United States of America v. Karl Brandt, et al., commonly known as the Doctors' Trial, was the first of the twelve "Subsequent Nuremberg trials" for war crimes and crimes against humanity after the end of World War II between 1946 and 1947. The accused were 20 physicians and 3 SS officials charged for their involvement in the Aktion T4 programme and Nazi human experimentation.

The Doctors' Trial was held by United States authorities at the Palace of Justice in Nuremberg in the American occupation zone before US military courts, not before the International Military Tribunal. Seven of the accused were sentenced to death by hanging, five were sentenced to life imprisonment, four were given prison sentences from 10 to 20 years, and seven were acquitted.

The judges, heard before Military Tribunal I, were Walter B. Beals (presiding judge) from Washington, Harold L. Sebring from Florida, and Johnson T. Crawford from Oklahoma, with Victor C. Swearingen, a former special assistant to the Attorney General of the United States, as an alternate judge. The Chief of Counsel for the Prosecution was Telford Taylor, and the chief prosecutor was James M. McHaney. The indictment was filed on 25 October 1946; the trial lasted from 9 December that year until 20 August 1947.

Twenty of the defendants were physicians and three were SS officials (Viktor Brack, Rudolf Brandt, and Wolfram Sievers), all of whom were accused of being involved in Nazi human experimentation and the Aktion T4 programme of involuntary euthanasia. The physicians came from a variety of civilian and military backgrounds, and some were members of the SS. Other Nazi physicians such as Philipp Bouhler, Ernst-Robert Grawitz, Leonardo Conti, and Enno Lolling had died by suicide, while Josef Mengele, one of the leading Nazi doctors, had evaded capture.

In his opening statement, Taylor summarized the crimes of the defendants.

"The defendants in this case are charged with murders, tortures, and other atrocities committed in the name of medical science. The victims of these crimes numbered in the hundreds of thousands. A handful only are still alive; a few of the survivors will appear in this courtroom. But most of these miserable victims were slaughtered outright or died in the course of the tortures to which they were subjected. For the most part, they are nameless, dead. To their murderers, these wretched people were not individuals at all. They came in wholesale lots and were treated worse than animals."

The accused faced four charges, including:

The tribunal largely dropped count 1, stating that the charge was beyond its jurisdiction.