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Daniel McNaughtan

Learning Right From Wrong, A Downward Spiral, Insanity Defense, The Mcnaughtan Rules

Born c. 1812 (Glasgow, Scotland)

Died May 3, 1865 (Berkshire, England)


Daniel McNaughtan was tried in 1843 for the murder of a British government official. He was found not guilty by reason of insanity, and his case created a widely used legal precedent known as the McNaughtan Rules. These rules, established by Great Britain's House of Lords, were delivered by Chief Justice Nicholas Tindal (1776–1846), the judge who had presided at McNaughtan's trial. The rules state that: (a) every person is assumed to be sane until proven otherwise; and, (b) it must be clearly proved that at the time of committing the crime, the accused lacked the understanding to know the nature of his act or even that he was doing something wrong. To this day most American state criminal justice systems use a form of the McNaughtan Rules to determine a person's criminal responsibility.

"The test for sanity . . . is not one of whether the accused suffers from any mental disorder or not, but rather of whether his mental state is such that he should fairly be held responsible."

A basic description for the test for a criminal defendant's sanity

McNaughtan's name has seen various spellings over the years, partly because people at that time did not always spell their names the same way in every document. In association with both the man and the rules, McNaughtan has appeared many ways including McNaughton, M'Naghten, MacNaughten, and McNaughtun. Financial records of Daniel's father, along with an 1843 newspaper article bearing the accused signature indicate that the McNaughtan spelling was the one used most by the family.

For More Information


Hall, Kermit, ed. The Oxford Companion to American Law. New York: Oxford University Press, 2002.

Katsh, Ethan M., and William Rose, eds. Taking Sides: Clashing Views on Controversial Legal Issues. Guilford, CT: Dushkin Publishing Group, 2000.

Levinson, David, ed. Encyclopedia of Crime and Punishment. Thousand Oaks, CA: Sage Publications, 2002.

Moran, Richard. Knowing Right from Wrong: The Insanity Defense of Daniel McNaughtan. New York: The Free Press, 1981.

Walker, David M., ed. The Oxford Companion to Law. New York: Oxford University Press, 1980.

Web Site

Pearse, O'Malley. "Psychiatry and the Legal System." The Irish Medical Journal. http://www.imj.ie/news_detail.php?nNewsId=1573&nCatId=24&nVolId=85 (accessed on August 15, 2004).

Additional topics

Law Library - American Law and Legal InformationCrime and Criminal Law