A Practice Note providing an overview of the Drug Enforcement Administration (DEA) and its authority to carry out the mandates of the Comprehensive Drug Abuse Prevention and Control Act of 1970, commonly referred to as the federal Controlled Substances Act (CSA). This Note focuses primarily on the CSA requirements related to the legitimate industry, that is, the closed chain of distribution for controlled substances established by the CSA and regulations promulgated by DEA. It also discusses DEA's enforcement authority and corresponding state requirements related to controlled substances.