In criminal trials, persons who, due to mental disorder, are unable to discern between right and wrong in their own actions, or are able to make such discernment but are unable to act on it, are treated as mentally incompetent and may therefore not be punished. Also, persons whose ability to make such discernment or to act on such discernment is extremely limited are treated as mentally deficient persons, and their punishment is mitigated accordingly.
  Under the Law concerning Mental Health and the Welfare of Mentally Disordered Persons(referred to as the"Mental Health and Welfare Law"for the purpose of this Chapter), public prosecutors, the directors of probation offices and the superintendents of correctional facilities shall notify the relevant prefectural governor concerning any person who is mentally disordered or suspected to be mentally disordered. The governor may have the person admitted to a mental hospital or designated hospital established by the prefecture(involuntary admission to mental hospital by the prefectural governor), provided that the result of diagnosis by two or more designated doctors indicates that the person is mentally disordered and poses a risk of injury to him/herself or to others.