Marijuana 1-to-3 Act of 2021 This bill moves marijuana to a lower schedule of the Controlled Substances Act. Specifically, it directs the Drug Enforcement Administration to transfer marijuana from schedule I to schedule III. (A schedule I controlled substance is a drug, substance, or chemical that has a high potential for abuse; that has no currently accepted medical use; and that is subject to regulatory controls and administrative, civil, and criminal penalties under the Controlled Substances Act. A schedule III controlled substance is a drug, substance, or chemical that has less potential for abuse than a schedule I or II substance; that has a currently accepted medical use; and that has low or moderate risk of dependence if abused.)