[History of psychiatry and the criminally insane in Japan].

This paper illustrates how insane offenders were perceived and treated at the turn of the 20th century, focusing on legal reforms. In accordance with overall reorganization of legal systems after the Meiji Restoration in 1968, the Criminal Law of 1880 stipulated criminal responsibility, ruling that "a person, who was unable to discriminate right and wrong because of loss of mental capacity at the time of committing crime, shall not be punished." Article 39 of the current Criminal Law, which was enacted in 1907, redefined criminal responsibility, to say that "an incompetent person shall not be punished; a person with diminished competence shall be given a mitigation of punishment." Meanwhile, the Law for the Custody for Insane Persons of 1900, which was the first law dealing with the mentally ill, aimed to establish strict regulations with regard to the custody of the insane. However, neither of these laws did not provide any procedures for subsequent management of persons acquitted because of insanity. Under the social changes in the early decades of the 20th century, concern about dangerousness of the criminally insane was intensified. In connection with reform of the Criminal Law, several plans for the management of the criminally insanes were formulated. The author examines these circumstances, referring to the current debate on the management of mentally ill offenders.