A mistake of fact is a quasi criminal defense in which a defendant attempts to limit their liability for a crime based on an incorrect assumption of fact rather than criminal intent. Certain mistakes of fact can eliminate culpability for a crime if they are genuine mistakes and had the incorrect assumption been true, the act itself would not be a crime.

A common mistake of fact involves property ownership such as attempting to enter a car that you mistake for your own vehicle or grabbing a suitcase from the baggage claim of an airport that is identical to yours. In either case, you are not guilty of theft as long as you correct the mistake after its realized.

What is a Mistake of Law?

Mistakes of law are different from mistakes of fact. Mistakes of law occur when the person did not know that their actions were illegal.

For example, an owner walks their dog off its leash in the city park not realizing that a city ordinance exists prohibiting unleashed dogs. Many of us have heard the saying: “ignorance of the law is no defense.” That certainly rings true in U.S. law.

When is a Mistake of Fact a Legal Defense?

Mistakes of fact are not legal defenses per se, rather they are opportunities to eliminate the prosecution’s ability to prove certain elements of a crime. Most crimes have either a general intent or specific intent requirement.

This means that the prosecution must prove that the defendant intended the act that was illegal. If the defendant did not have the criminal intent due to a mistake of fact, than they may be found not guilty. For example, a store owner stocks their shelves with sealed one pound bags of flour that they receive from a supplier.

Unbeknownst to the owner, the supplier also works in the heroin drug trade and accidentally sent a pound of heroin in one of the flour packages to the store. The store owner had no idea heroin would be in the package and sold it to a customer.

The store owner is not likely to be convicted for the illegal sell of heroin because they never had the intent to sell heroin; they intended to sell flour.

However, if the store owner is in the business of selling heroin and cocaine and accidentally sells heroin to a client who wanted to purchase cocaine, then the store owner’s mistake that they sold heroin rather than cocaine will not protect the owner from prosecution. The mistaken criminal intent of selling one illegal substance does not negate the actual criminal intent of selling the other.

What About a Fact in Dispute?

A fact in dispute is common between prosecutors and defendants and is different from a mistake of fact. Facts in dispute are usually the subject of a trial where one side argues one fact occurred and the other argues that something else actually occurred.

Disputes such as the amount of money, merchandise or illegal substances is frequently disputed between sides during a trial or negotiation. Another in dispute may be the identity of the person seen committing the crime; a prosecutor says it was the defendant and the defendant may deny it was them.

Facts in dispute are generally not appealable. Usually only mistakes of law or errors in law committed by a judge are appealable.

Do I Need a Criminal Lawyer to Help Me?

Yes. If you have been accused of a crime, you should consult with a criminal defense lawyer. They can explain your rights, assist in investigating any defenses you may have including a mistake of fact, and represent you in court.