The insanity defense, also known as the mental disorder defense, is a legal defense that can be used by a defendant in a criminal case to argue that they should not be held criminally responsible for their actions due to a mental disorder. The idea behind the insanity defense is that a person who is not capable of understanding the wrongfulness of their actions or controlling their behavior should not be held fully accountable in the same way as a person who is able to do so.
The use of the insanity defense has been controversial, with some arguing that it allows people to avoid responsibility for their actions and others arguing that it is a necessary tool for addressing cases where the defendant's mental state played a significant role in the crime.
The insanity defense has a long history, dating back to ancient Rome and the concept of "mens rea," or guilty mind. One of the most significant landmark insanity defense cases was the 1843 case of Daniel M'Naghten, who shot and killed the Secretary of State's private secretary, believing that he was shooting at the Prime Minister of England. M'Naghten was acquitted by reason of insanity, setting a precedent for the use of the defense in future cases.
Over time, different tests for determining insanity have been developed and adopted by various jurisdictions. The most commonly used test is the "M'Naghten test," which asks whether the defendant was able to understand the nature and quality of their actions and whether they knew that their actions were wrong. Other tests include the "irresistible impulse" test, which asks whether the defendant was able to control their actions, and the "Durham test," which asks whether the defendant's mental disorder was the cause of the crime.
Some states have adopted an "abolismentist" approach, which means that they do not recognize the insanity defense at all. In these states, the defendant is either found guilty or not guilty, with no provision for a finding of not guilty by reason of insanity.
Critics of the insanity defense argue that it is too broad and allows people to avoid responsibility for their actions. They point to cases where defendants have been found not guilty by reason of insanity and then released back into society without proper treatment, only to commit crimes again. Supporters of the defense argue that it is a necessary tool for addressing cases where the defendant's mental state played a significant role in the crime and that it recognizes the fact that people with mental illnesses are often not fully responsible for their actions.
One alternative to the insanity defense that has been proposed is the "guilty but mentally ill" (GBMI) verdict, which allows the defendant to be found guilty but also acknowledges that their mental illness played a role in the crime. Under a GBMI verdict, the defendant would receive both punishment for the crime and treatment for their mental illness although treatment is infrequently provided.
The insanity defense is a complex legal issue with no easy answers. It is clear that the mental state of a defendant should be taken into account when determining their criminal responsibility, but the question of how to do so in a fair and just way remains a subject of debate. What is certain is that people with mental illnesses deserve appropriate treatment and support, and that the criminal justice system has a role to play in ensuring that they receive it.