1938 Food, Drug, and Cosmetic Act (FDCA)

Soon after its passage, shortcomings in the 1906 act became apparent. For example, the government had no authority to review products prior to marketing. Reform started with the Tugwell Bill in 1933; however, the legislation was deadlocked until the scandal surrounding Massengil's Elixir Sulfanilamide occurred in the autumn of 1937, illustrating to the public the shortcomings of the 1906 act. Containing an untested solvent, diethylene glycol (DEG), similar to anti-freeze, the elixir caused 107 deaths.

To prevent similar disasters, Congress crafted the modern FDCA in 1938, requiring drug manufacturers to submit an application showing that new drugs were safe before they could be marketed, and gave FDA the authority to regulate cosmetics and medical devices. Although some stakeholders like the American Medical Association questioned USP's special recognition in law, USP's status as an official compendium and role in the adulteration and misbranding provisions of the Act were confirmed. Congress also added the requirement of USP identity to those for strength, quality, and purity, recognized USP requirements for packaging and labeling, and forbade the Secretary of Agriculture from unilaterally amending or supplementing the USP-prescribed tests or methods of assay.