Insanity: A Legal and Cinematic Diagnosis

The term "insanity" has been retired from medical nomenclature for about 100 years. Formerly interchangeable with the legal term, implying unsoundness of mind, it persists as a legal determination, mainly in criminal matters. However, the most prevalent uses of "insanity" are in colloquial speech and media. We track "insanity" in medical and legal parlance, reasons for its disappearance from psychiatry, and its persistence in popular culture. During the 19th century, specific types of legal insanity fell out of favor, especially "moral insanity," referring to irresistible impulses. The term persisted, for example, in some civil cases and in criminal cases, both denoting lack of capacity. In America, early 20th century focus on disease classification and nomenclature shifted from catchall terms (such as insanity, dementia, mania, and idiocy) to medical labels (psychosis and neurosis). Psychiatrist William Alanson White led the movement to change nomenclature. In 1921, the American Journal of Insanity became the American Journal of Psychiatry. By the time White was the American Psychiatric Association president in 1925, the medical use of "insanity" had been replaced in textbooks by progressive terminology. However, variations on "insane," suggesting loss of reason without diagnostic specificity, have become a staple among film tropes.