Duhaime's Law Dictionary

Idiot Definition:

A person incapable of managing his person or his affairs from birth.

Related Terms: Mentally Ill, Lunatic, Non Compos Mentis, De Non Sane Memorie

A now politically incorrect term distinguishing  a person who is incapable of managing his person or his affairs from birth are supposed to a person who though born with capacity, later becomes incapable a reason of sickness or accident, a lunatic.

In Re Lindsey, Justice Dixon of the Court of Errors and Appeals of New Jersey wrote;

"A return that the party was an idiot, or a lunatic, or non compos mentis, or of unsound mind was sufficient because each of those terms imported such a deprivation of sense as rendered the sufferer unfit for self-control, as well as for the management of his affairs."

Theobald wrote:

"By natural fool or idiot is generally understood an imbecile from birth, or at any rate a person whose development has been arrested at an early age - a congenital idiot.

"A lunatic is a person who having once had his wits has lost them....

"Idiocy implied unsoundness of mind from birth or at least from an early age."

Sheppard wrote:

"If an idiot have so much knowledge that he can read or learn by instruction and information of others, or can measure an ell of cloth, or name the days of the week, or beget a child, son or daughter, or such like, whereby it may appear that he has some light of reason, then he is no idiot naturally."

Chitty's Medical Jurisprudence suggests:

"(Idiocy consists in) a defect or sterility of the intellectual power, while lunacy or madness consists in a perversion of intellect."

Idiot was perfectly good legal term in its time. For example, circa 1918, the Penal Code of Iowa included this at §4758:

"If any person ... have such carnal knowledge of an idiot or female naturally of such imbecility of mind or weakness of body as to prevent effectual resistance, he shall be punished...."

In Francke, the Louisiana court wrote:

"The term idiot is applied to those who from original defect have never had mental power.  It is not a loss or perversion of what has once been acquired by a state in which, from the structure of the brain, the individual has never been able to acquire any degree of intellectual power."

William Blackstone's opinion was:

"A man is not an idiot if he hath any glimmering of reason, so that he can tell his parents, his age, or the like common matters."

In the venerable Russell on Crimes, an idiot is defined as:

"A fool, a madman, from his nativity, and one who has never had any lucid intervals; and such a one is described as a person that cannot number twenty, tell the days of the week, does not know his father or mother, or his own age; but these are mentioned as instances only; for whether idiot or not is a question of fact for a jury."

Also in the United States of America, Justice Russell of the Supreme Court of New York wrote, in Bicknell:

"A serious distinction has always been recognized between lunatics and idiots. The one had lucid intervals; the other no power of mind whatever. The term lunatic has broadened to include all insane persons except idiots, as no other distinction seems to be essential."


  • Bicknell v Spear, 38 Misc. 389; also at 77 NYS 920 (1902)
  • Chitty, Joseph, A Practical Treatise on Medical Jurisprudence (Philadelphia: Carey, Lea & Blanchard, 1836)
  • Duhaime, Lloyd, Duhaime's Legal Dictionary
  • Duhaime, Lloyd, Duhaime's Legal Citations & Abbreviations
  • Duhaime, Lloyd, Legal Definition of Insanity
  • Duhaime, Lloyd, Legal Definition of Non Compos Mentis
  • Francke v Francke, 29 La. Ann. 302
  • In re Lindsley, 15 A. 1 and also at 44 N.J. Eq. 564 (1888)
  • Russell, W. O., A Treatise on Crimes and Misdemeanors (Philadelphia: T. & J. W. Johnson & Co., 1857), page 5
  • Sheppard, Gr. Ab. tit, Idiot; quoted in Heard, Franklin Fiske, Curiosities of the Law Reporters (Boston: W.S. Bartlett, 1871), page 196.
  • Theobald, H. S., The Law Relating to Lunacy (London: Stevens & Sons, 1924), page 2-3 (note 1)

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