LAW 535-001 – Criminal Law

M'Naghten Test


The M'Naghten test, also known as the cognitive test, says that a person is not guilty by reason of insanity when he, at the time he committed the act:

  1. Had a mental defect
  2. Which either:
    1. Prevented him from knowing the nature and quality of the act he was doing or
    2. From knowing that what he was doing was wrong.
      • Wrongfulness

        Wrongfulness can be understood in one of two ways:

        1. Illegal
        2. Morally wrong
          • Moral wrongfulness can also be determined subjectively or objectively:
            • The objective standard asks whether the actor understood his actions violated society's view of morality.
            • The subjective test asks whether the actor was able to understand that his actions violated his own personal moral code.