The Four Tests for Insanity

The Four Tests for Insanity

There are four different insanity tests that have been used by U.S. Courts over the years. They are The M’Naghten Rule, the “Irresistible Impulse” or “Control” Test, the “Product” Test, and the Model Penal Code "Substantial Capacity" Test. Note that this is a brief description of the tests and does not address whether any of them are flawed.

The M’Naghten Rule:

The first of these, The M’Naghten Rule, has its foundations in English Common law from the attempted assassination of the British Prime Minister, Robert Peel in 1843 by Daniel M’Naghten. In M'Naghten's case, instead of shooting the Prime Minister, M’Naghten’s shot missed Peel and hit his secretary Edward Drummond, who died a few days later. M’Naghten was acquitted of the crime based on insanity. Due to the importance of the victim and the intended victim, there was a firm public outcry, and the House of Lords was required to come up answers for the basis of their decision. These answers were amended to the original decision and are considered to be as if they were part of that decision. The test is as follows:

“To establish a defense on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was laboring 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.”

It is important to note that the M’Naghten rule refuses to recognize volitional or emotional impairments, and instead recognizes the cognitive element as the singular cause of conduct.

The “Irresistible Impulse” or “Control” Test

 In a response to some of the criticisms on the M’Naghten rule, the state of Alabama created a test based on “Irresistible Impulse” in the case of Parsons v. State 81 Ala. 577 (1887). In Parsons, the defendants had been convicted of the murder of Bennett Parsons, by shooting him with a gun; one of the defendants was the wife and the other the daughter of the deceased. The defense set up in the trial was the plea of insanity by showing that the daughter was an idiot, and the mother and wife a lunatic, subject to insane delusions, and that the killing on her part was the offspring and product of those delusions.

“[I]f a person commit a homicide knowing it to be wrong, but do so under the influence of an uncontrollable and irresistible impulse, arising not from natural passion, but from an insane condition of the mind, he is not criminally responsible. “81 Ala. 591

 Wrongness plays no part in this test, just whether or not the governing power of the mind has been destroyed.

The “Product Test”

In 1954, the Court of Appeals for the District of Columbia declared that, “an accused is not criminally responsible if his unlawful act was the product of mental disease or mental defect.” Durham v. United States, 94 U.S.App.D.C. 228.  This case originated from the Supreme Court of New Hampshire in State v. Pike, 49 N.H. 399 (1869), but had not been largely adopted due to the supremacy of M’Naghten. In addition, this test had not defined “product” and thus is vague. In addition, there was much dispute over this test because it expanded the defense of legal insanity more so than the M’Naghten or “Irresistible Impulse Tests.”

This test was a precursor to the Model Penal Test. 

Model Penal Code “Substantial Capacity” Test

Due to the substantial criticism that was made against the above tests due to their strictness, the American Law Institute created the “Substantial Capacity” Test in order to broaden the scope of the insanity defense.

This test relieves the defendant of responsibility under two circumstances:

(1) When, as a result of mental disease or defect, the defendant lacks substantial capacity to appreciate the criminality [wrongfulness] of his conduct; (2) When, as a result of mental disease or defect, the defendant lacked substantial capacity to conform his conduct to the requirements of law.

 The use of “appreciate” rather than “know” conveys a broader sense of understanding than simple cognition. Additionally, the terms “mental disease or defect” do not include an abnormality manifested only by repeated criminal or otherwise anti-social conduct.

Note:

The M’Naghten Rule is still primarily used today. It seems that whenever courts start to move away from the M’Naghten Rule someone tries to assassinate a prime minister or a president and then claim insanity. Some states do not recognize an insanity defense.

P.S. Badly referenced and formatted I know, but I wanted to focus on getting an actual post out rather than creating a work of art.