The U.S. Food and Drug Administration (FDA) oversees most clinical research in the United States, ensuring the integrity of trial data and the safety of study participants - including most recently a number of high-stakes vaccine and drug trials for COVID-19. However, a new Science investigation, which closely evaluated FDA's clinical trial enforcement for the past 11 years, suggests that the agency's enforcement of clinical research regulations is often light-handed, slow-moving and secretive - even for cases where clinical trial practices were deemed dangerous or unlawful. FDA's findings can result in several responses - the most stringent of which can immediately halt or restrict clinical trials in progress or, in extreme cases, disqualify a scientist from clinical research altogether. However, according to the Science investigation, which included a review of nearly 1,600 FDA inspection and enforcement documents for clinical trials, the agency rarely levels sanctions. When it does, follow-ups are either slow or neglected, and cases are frequently resolved based on unverified claims. What's more, FDA's approach to enforcement appears to be getting worse. While the agency issued 99 and 36 warning letters for serious clinical trial transgressions during the first and last three years of the Obama administration, respectively, only 12 were issued during the first three years under President Donald Trump. Disqualifications of egregious offenders also plummeted under Trump. The Science findings provide a cautionary take as FDA oversees numerous fast-moving trials of vaccines and drugs for COVID-19.