The decline of therapeutic research with LSD in the United States during the 1960s is often blamed on controversy over recreational use, but research difficulties were equally responsible. The Kefauver Harris Drug Amendments of 1962 required proof of efficacy through controlled clinical trials, yet LSD psychotherapy—which uses the drug to catalyze psychological treatment—clashed with controlled trial methodology on theoretical and practical levels. This made it hard to demonstrate efficacy. Examining post-1962 trials shows that the new emphasis on trial design diverted attention from the therapeutic method itself, offering a new perspective on LSD psychotherapy's demise and the implications of the 1962 drug amendments.
The decline of LSD-assisted psychotherapy research in the USA during the 1960s is often attributed to prohibitive federal regulations aimed at curbing recreational use. However, a close examination of the Food and Drug Administration's regulation of LSD research shows that research was never prohibited and was supported more than previously recognized. Instead, the decline reflected complex changes in the regulation of pharmaceutical research and development, rather than a simple ban on LSD studies.