A test for the “insanity defense” in criminal law cases under which a defendant is not responsible for his or her criminal act upon proof that at the time of commission of the act, he or she was laboring under such a defect or reason from a disease of the 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, defendant did not know that what he or she was doing was wrong.

The term “disease of the mind” includes all mental abnormalities, but not a psychopathic personality.

M’Naghten Test is the majority rule.

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