M'Naughten test

M'Naughten test

Forensic psychiatry The most popular test for defining a person as insane under the law, which will find a defendant insane if she had a diseased mind that caused a defect of reason, such that when she acted, she either didn't know the act was wrong or didn't understand the nature and quality of her actions. See Insanity defense. Cf Durham rule, Irresistible impulse test, Substantial capacity test.