The Insanity Defense

(by Andrew Garofolo)

Insanity Defense Overview

               The insanity defense was first observed in recorded history in the times of Hammurabi’s Code, which had exemptions for the insane. As time progressed, advancements were made, particularly in England, where the views of the insanity defense changed over time, and led up to the McNaughton Rules. These became the most popular form of the insanity defense, until new standards such as the Irresistible Impulse, the Durham Rule, and the ALI Model Penal code began to emerge in the 20th century. Some other advancements were made after that include the Guilty but Mentally Ill (GBMI) and the Federal Insanity Defense Act of 1984. Pleas for insanity are very rare. Only approximately one percent of defendants plead the insanity defense and only about one fourth of those actually are acquitted by the insanity defense (Knowles, 2000).

The Insanity Defense Timeline

1772 BC Hammurabi’s Code

27 BC–476 AD usage of the insanity defense in the Roman Empire

1313– Good Vs Evil Test

1724– Wild Beast Test

1800– Criminal Lunatics Act

1840– Regina vs Oxford

1843– The McNaughton Rules

1844– The Irresistible  Impulse

1954– The Durham Rule

1962– ALI Model Penal Code Test

1975– Guilty but Mentally Ill

1984– The Federal Insanity Defense Act of 1984



Knowles, Bryan. (2000). Is the Insanity Plea Allowing Criminals to Avoid Justice. Speak     Out. Retrieved from

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