At the US federal level, the legal actions taken reflected constitutional restrictions under the enumerated powers doctrine prior to reinterpretation of the commerce clause, which did not allow the federal government to enact arbitrary prohibitions, but did permit arbitrary taxation. Beginning in 1883, opium importation was taxed at to per pound, until the Opium Exclusion Act of 1909 prohibited the importation of opium altogether. In a similar manner, the Harrison Narcotics Tax Act of 1914, passed in fulfillment of the International Opium Convention of 1912, nominally placed a tax on the distribution of opiates, but served as a "de facto" prohibition of the drugs. Today, opium is regulated by the Drug Enforcement Administration under the Controlled Substances Act.