The Kefauver-Harris Amendments of 1962

On Oct. 10, 1962, President Kennedy signed the Drug Amendments of 1962, Public Law 87-781¹, into law. Its title promised to “assure the safety, effectiveness, and reliability of drugs.” The middle word was the new one. For the first time, a company would have to show FDA that its drug worked before selling it.

The law is known by the names of its sponsors, Senator Estes Kefauver and Representative Oren Harris. It passed in the wake of thalidomide, a sedative that, in FDA's words, “produced thousands of grossly deformed newborns outside of the United States” and was never approved here, according to the agency's history of the 1938 act and its amendments⁴.

Those amendments also set off a review of every drug approved on safety alone since 1938, and that review is where the modern abbreviated application for copies of older drugs began.

Thalidomide and the FDA reviewer who held it up

Frances Oldham Kelsey, a physician and pharmacologist, joined FDA in 1960 as one of a handful of medical officers who reviewed new drug applications. One of the first applications assigned to her was for thalidomide, which was already sold in dozens of countries. According to an FDA history of her career³, she refused to approve it, despite constant pressure from the company, because the evidence of safety was inadequate.

About a year later, researchers in Germany and Australia linked the drug to clusters of severe birth defects that eventually involved thousands of babies. The drug was never marketed in the US. President Kennedy gave Kelsey the President's Award for Distinguished Federal Civilian Service in 1962.

Reform had been in Congress before the scandal broke. FDA's centennial history⁵ notes that Kefauver had held hearings in the years before 1962 on drug costs, weak science behind effectiveness claims, and exaggerated labeling and advertising. News of Kelsey's role, FDA's milestones timeline⁸ says, “arouse[d] public support for stronger drug regulation.”

What the 1962 amendments changed

At the core was a new evidentiary standard. The law defined “substantial evidence” as “evidence consisting of adequate and well-controlled investigations, including clinical investigations, by experts qualified by scientific training and experience,” from which experts could fairly conclude the drug would have the effect claimed on its label.

It also ended automatic approval. Under the 1938 act² (see our history of the 1938 Food, Drug, and Cosmetic Act), a new drug application became effective on the 60th day after filing unless FDA postponed it. The 1962 text¹ required FDA, within 180 days, either to approve the application or to give the applicant notice of an opportunity for a hearing.

Those rows draw on the statute and on FDA's history⁴, which lists informed consent, good manufacturing practices, the transfer of prescription drug advertising from the FTC, and greater access to company production records among the law's effects. FDA's centennial history⁵ adds that the amendments formalized good manufacturing practices, the rules explained in GxRadar's CGMP guide, and required adverse event reporting.

The naming rule is easy to overlook. The law required a prescription drug's “established name” to appear on the label “in type at least half as large as that used thereon for any proprietary name,” and the same rule applied to advertisements. Generic names had to be visible on brand products, which is part of why pharmacists and patients can match a brand to its copies. GxRadar's guide to reading a prescription label shows where those names appear now.

DESI, the efficacy review of older drugs

Pre-1962 drugs were not pulled off the market. The law gave drugs already on the market under an effective application a two-year window before the new effectiveness grounds for withdrawal applied to them. FDA then had to work through the backlog.

That process is called the Drug Efficacy Study Implementation, or DESI. FDA contracted with the National Academy of Sciences/National Research Council⁶ to make an initial evaluation of more than 3,400 drugs approved only for safety between 1938 and 1962. The review also covered the larger number of products sold without their own approval as “identical, related or similar” to those drugs. Drugs found to lack substantial evidence of effectiveness, along with their look-alikes, could no longer be marketed.

Courts backed the approach. In 1970 a federal appeals court upheld enforcement of the effectiveness amendments, ruling, as FDA's timeline⁸ puts it, that “commercial success alone does not constitute substantial evidence of drug safety and efficacy.” The same year, FDA required its first patient package insert.

How DESI produced the first abbreviated applications

DESI left FDA with thousands of copies of older drugs that needed approval, and full applications made little sense for products already found effective. According to a 2021 FDA Federal Register notice⁷, the agency “introduced the concept of an ‘abbreviated new drug application’ in 1968” as a vehicle for certain drugs affected by the review, and published a final rule creating the pathway in April 1970.

For those applications, FDA relied on the effectiveness evidence already accepted in the DESI process and judged safety from the pre-1962 applications plus later marketing experience. The Orange Book still lists products approved this way, typically identified as ANDAs, the notice says. They covered only drugs first approved before 1962.

Until 1984, the ANDA route did not reach drugs approved after 1962. That year's Drug Price Competition and Patent Term Restoration Act let FDA approve generics of brand drugs “without repeating the research done to prove them safe and effective,” as FDA's timeline⁸ describes it, with generics showing bioequivalence instead. GxRadar's count of original ANDA approvals in FDA's Drugs@FDA data⁹ shows how fast the new route filled up.

GxRadar's approvals page carries the series forward and counts 19,593 original ANDA approvals through Oct. 27, 2026. The 1984 law is covered in our Hatch-Waxman explainer, and today's process in how a generic drug gets approved.

The review that is still not finished

Sixty-four years on, DESI has not fully closed. FDA's DESI page⁶ says “a few DESI proceedings remain open without a final decision or resolution,” and that drugs in an open proceeding may stay on the market in the meantime. The page lists open proceedings that include amphetamines and an extended-release oral nitroglycerin product. Its most recent final decision was published in the Federal Register on May 27, 2026, at 91 FR 31462, roughly 60 years after the review began.