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.
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follow the "M'Naughten test," named for the historically
of the M'Naughten test. (32) The Model Penal Code recommends a
735 (2006), in which the Supreme Court upheld the constitutionality of an Arizona statute that removed the cognitive incapacity element or second prong of the M'Naughten test. In so doing, the Supreme Court stated that it had never held that the Constitution mandates an insanity defense, but it had also never held that the Constitution does not require such a test.
Texas uses a form of the M'Naughten test. The insanity defense is set forth in Texas Penal Code (TPC) Section 8.01 in two parts: (a) It is an affirmative defense to prosecution that, at the time of the conduct charged, the actor, as a result of severe mental disease or defect, did not know that his conduct was wrong; (b) The term "mental disease or defect" does not include an abnormality manifested by repeated criminal or otherwise antisocial conduct.
The M'Naughten test restricts psychiatric testimony to the narrow scope of a defendant's cognitive capacity and frequently makes it impossible for expert witnesses to describe the complete picture of the defendant's mental illness (TCPOMIa).