Mistake of Fact

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Unlike a Mistake of Law defense, a mistake of fact defense can sometimes exculpate a defendant from criminal liability for his criminal actions where the defense can show that the mistake of fact negated the requisite mens rea of the crime. If mens rea is not an element of the crime, such as in strict liability crimes, the mistake of fact defense is not available.

International Law

The Rome Statute of the International Criminal Court provides for a limited mistake of fact defense. Article 32(1) reads:

“A mistake of fact shall be a ground for excluding criminal responsibility only if it negates the mental element required by the crime.”[1]

The mistake of fact must be shown to negate the requisite mens rea element of an international criminal charge in order to be effective.

Specific Country Applications

Sri Lanka

The Penal Code provides for a mistake of fact defence, excusing criminal liability for an action by a person who in good faith and by mistake of fact believes himself to be either bound by law[2] or justified by law[3] to perform said action. The mistake of fact defence has been used to avoid conviction on statutory offences that do not require a mens rea element, so long as the defendant can put forth sufficient facts to carry his burden of showing an honest mistake of fact in the case.[4]

United States

The U.S. generally allows the defendant to put forth a mistake of fact defense either under common law or through a statute, depending on the jurisdiction.

For specific intent offenses, a defendant can avoid criminal liability if his mistake of fact negates the specific intent element of the crime, specifically if he lacks the intent designated by statute. The burden of proof is on the defense to submit sufficient evidence to show that the mistake of fact negated the requisite mens rea of the offense. For general intent crimes, which require only the intent to act in a certain way regardless of criminal intent, the general rule is that a mistake of fact must be reasonable to excuse criminal liability. Under the legal-wrong doctrine, however, the mistake of fact defense will not work if the defendant’s conduct would still be illegal even if the facts were as the defendant thought them to be. Similar, but less widely accepted, is the moral-wrong doctrine, which disallows a mistake of fact defense if the defendant’s conduct was morally wrong even if the facts were as the defendant thought them to be.[5]

Strict liability crimes, such as bans on toxic dumping or the sale of alcohol to minors, lack a mens rea element. Thus, a mistake of fact defense cannot be asserted to avoid criminal liability for violation of a strict liability crime.[6]

The Model Penal Code § 2.04(1) provides that a mistake is a defense if it negates the mental state required to establish any element of the offense. However, the mistake of fact defense is not available to a defendant who is still guilty of another offense had the circumstances been as he supposed.[7]

See Defenses


  1. Available at http://untreaty.un.org/cod/icc/statute/99_corr/cstatute.htm
  2. Penal Code § 69 (No. 2 of 1883), available at http://www.lawnet.lk/process.php?st=2001Y1V19C&hword=%27%27&path=5
  3. Penal Code § 72
  4. See, e.g., Perera v. Munaweera [1955], NLR 433 of 56, available at http://www.lawnet.lk/docs/case_law/nlr/common/html/NLR56V433.htm
  5. http://www.lexisnexis.com/lawschool/study/outlines/html/crim/crim17.htm
  6. http://legal-dictionary.thefreedictionary.com/Mistake+of+Fact
  7. Model Penal Code § 2.04(1), available at http://law.fordham.edu/assets/Faculty/model_penal_code_selected_sections(1).pdf