insanity, 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).

The Columbia Encyclopedia, 6th ed. Copyright© 2014, The Columbia University Press.

Insanity: Selected full-text books and articles

Suffering Insanity: Psychoanalytic Essays on Psychosis
R. D. Hinshelwood.
Brunner-Routledge, 2004
A Reference Companion to the History of Abnormal Psychology
John G. Howells; M. Livia Osborn.
Greenwood Press, vol.1, 1984
A Reference Companion to the History of Abnormal Psychology
John G. Howells; M. Livia Osborn.
Greenwood Press, vol.2, 1984
Madness and Democracy: The Modern Psychiatric Universe
Marcel Gauchet; Gladys Swain; Catherine Porter.
Princeton University Press, 1999
Evil or Ill? Justifying the Insanity Defence
Lawrie Reznek.
Routledge, 1997
Lunacy, Law, and Conscience, 1744-1845: The Social History of the Care of the Insane
Kathleen Jones.
Routledge & Kegan Paul, 1955
Mental Condition Defences in the Criminal Law
R. D. Mackay.
Clarendon Press, 1995
The Insanity Defense: A Critical Assessment of Law and Policy in the Post-Hinckley Era
Rita J. Simon; David E. Aaronson.
Praeger, 1988
Insanity, Institutions, and Society, 1800-1914
Joseph Melling; Bill Forsythe.
Routledge, 1999
Media Madness: Public Images of Mental Illness
Otto F. Wahl.
Rutgers University Press, 1995
Love's Madness: Medicine, the Novel, and Female Insanity, 1800-1865
Helen Small.
Clarendon Press, 1998
Insanity as Redemption in Contemporary American Fiction: Inmates Running the Asylum
Barbara Tepa Lupack.
University Press of Florida, 1995
The Madness of Epic: Reading Insanity from Homer to Statius
Debra Hershkowitz.
Clarendon Press, 1998
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