The Kefauver-Harris amendment of 1962 required that a drug be

both safe and effective.

Explanation:

In 1962, there was a drug in Europe and Canada that was meant to treat morning sickness in pregnant women. The drug instead caused birth defects in many people.

The Federal government of the US decided that it would be best to take action against that drug and others like it from harming the U.S. like it did those other countries.

This action came in the form of the Kefauver-Harris amendment to the Federal Food, Drug and Cosmetic (FD&C) Act. According to this amendment, companies manufacturing drugs had to make sure that a drug was not only safe for consumption, but effective in treating what it is meant to treat as well.