What was the first law requiring drugs to be proven safe before being marketed?

The first law that mandated the proof of safety for drugs before they could be marketed was the Food, Drug, and Cosmetic Act. Enacted in 1938, this significant piece of legislation aimed to address the growing concerns over drug safety that emerged after several tragic incidents, including the infamous sulfanilamide tragedy, where a toxic formulation led to numerous deaths.

This law required drug manufacturers to provide evidence of safety and efficacy to the Food and Drug Administration (FDA) prior to the marketing of their products. It marked a significant shift from previous regulations, which did not require such thorough safety assessments, thus ensuring a higher standard of consumer protection.

Other laws mentioned, such as the Controlled Substances Act, predominantly focus on regulating drugs that have a potential for abuse, establishing classifications for controlled substances, but do not primarily address the need for proof of safety. The Drug Enforcement Administration Act relates to the enforcement and regulation of controlled substances rather than drug safety standards. Lastly, the Prescription Drug User Fee Act, which came later in 1992, introduced fees for drug applications to expedite the review process but also does not fundamentally focus on the initial requirement of proving drug safety prior to marketing.