38 CFR § 3.354 - Determinations of insanity.
(a)Definition of insanity. An insane person is one who, while not mentally defective or constitutionally psychopathic, except when a psychosis has been engrafted upon such basic condition, exhibits, due to disease, a more or less prolonged deviation from his normal method of behavior; or who interferes with the peace of society; or who has so departed (become antisocial) from the accepted standards of the community to which by birth and education he belongs as to lack the adaptability to make further adjustment to the social customs of the community in which he resides.
(b)Insanity causing discharge. When a rating agency is concerned with determining whether a veteran was insane at the time he committed an offense leading to his court-martial, discharge or resignation (38 U.S.C. 5303(b)), it will base its decision on all the evidence procurable relating to the period involved, and apply the definition in paragraph (a) of this section.