Insanity Defense Reform Act (1984)
as a result of mental illness, the defendant lacks the capacity to appreciate the nature and quality or wrongfulness of the act
M'Naghten:
- the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong