ARS § 13-204 – “Mistake of Fact” Defense – Arizona Law

In Arizona, mistake of fact is a legal defense to crimes that require a culpable mental state. The defense is based on the assertion that the defendant’s illegal conduct only happened because he or she made a reasonable and honest mistake, in good faith. The defense is permitted in certain circumstances by ARS § 13-204.

The language of ARS § 13-204 states that:

A. Ignorance or a mistaken belief as to a matter of fact does not relieve a person of criminal liability unless:

1. It negates the culpable mental state required for commission of the offense; or

2. It supports a defense of justification as defined in chapter 4 of this title.

B. Ignorance or mistake as to a matter of law does not relieve a person of criminal responsibility.

Mistake of fact is different from mistake of law. The mistake of law defense claims that the defendant did not know what he or she was doing was illegal. Mistake of law is not a valid defense in Arizona.

1. What is the mistake of fact defense in Arizona?

The mistake of fact defense is the legal argument that the defendant only committed the criminal activity they are being accused of because they acted out of ignorance or a mistaken belief about what was happening.

Arizona’s criminal law, in ARS 13-204, only allows defendants to raise this defense in 2 circumstances:

1. to negate the culpable mental state necessary to commit the crime, or
2. to support a justification defense.¹

In either situation, a reasonable mistake of fact is not an affirmative defense. The defendant’s criminal defense lawyer can raise and present evidence to support it, but it will ultimately be up to the prosecutor to prove that it was not at issue in the criminal case. If the prosecutor does not overcome the evidence of the defendant’s mistake, it can lead to an acquittal.

1.1 Negate a culpable mental state

One circumstance in which the mistake of fact defense can be used is to prevent the prosecutor from proving that the defendant acted with a culpable mental state.

Most crimes in Arizona, and nearly all felonies, require the defendant to act with one of the following culpable mental states for the act to be illegal:

• intent,
• knowledge,
• recklessness, or
• criminal negligence.²

The necessary mental state for a crime is also known as “mens rea.” The phrase is Latin for “guilty mind.” The necessary mental state will depend on the offense. It will be explicitly stated in the criminal statute. Because the defendant’s mental state is an element of the crime, is up to the prosecutor to prove beyond a reasonable doubt.

For example:

• first-degree murder requires proof that the defendant acted with intent and premeditation,³
• second-degree murder requires proof that the defendant acted with intent, but not premeditation,⁴ and
• manslaughter can require proof that the defendant acted recklessly.⁵

Some crimes do not have a mens rea requirement. These are strict liability crimes. Many strict liability crimes are misdemeanors.

Whenever there is a required mental state for the offense, the mistake of fact defense can keep the prosecutor from proving it. By showing that the defendant only acted out of ignorance or due to a mistaken belief about his or her surroundings, a criminal defense attorney can raise reasonable doubts about the defendant’s mental culpability.

For example: On her way out the door of her office, Harriet takes a black umbrella that looks very similar to hers, which she believes is her own, but is actually John’s. John accuses Harriet of theft.

1.2 Support a defense of justification

The mistake of fact defense can also support the defendant’s claim that the crime was justified. A criminal act can be justified if it was done in:

• self-defense,
• defense of a third person,
• defense of property,
• duress,
• necessity, or
• prevention of a crime.⁶

Mistake of fact can support a justification defense by showing that the defendant acted in a reasonable, but ultimately mistaken, belief that his or her conduct was justified.

For example: John hears screaming and sees Klaus pointing a gun at Claire. Believing that he is preventing a homicide or a robbery, John pulls out his own gun and shoots Klaus. Klaus’ gun, however, was actually a toy gun that looked very realistic.

2. How is this different from mistake of law?

Mistake of fact is different from mistake of law in that:

• a mistake of fact has to do with a person’s surroundings, while
• a mistake of law has to do with the person’s understanding of the law.

In Arizona, mistake of fact is a legal defense in certain circumstances. Mistake of law, however, is not a defense.⁷ The general rule is that “ignorance of the law is no excuse.”

For example: Harriet takes John’s umbrella, knowing that it is John’s, but acting in the mistaken belief that it is not illegal to steal things that are worth less than $10.

3. Do these criminal defenses work for strict liability crimes?

The mistake of fact defense does not work for strict liability crimes.

Strict liability crimes do not have a mens rea component to them. The act itself is enough to create criminal liability, regardless of whether the defendant on some level intended to commit it.

Some of the more serious or most common examples of strict liability crimes include:

• driving under the influence (DUI),
• traffic offenses, or
• sexual conduct with a minor.

Because there is no specific criminal intent required for law enforcement to secure a conviction, the defense of mistake of fact will not challenge the prosecutor’s case.

For example: Toby leaves the bar after drinking alcohol and gets pulled over by police. Breath tests show that his blood alcohol content (BAC) was 0.11%, which is over the legal limit. Toby wants to argue that he had a reasonable belief that he was under the legal limit, but DUI is a strict liability crime. The illegal act is having a BAC over the legal limit, regardless of intent.

4. What about rape cases?

Arizona criminal law limits the use of the mistake of fact defense in rape or sexual assault cases.

The mistake of fact defense often sounds like it could be invoked to defend against criminal charges of rape. Defendants may claim that they mistakenly thought that:

• the victim consented to the sexual intercourse, or
• the victim was over the age of consent.

However, the Arizona Supreme Court has held that, when the victim was underage, the only act that required a mental state was the intercourse, itself. This meant that the defendant only had to have a specific intent to have sex with the victim, not have sex with an underage victim. As a result, a mistaken belief that the victim was over the age of consent is not a defense.⁸

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