See R. Simon and D. Aaronson, The Insanity Defense (1988); R. Porter, A Social History of Madness: The World Through the Eyes of the Insane (1989).
In criminal law, a disease, defect, or condition of the mind that renders one unable to understand the nature of a criminal act or the fact that it is wrong. Tests of insanity are not intended as medical diagnoses but rather only as determinations of whether a person may be held criminally responsible for his or her actions. The most enduring definition of insanity in Anglo-American law was that proposed by Alexander Cockburn (1843). Many U.S. states and several courts have adopted a standard under which the accused must lack “substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.” Some states have abolished the insanity plea, and others allow a finding of “guilty but mentally ill.” Seealso diminished responsibility.
Learn more about insanity with a free trial on Britannica.com.
Europe's oldest asylum is The Bethlem Royal Hospital of London, also known as Bedlam, which began admitting the mentally ill in 1403. The first American asylum was built in Williamsburg, Virginia, circa 1773. Before the 19th century these hospitals were used to isolate the mentally ill or the socially ostracized from society rather than cure them or maintain their health. Pictures from this era portrayed patients bound with rope or chains, often to beds or walls, or restrained in straitjackets.
In United States criminal law, insanity may serve as an affirmative defense to criminal acts and thus does not need to negate an element of the prosecution's case such as general or specific intent. The states differ somewhat in their definition of insanity but most follow the guidelines of the Model Penal Code. All jurisdictions require a sanity evaluation to address the question first of whether or not the defendant has a mental illness. Most courts accept a major mental illness such as psychosis but will not accept the diagnosis of a personality disorder for the purposes of an insanity defense. The second question is whether the mental illness interfered with the defendant's ability to distinguish right from wrong. That is, did the defendant know that the alleged behavior was against the law at the time the offense was committed. Additionally, some jurisdictions add the question of whether or not the defendant was in control of his behavior at the time of the offense. For example, if the defendant compelled by some aspect of his mental illness to commit the illegal act, the defendant could be evaluated as not in control of his behavior at the time of the offense. The forensic mental health specialists submit their evaluations to the court. Since the question of sanity or insanity is a legal question and not a medical one, the judge and or jury will make the final decision regarding the defendant's status regarding an insanity defense.
In most jurisdictions within the United States, if the insanity plea is accepted, the defendant is committed to a psychiatric institution for at least 60 days for further evaluation, and then reevaluated at least yearly after that.
Today feigned insanity is considered malingering. In a 2005 court case, United States v. Binion, the defendant was prosecuted and convicted for obstruction of justice (adding to his original sentence) because he feigned insanity in a Competency to Stand Trial evaluation.