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Posted on March 19, 2019 in Firm News

Why Can Insanity Be Used as a Defense in Court?

Many Americans may know that insanity can be a viable defense against some criminal charges, but media portrayals of these situations may skew their ideas of how this legal statute actually works. The insanity defense has roots in British law reaching back to 1581, when the court stated that a “madman or lunatic” could not be held accountable for actions taken when in an unstable frame of mind. The court system uses different language today to identify defendants that qualify for the insanity defense, but the premise is generally the same as it was more than 400 years ago.

How Do You Prove Insanity?

Different court systems throughout the country use different standards to determine a defendant’s eligibility for the insanity defense.

  • The M’Naghten Rule requires proving the defendant had no ability to distinguish between right from wrong or did not understand what he or she did due to a clinically diagnosed mental health illness.
  • The Irresistible Impulse Test checks if a defendant was unable to control his or her impulses due to a clinically diagnosed mental health illness.
  • The Durham Rule requires proving the defendant’s criminal action was the result of a “mental defect” and not from conscious wrongdoing regardless of whether the defendant has had a clinical diagnosis. Only New Hampshire uses the Durham Rule to determine insanity in a criminal case.
  • The Model Penal Code Test for Legal Insanity requires proving the defendant was unable to act within the confines of the law or failed to understand the severity of his or her actions due to a “mental defect.”

Building a defense on any of these tests will often require testimony from expert witnesses with relevant professional backgrounds. For example, mental health treatment professionals may testify as to whether a defendant’s violent behavior and observable symptoms indicate a mental health condition that would constitute a “mental defect” for the purposes of legal defense. Other professionals may also testify as to whether a defendant’s clinically diagnosed mental health condition could lead to the behavior observed or if other people with the same condition have engaged in similar behavior, setting a precedent for an insanity defense.

Insanity Defense in Different States

Four states do not allow the insanity defense: Kansas, Idaho, Montana, and Utah. These states with the exception of Kansas instead issue a “guilty but insane” verdict. Kansas does not recognize insanity as an acceptable criminal defense, nor does Kansas allow for the distinction between “guilty” and “guilty but insane” verdicts.

Most states refer to the Model Penal Code Test or the M’Naghten Rule to determine the validity of an insanity defense, but some may also use a combination of one of these tests with the Irresistible Impulse Test to test an insanity defense.

Penalties After an Insanity Plea

Most states allow for insanity pleas to ensure those suffering from mental health disorders do not injure themselves or anyone else, and their punishment for committing crimes while in unstable states of mind usually involves rehabilitation and counseling. For example, a person who commits a crime while meeting the legal definition of insanity may need to spend time in a mental health institution rather than prison.

Insanity is a nebulous term, and some people may experience ongoing mental health issues while others experience acute episodes of insanity due to extreme stress, substance abuse, or other specific factors. It may be difficult to prove insanity or temporary insanity after a criminal act, and a defense attorney can help you determine whether insanity is a viable defense in your case.

Be prepared; an insanity plea does not completely release you from liability for your actions, and while your sentence may be lighter than it would have been otherwise, an insanity plea will likely mean long-term institutionalization and extensive supervision following the verdict.