Which federal law introduced a ‘proof-of-efficacy’ requirement?

The Kefauver Harris Amendment is also known as the ‘Drug Efficacy Amendment.’ It is a 1962 amendment to the Federal Food, Drug, and Cosmetic Act. It introduced requirements for drug manufacturers to provide proof of the effectiveness and safety of their drugs before they could be approved. It also required drug advertising to disclose accurate information about side effects and efficacy of treatments.