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Five Surprising Facts about Insanity Defenses

Insanity defenses tend to provoke a lot of controversy, especially when a high-profile case ends with the accused being found not guilty because of a mental impairment. For some people, the fact that a person who clearly committed a crime could nonetheless be found not guilty of it is deeply troubling. However, the insanity defense has existed for centuries and is designed to ensure that defendants who are incapable of understanding what it is they may have done are not punished because of an action that was beyond their control. While the insanity defense sparks lots of debate, it is also highly misunderstood. Below are just four aspects of insanity defenses you may not know about.

Insanity defenses are very rare

While they certainly garner a lot of media attention, the fact is that using the insanity defense is extremely rare. Numerous studies have been conducted into how common insanity pleas are and almost all of them have found that such pleas are made in less than one percent of cases. In fact, a 1991 study found that not only were insanity defenses made in less than one percent of cases at the county level, but that such defenses were successful only about a quarter of the time.

Not all states offer the insanity defense

There are three states where it is not possible use the insanity defense. Those states are Idaho, Montana, and Utah. However, while these states do not allow the insanity defense, defendants there must still be found mentally competent to stand trial, meaning that they understand the charges against them. Furthermore, in those three states defendants can still argue that they are not guilty if a mental condition made it impossible for them to have intended to commit the crime they are accused of.

Insanity defenses can lead to longer confinements

While some people get upset that a person who is acquitted of a crime by reason of insanity is viewed as “not guilty” in the eyes of the law, it is important to point out that such an acquittal does not necessarily translate into freedom back into society. In fact, the American Psychiatric Association has studied this issue and points out that those who are acquitted by reason of insanity are, on average, confined to an institution for longer periods than those found guilty of similar crimes are incarcerated in prison.

Psychiatrists don’t decide if a person is insane

Psychiatrists and psychologists play a big role in criminal cases involving insanity defenses. That is because these professionals are considered expert witnesses who can offer testimony to help determine whether or not the defendant is insane. However, the ultimate decision about whether or not a defendant is insane does not lie with these professionals, but rather with the jury and judge, who must take the evidence provided by expert witnesses into account when rendering their verdicts.

Insanity defenses are often a hot topic in the press, but unfortunately much of the controversy fueling the subject is driven by assumptions that are not always backed up by facts. As the above article shows, the insanity defense, while controversial, is a rarely used and misunderstood defense designed to ensure that the justice system is fairly administered.


This article contains general legal information but does not constitute professional legal advice for your particular situation. The Law Dictionary is not a law firm, and this page does not create an attorney-client or legal adviser relationship. If you have specific questions, please consult a qualified attorney licensed in your jurisdiction.

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