The U.S. Senate

The U.S. House of Representatives

Federal Legislative Information via THOMAS (Library of Congress) 

The U.S. Food and Drug Administration (FDA)
FDA has broad responsibilities for ensuring the safety of food, drugs, cosmetics, and medical devices. The Federal Food, Drug, and Cosmetic Act is one of the key authorizing statutes specifying FDA’s responsibilities and authorities. The Dietary Supplement Health and Education Act of 1994 or DSHEA establishes manufacturing standards and permissible claims for nutritional supplements.

U.S. Code of Federal Regulations 

The Federal Trade Commission (FTC)
The FTC is charged with protecting consumers from unfair business practices. This jurisdiction includes oversight of consumer advertising to ensure that it is not false or misleading.

The National Advertising Division (NAD) of the Council of Better Business Bureaus (CBBB)
The NAD, a self-regulatory body of the business community, maintains a vigorous advertising oversight program that frequently adjudicates challenges to over-the-counter drug advertising.

The U.S. Drug Enforcement Administration (DEA)
DEA has responsibility for combating drug trafficking, including efforts to prevent the diversion of legal drugs and precursor chemicals to manufacture illegal drugs. The Controlled Substances Act (CSA) is one of DEA’s key authorizing statutes. Additionally, DEA's Office of Diversion Control oversees the scheduling of precursor chemicals to manufacture methamphetamine as outlined in the Combat Methamphetamine Act Epidemic of 2005 (CMEA) .