Criminal Law

Question 1

Insanity Defense Tests

Answer 1

M’Naghten test

Under the M’Naghten test, a defendant should be acquitted if:

1. disease of the mind
2. caused a defect of reason
3. such that defendant lacked the ability at time of his actions to: (a) know the wrongfulness; OR (b) understand nature and quality of actions.

Under M’Naghten rule, **loss of control **due to mental illness is no defense.

Irresistible impulse test

Under the irresistible impulse test, a defendant should be acquitted if a mental illness has rendered him unable to control actions or to conform conduct to the law.

Durham test

Under the Durham test, a defendant is entitled to an acquittal if the proof establishes that his crime was the “product of mental disease or defect.” A crime is a “product of” the disease if it would not have been committed but for the disease.

M.P.C. test

Under this test, the defendant is entitled to an acquittal if:

1. he suffered from a mental disease or defect; AND
2. as a result lacked substantial capacity to either (a) appreciate the criminality (wrongfulness) of his conduct; OR (b) conform his conduct to requirements of law.