Under the M'Naughten Test, what must a defendant demonstrate?

Under the M'Naughten Test, the primary focus is on the defendant's mental state at the time of the offense, specifically their understanding and awareness regarding the nature of their actions. For a defendant to successfully invoke the insanity defense under this test, they need to demonstrate that, due to a severe mental disease or defect, they were unable to understand the nature of their actions or comprehend that what they were doing was wrong.

This framework is grounded in the principle that moral culpability should not apply to individuals who, due to their mental condition, lack the capacity to differentiate between right and wrong.

In essence, the M'Naughten Test is designed to assess the cognitive ability of defendants in relation to their awareness of the wrongfulness of their actions, rather than focusing on intent, legal representation, or the absence of mental illness. By meeting the criteria set by this test, the defendant can be found not guilty by reason of insanity.