21 CFR 291.505
Partly because of the diversion and abuse of methadone, even after the FDA's regulations for methadone treatment became effective in 1973, a series of bills were passed by the United States Congress in 1974 authorizing the FDA, the DEA, and the DHHS to regulate maintenance treatment of Opiate Dependence with methadone . The resulting regulations amended the CSA to allow for prescription of methadone for detoxification or maintenance in federally licensed programs, but not in physician's offices.
88 Stat. 124, 21 U.S.C. 802, 823, 824 (1970 ed., Supp. IV)