fiber, oil, cake, and seeds.44 DEA refutes this interpretation.45
"Strictly speaking, CSA does not make growing cannabis illegal; rather, it places strict controls on its production, making it illegal to grow the crop without a DEA permit. Regarding industrial hemp, however, growers that comply with the 2014 farm bill provision (discussed in the next section) do not need DEA approval."
Johnson, Renée. Hemp As An Agricultural Commodity. Congressional Research Service. Washington, DC: Library of Congress, June 28, 2018.