Ignorance or Mistake


Fundamentals of Criminal Law

Adam J. McKee, Ph.D.

Jack Brown, Ph.D.


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Ignorance or mistake is of two types. Mistake of fact means that circumstances were not as you thought. Mistake of law means that there was an error in your understanding of the law.

A mistake of fact can be a defense under two circumstances:

  • The statute making the act a crime specifically provides for the defense
  • A mistaken belief of fact provides for a justification

A mistake of law is generally no defense unless the mistake is due to some official version of the law (statutes, high court decisions, administrative interpretations such as by the state AG’s office) that is incorrect.  Mistakes of law other than the existence or interpretation of a specific statute can be used to disprove specific culpable mental states.  Mistakes of law arising from other legal sources that are not official statements of the law generally are not sufficient to provide a defense.  For example, Incorrect advice from a licensed attorney cannot form the grounds for a mistake of law defense.

Mistake of fact is far more likely to provide a viable defense than mistake of law. If the facts as the defendant believes them to be nullify the intent element for the crime under consideration, the defendant can assert a mistake of fact as a defense.  Note that mistake of fact is generally not a defense to strict liability crimes because intent is not an element of such offenses.  A defendant, for example, is not likely to prevail in traffic court by claiming that he mistakenly believed the speed limit to be different from what it actually was.

Modification History

File Created:  07/17/2018

Last Modified:  07/17/2018

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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