The Insanity Defense

Insanity. What do you think of when you hear that word? I think of people who are in straight jackets locked away in high security mental institutions. I think of people who commit crimes that are unheard of and almost unspeakable. Insanity is a general term for a semi-permanent, severe mental disorder. The concept of insanity means that “a person lacks the awareness of what he or she is doing and therefore cannot form an intent to do wrong” (www.crimelibrary.com). So what happens when a person commits a crime when they lack awareness or have a severe mental disorder?

The insanity defense is one of defenses available to individuals who have committed an act which the law has declared criminal. A person may be found not criminally responsible for the act with a successful plea of insanity. Since it is very difficult to define abnormal behavior this issue is complicated. If a defendant pleas “not guilty by reason of insanity,” the court must assess his or her mental condition. The issue of insanity is decided by judges or juries who hear the testimony of experts on this issue.

In order for a person to be held criminally liable in the courts, our system demands that he or she must have criminal intent or awareness of the wrongfulness of the act. If a person is mentally ill and unable to distinguish the difference between right and wrong, he or she has no mens rea. This means “he or she cannot be held criminally liable in our society” (Samaha, 2005).

The criteria used to establish a legitimate insanity defense is very rigid. Sometimes the most outrageous behavior committed in public does not satisfy these requirements. In 1886 there was a case in Alabama that changed all of that. The court decided that a person could utilize the insanity defense if he or she could prove that “by a reason of duress of mental disease he had so far lost the power to choose between right and wrong, and to avoid doing the act in question, as that his free agency was at the time destroyed” (Samaha, 2005). This means that even if the defendant knows what they are doing is wrong, they can qualify for a verdict of not guilty by reason of insanity if they suffer from a mental disease that damages their volition. This decision became known as the Irresistible Impulse Test. If someone is able to understand that his behavior is wrong, but still lacks the capacity to stop him from committing the act, it is said that the person has acted on an irresistible impulse. Another standard test that came about was the Durham standard. This said that an individual was legally insane if he “would not have committed the criminal act but for the existence of a mental disease or defect” (www.forensic-evidence.com).

The American Law Institute (A.L.I) established a Model Penal Code in 1970. This was adopted by a number of states who wanted to resolve the conflicts brought on by increasing frequency of the insanity defense. The code was the “middle ground between the harshness of the M’Naghten rule and the leniency of the Durham test” (www.forensic-evidence.com). A.L.I stated that a defendant is not responsible for a criminal offense if “at the time of such conduct, as a result of a mental disease or defect, he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirement of the law.” Even this was too broad and vague for people to define what insanity really is.

The English Lord Bracton established the principle of mental deficiency in human behavior in the 13th Century. In 1581the first insanity plea came about in England with the argument that stated whether or not the defendant had greater ability to distinguish good from evil than a wild beast would. This was the standard insanity requirement of England’s courts for over a hundred years. Any defendant who used this defense had to prove he or she lacked the minimum understanding of a wild animal or infant. It wasn’t until Daniel M’Naghten committed a murder in 1843 that the jurisprudence of the western world was changed.

In 1843 Daniel M’Naghten attempted to shoot a British Prime Minister but shot and killed his secretary instead. This mans defense team said he was insane because of his paranoid ideation and the judge agreed. There was such an outrage of this mans acquittal that the M’Naghten rule came into effect which became the standard for the insanity defense.

That rule stated that an individual might be found not guilty by reason of insanity if he proves he was laboring because of a disease of the mind, under such a defect of reason that the did not know the nature and quality of his act, or if he did know it, he did not know the act was wrong. The rule provided for an affirmative defense to the crime, but also created a very strict standard for determining insanity (Fersch,