American forensic psychiatry was founded in 1838 with the publication of Isaac Ray's Treatise on the Medical Jurisprudence of Insanity. Ray's ideas were influential in the early history of forensic psychiatry but were overlooked in the formulation of the M'Naghten Rules in England, an early parliamentary effort to define criteria for the insanity defense. in the mid-1800s, asylumbased psychiatrists formulated model laws addressing involuntary commitment and debated the definition of mental illness for legal purposes. in the late 1800s, courts became interested in findings of brain pathology in insanity defense cases, and neurologists joined psychiatrists as expert witnesses. Beginning around 1950, increased judicial activism led to new standards for insanity in criminal cases, advances in the civil rights of mentally ill persons, and refinements in the role of expert witnesses. in 1969 forensic psychiatrists established a professional organization, and board certification in the subspecialty began in 1979.