According to a Nov. 20, 1945 memorandum addressed to Brigidar-General Wm. L. Mitchell, General Secretary for the International Military Tribunal [Nuremburg Trials], Cameron examined Rudolph Hess on Nov. 15 and 19, 1945 (Rees 1947, p. 218). The four signatories to the memorandum were Cameron, Dr. Jean Delay, Col. Paul L. Schroeder, M.D., a U.S. Army neuropsychiatric consultant, and Dr. Nolan D. C. Lewis of Columbia University. Lewis was an early supporter of both Sakel's insulin coma therapy (ICT) and Kalinowsky's electroconvulsive therapy (ECT) treatments (Shorter & Healy 2007, p. 77). The April 27, 1945 article in The New York Times alludes to "irreconcilables" and their "permanent internment," but no mention is made of giving ECT to 12-year-old Nazis. Maybe such a suggestion was put forth by Cameron, the 1944-1945 Columbia meetings likely produced many different ideas and approaches to the problem of reintegration, but without an exact citation further speculation would be counter-productive. As that memorandum was introduced into evidence Nov. 24, 1945 at Nuremberg (the signatories were not required to be present and, indeed, had already begun to return to their respective home countries), it stands as significant that in the official commission appointment (U.S. 1946, p. 98), the list names three Russians, three Brits, then introduces "Dr. Nolan D. C. Lewis, assisted by Dr. D. Ewen Cameron and Col. Paul Schroeder, M.D." The tenth and final name is "Professor Jean Delay," a French psychiatrist from the School of Medicine at the University of Paris. By this account, Lewis headed the American medical and psychiatric team and brought Cameron along for his expertise in memory.

Delay's international work started very early, in 1945, when he was nominated as an expert at the Nuremberg trial, during which he examined Rudolph Hess and Julius Streicher. In 1950 he organized, in collaboration with Henri Ey, the first World Congress of Psychiatry in Paris. One of the aims of that congress which was attended by 2,200 participants from 52 different countries was to bring together psychiatrists from France and Germany, only 5 years after World War II ended. He became the first president of the Association for the Organization of World Congresses in Psychiatry, which was the parent association of the World Psychiatric Association.

Although Delay's works on psychopharmacology do not constitute the major part of his scientific contribution, they remain the most famous because of their scientific level as well as their topicality. Jean Delay invented the word "psychopharmacology" along with a whole field of research on psychological and behavioral modifications induced by drugs such as LSD, mescaline, and psilocybin.