M'Naghten test

Jurisdictions that follow the M'Naghten test provide that a party is legally insane and relieved of responsibility for his or her criminal act only if at the time he or she committed the act, he or she was laboring under such a defect of reason, from disease of mind, as not to know the nature and quality of the act he or she was doing; or if he or she did know it, that he or she did not know that what he or she was doing was wrong.

See also . . .