Just saying that "it was a mistake" might not save you from a criminal charge, but there are cases in which you can use a mistake as a criminal defense. Here are the two main ways in which you can use mistakes to defend criminal charges.

Mistake of Law

To use the mistake of law defense, you have to prove that you misunderstood the law or were not aware that an existing law made your actions illegal. This defense is rarely successful because it is the responsibility of the public to know the laws of their jurisdictions.

Similarly, most criminal acts are common knowledge, and it would be difficult for a person to claim that they are not aware of their crime. For example, if you have been charged with a DUI (driving under the influence), you can't claim that you didn't know that driving while intoxicated is a crime.


The mistake of law defense is, thus, may only be applied in a few unique cases. Consider an example in which the speed limit at a dangerous section of the highway has been designated at 40mph, but the relevant authorities have not put the relevant signs. In such a case, you may be able to use the mistake of law defense if the police arrest you for driving over 40mph at that section of the road.

Mistake of Fact

In its simplest form, this defense claims that you did not intend to undertake your alleged criminal act. A mistake of fact might apply if you can prove the following:

  • You never intended to commit the crime
  • You were ignorant of the law
  • You did not know the difference between what was right and wrong at the time of your alleged criminal act.

There are only a few specific situations in which this defense may work. These are situations in which intent to commit a crime is critical.


Theft, in all its various forms, is a classic example of a crime that the mistake of fact defense can defend. Say you have been charged with shoplifting a designer bag at a high-end store, but you also entered the store with a similar bag and you picked up the wrong bag during the exit. If there is proof (such as CCTV footage) of you entering the store with a similar bag, you may be able to use the mistake of fact defense to avoid the shoplifting charges.

It is not easy to succeed with either of these two forms of defenses. The mistake defense is best left to a criminal lawyer if the lawyer is convinced it is the right approach to take. 

For more information on criminal defense, contact a law firm like Shefferman Law.