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Related to Legal insanity: Insanity defense, insanity plea


mental disorder of such severity as to render its victim incapable of managing his affairs or of conforming to social standards. Today, the term insanity is used chiefly in criminal law, to denote mental aberrations or defects that may relieve a person from the legal consequences of his or her acts. The case of Daniel McNaughtan, who was found not guilty by reason of insanity after making an assassination attempt on British prime minister Robert Peel (1834), gave rise to the modern insanity defense used in many Western nations today. In the United States, the 1954 case of Durham v. the United States led to the establishment of new rules for testing defendants. Today, psychologists may perform tests to determine whether or not the defendant is mentally stable. Such tests try to ascertain whether or not a defendant can distinguish right from wrong, and whether or not he acted on an "irresistible impulse." John Hinckley's assassination attempt on Ronald Reagan (1981) became another landmark in the history of the insanity defense. The court's initial verdict of "not guilty by reason of insanity" generated public outcry and renewed interest in the verdict of "guilty but mentally ill," which is permissible in some states. This verdict allows defendants deemed mentally ill to be hospitalized but requires them to carry out a reasonable prison sentence as well. In 1983, the Supreme Court ruled it permissable to keep a mentally ill defendant hospitalized for a term longer than the maximum sentence for the crime with which the defendant was charged. Many have contended that the insanity defense is nothing more than a legal loophole, allowing serious criminals to escape imprisonment. In fact, the plea is rarely employed in the United States, and it is estimated that less than 1% of defendants have used it successfully. Recent years have seen the restrictions surrounding insanity defense considerably narrowed, with the sole criteria for a successful plea being the determination of whether or not the defendant knew he was breaking the law.


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); S. N. Vinocour, Nobody's Child: A Tragedy, a Trial and a History of the Insanity Defense (2020).

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Any mental disorder.
In forensic psychiatry, a mental disorder which prevents one from managing one's affairs, impairs one's ability to distinguish right from wrong, or renders one harmful to oneself or others.
Term previously used to indicate mental disorder; no longer used in medical contexts.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. relatively permanent disorder of the mind; state or condition of being insane
2. Law a defect of reason as a result of mental illness, such that a defendant does not know what he or she is doing or that it is wrong
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
addition to the popularity of the more expansive test for legal insanity
under the Act bears no direct correlation to legal insanity, or even to
Breyer opted out of some parts of the majority opinion) in the 6-3 ruling, said the Constitution's guarantee of due process did not prevent Arizona from lopping off one of two prongs of a definition of legal insanity known as the M'Naghten rule.
(107) "[I]mpermissibly allow[ing] juries to avoid finding a defendant not guilty by reason of insanity in cases in which legal insanity appears justified" (108) is an inappropriate means of reducing insanity acquittee recidivism.
affirmed the right of the state to formulate the applicable test of legal insanity. In so doing, however, the [C]ourt measured the law under due process standards, concluding that the irresistible impulse extension of [the] traditional [extrinsic] insanity test was not "`implicit in the concept of ordered liberty.'" The court thus seemingly accepted the proposition that the [extrinsic] insanity defense, in some formulation, is required by due process.
Professor Robinson's interesting and scholarly book is the first to deal with the history of legal insanity from Ancient Greece and Rome to modern times.
Slovenko writes at length about what mental illness means and what types of mental illness qualify under the test for legal insanity. He points out that the vast majority of people considered legally insane suffer from severe psychiatric illnesses if not psychotic disorders.
recommends various changes in the rules of the game, such as a ban on plea bargaining; a ban on psychiatric testimony on the "state of mind" of the accused at the time of the crime; replacement of the Miranda and search-and-seizure exclusionary rules; repeal of the legal insanity defense; capital punishment as the standard penalty for premeditated murder; repeal of drug laws; greater use of private incentives and contractors to administer criminal justice; more work for prisoners; more prison space; truth-in-sentencing for violent criminals (serve 85 percent or more of sentences); juvenile records available for adult sentencing; restitution actually enforced; and parolees supervised intensely by armed officers.
First, it addresses briefly the common misunderstanding about when a new syndrome defense is in fact being used and considers why new syndrome claims are raised when it appears that standard doctrinal approaches, such as the negation of mens rea and legal insanity, are available.
Examination and argument distinguished between legal insanity and medical insanity.
Very little is known about patients who have been the subject of long-term detention as a result of a finding of unfitness to plead or legal insanity. In order to discover more about such patients permission was sought to examine Home Office files on all those who had been detained for 15 years of more up to December 1988.

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