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Mistake of Fact Defense

Ignorance of factual circumstances or mistake of fact is a defense to some criminal charges if the fact that is mistaken indicates that the defendant lacked a particular mental state essential to the crime charged.

For example, if the defendant honestly believed he was selling sugar to his neighbor, when in fact the substance he was selling was cocaine, then the defendant is entitled to an acquittal of the crime of intentionally selling illegal drugs. In this example, the defendant never intended to sell drugs. Of course, the defendant must demonstrate that his belief was honest.

Mistake of fact is a defense most common to specific intent crimes, such as assault, kidnapping, criminal threats, burglary, theft, etc. These type of crimes require that the defendant specifically intended to commit an act that results in a crime. In essence, if the defendant is under a mistaken belief as to a fact that is required to make his conduct a crime then the defendant is not guilty of that crime. For example, if the defendant honestly, but wrongfully believed that he had permission to use his friend’s vehicle, then the defendant is not guilty of the crime grand theft auto (GTA) because GTA requires that the defendant specifically intend to take a vehicle without permission.

General Intent Crimes: Mistake of fact can, but does not usually, apply to general intent crimes, a general intent crimes a crime that only requires knowledge by the defendant that he or she is engaging in a particular type of conduct which is unlawful. Example of general intent crimes include: DUI crimes, battery, child endangerment, neglect type crimes (elder, child, and animal neglect, etc.), manslaughter, and recklessness conduct type crime (reckless burning, reckless driving, etc.).


Mistake of fact is a defense to general intent crimes only if the defendant actually believed the wrong state of facts (subjective intent) and that belief is reasonable to the average person in the same or similar circumstance (objective intent). For example, if a thirty-year-old defendant engaged in sexual intercourse with a seventeen-year-old girl, and the defendant knew that the girl was only seventeen, then the defendant does not have a true but mistaken belief as to the girl’s age and the defense of mistake of fact may not be available to the defendant on that issue. This is true even if the average person would reasonably believe that the girl was of the age of consent (objective intent).

Note: The defendant’s conduct must be lawful conduct in order for a defense of mistake of fact to be valid. For example, if the defendant wrongfully believed that a victim was already dead, and therefore, the defendant buried the victim which caused the victim’s death, then the defendant is not entitled to use the mistake of fact defense to a charge of murder because the defendant’s conduct would not have been legal even if the victim was actually deceased when the defendant buried him.

Statutory Crimes: In some cases, there is no specific or general intent requirement in order for the crime to be committed. These are known as statutory crimes. Nevertheless, a mistake of fact defense may be available if the defendant’s mistake as to a important fact is honest and objectively reasonable. For example, in an unlawful sexual intercourse case, the defendant’s honest and reasonable belief that the alleged victim was of the age of consent is a valid defense. For this reason, mistake of fact defense is used in many sex crimes cases, including unlawful sexual intercourse (formerly known as statutory rape), oral copulation on a minor, sexual penetration by foreign object on a minor, bigamy, furnishing alcohol to a minor, sodomy of a minor, and more.

Public Policy Exceptions: For public policy reasons, the defense of mistake of fact is not available in certain sex offenses, including the crime of lewd and lascivious act on a minor under the age of fourteen (PC 288(a)-F)). This is true even if the defendant honestly and reasonably believed (objectively) that the minor was at least fourteen years old.


Mistake of Fact as to Consent: A mistake of fact defense is available in sex cases where the defendant honestly believed that he or she had consent to engage in sexual conduct. For example, the lack of resistance can lead to a reasonable belief that the alleged victim consented in a sex crimes case; however, the mistake as to the lack of consent in a sex case must be honest and objectively reasonable.


Note: In sex cases, mistake as fact as to the alleged victim’s age and the alleged victim consent may be treated as separate defenses, but for public policy reasons, neither is a defense to some sex crimes, including lewd and lascivious acts on a minor under fourteen (PC 288(a)-F) and more (See above at Public Policy Exceptions).

Intoxication v. Mistake of Fact: Intoxication may be a defense to criminal conduct, but intoxication and mistake of fact cannot be used together. For example, a defendant may not claim the following: Due to intoxication, the defendant honestly but mistakenly believe a fact, and if that fact existed as the defendant believed, it would negate an element of the offense. In essence, the defendant cannot claim that he believed a fact to be true only because he was intoxicated.

Enhancements: A mistake of fact defense is not available if it is only being used to defend against an enhanced penalty. For example, if the defendant stole jewelry from a jewelry store, but the defendant did not realize the value of the jewelry stolen was extremely high, which caused the district attorney to charge enhanced criminal penalties associated with the high-value theft, then the defense of mistake of fact as to the high-dollar amount of the defendant’s theft does not apply to negate the penalty enhancement. In this example, the theft of the jewelry is a crime and the defendant was only mistaken as to the amount of his theft; therefore, the mistake of fact defense does not apply.

Mistake of Law Compared: Mistake of fact, as a defense, should not be confused with mistake of law (A.K.A. Ignorance of the law). There is no defense of ignorance of the law except in very limited and rare circumstances. For example, a person can be convicted of the crime of possession of a firearm by a convicted felon even if she does not know that it is illegal for her to possess a firearm after her felony conviction. On the other hand, if the defendant truly believed that the firearm in her possession was not an actual firearm, then the defense of mistake of fact may apply.

Common Applications: Mistake of fact is a defense that can apply to many crimes; however, this defense is perhaps most commonly used in the following situations:

  • Murder: In a murder prosecution where the defendant honestly but mistakenly believes a gun was not loaded when it was used to kill the victim (the crime of murder reduced to manslaughter)

  • Statutory Rape: In a statutory rape case where the defendant honestly and reasonably, but mistakenly, believed that the minor was of the age of consent

  • Theft: In a theft case where the defendant honestly but mistakenly believed that he had permission to take or use property that was not his

For more information on the defense of mistake of fact and other defenses to criminal charges call our criminal defense lawyers today. Initial consultations are free and our office is available to answer questions every day of the week. Call today!


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