A recent memorandum by representatives of the U.S. Drug Enforcement Administration (DEA) to several U.S. senators indicates that the agency is prepared to respond imminently to a pair of administration petitions challenging marijuana's status as a Schedule I federally prohibited substance. Under the U.S. Controlled Substances Act of 1970, the cannabis plant and its biologically active components are classified as Schedule I prohibited substances — the most restrictive category available under the law.