What Is Mistake of Fact, and How Can This Defense Help Your Case?

mistake of fact defense

What Is Mistake of Fact, and How Can This Defense Help Your Case?

Mistake of fact is a defense that can be used in Arizona if the defendant made an error that led to committing an illegal action. This legal defense revolves around the fact that the defendant made a reasonable mistake, which resulted in an illegal action. It argues that because there was no criminal intent behind their actions, the defendant should not be convicted of a crime. 

Using Mistake of Fact as a Defense

This argument can be used to invalidate claims of criminal intent.

In Arizona, convictions for nearly all felony or misdemeanor crimes require the culprit to have acted with intent, knowledge, recklessness, or criminal negligence. These are considered states of mind, and it is up to the prosecution to prove that the defendant acted within one of these parameters. The defense can use mistake of fact to prove that the defendant only committed the crime because of an innocent error or mistaken belief. 


Jane is tired after work when she gets to the parking lot and is surprised to find her car unlocked. After entering the vehicle she realizes that it is not, in fact, her car. The true owner returns and accuses her of trying to steal their car. Mistake of fact can be used as a defense in her case.

It can also be used to justify acts of self-defense. 

If you committed a criminal act by defending another person, yourself, or your property in an attempt to prevent another crime. Your actions may be justified if you were trying to stop another crime or if you feared for your own safety or that of another person. 


Mark is walking down the street when he hears a woman call for help. He notices a man running with a bag. He trips the man, causing significant injury. However, it turns out the man and woman were student actors filming a scene. The man presses charges against Mark. Mistake of fact could be used as a defense in his case, because he thought he was apprehending a criminal.

Mistake of Fact and Strict Liability Crimes

However, a mistake of fact cannot apply to any situation. It is not allowed as a defense for any of the following crimes:

  • Sexual contact with a minor
  • Driving under the influence (DUI)
  • Traffic offenses

The reason a mistake of fact defense is not applicable in these instances is becasue they are strict liability crimes. In Arizona, this means criminal intent (existent or not) does not matter, the prosecution only needs to prove that the crime was committed. This does not mean you can’t offer an explanation, however, your state of mind is not considered when making a judgment. 

Is a Mistake of Fact the Same as a Mistake of Law? 

No. A mistake of law means you did not know your actions were illegal. A mistake of law is not a defense in Arizona because the law (ARS 13-204) states that ignorance of the law is not considered an excuse for an illegal action. 

If You Need a Defense Lawyer in Arizona, Todd Coolidge Is the Best

A good attorney will work with you to figure out the best way to defend your case. If you need to defend yourself against unwarranted criminal charges, then you need a certified criminal defense attorney. Todd Coolidge has over 25 years of experience in the Arizona justice system and a winning track record. He gives every case the personal attention needed to secure the best outcome. If you are facing criminal charges, contact us today for a consultation.



Images are used under creative commons license – commercial use (4/16/23). Photo by Tingey Injury Law Firm on Unsplash.