Mistake of Law and Mistake of Fact Defense in a Criminal Case

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 What Is the Difference between Mistake of Fact and Mistake of Law?

In the criminal justice system there are two mistakes that can qualify as a legal defense in particular cases. Those two mistakes are:

  • Mistakes of fact; and
  • Mistakes of law.

It is important to note the legal defenses are not available to be asserted for every criminal charge. However, if a defendant is able to successfully assert a legal defense then the charges that were brought against them will typically be dismissed. This is because in order for a person to be convicted of a crime, the prosecution must prove all of the elements of the crime they have been charged with beyond a reasonable doubt.

When a defendant is able to successfully assert a mistake of fact or mistake of law as a legal defense, then that means that the prosecution will not be able to prove that they had the mental state necessary for the crime in which they committed.

The mental state of a crime, also known as the “mens rea” is the intention or knowledge of wrongdoing that constitutes part of the crime in which a defendant is accused of. As such, a mistake defense could allow the charges brought against the defendant to be dismissed based on a lack of mens rea.

What Is a Mistake of Fact?

As mentioned above, mistake of fact is a legal defense that a defendant accused of a crime may assert to have the criminal charges brought against them either dismissed altogether or have the criminal sentence for the crime reduced.

Specifically, when a defendant asserts a mistake of fact defense, the defendant is asserting that they did not have the intent, or mens rea, necessary to commit the crime because they misunderstood some fact at the time that negates an element of the crime. For example, if a defendant has been charged with a theft crime, but they are able to prove that they reasonably believed at the time that the item belonged to them, or they otherwise had a right to take the item, then that misunderstanding will negate the intent element of the crime of theft.

For theft crimes, a person must generally have intentionally taken an item that belonged to someone else, without that person’s permission, with the intent to permanently deprive them of the item.

As such, if the person has been charged with taking an expensive leather jacket, but they mistakenly believed that jacket belonged to them, because they had a similar jacket that was also at the same location, then it is likely that they will not be charged with the crime of theft based on the mistake of fact. It is important to note that mistakes of fact are not always available as a defense.

When Is a Mistake of Fact a Defense?

Importantly a mistake of fact defense is only available if the mistake is both honest and reasonable. This means that a person accused of a crime cannot later claim that they were mistaken when they actually were fully aware of what they were doing at the time. Similarly, intoxication as a defense is typically not able to be combined with the mistake of fact defense.

As can be seen, a mistake of fact is only a defense in certain situations. For instance, if the person has been accused and charged with a strict liability crime, i.e. a crime where the act of the crime itself is all that is required for the person to be found guilty of the crime, then mistake of fact is not an applicable defense.

What Is an Example of a Mistake of Fact Defense?

As mentioned above, one of the most common examples of a mistake of fact defense is a mistake as to the ownership of property. For example, getting into a person’s unlocked car that strongly resembles that of their own, would likely be a good situation to assert a mistake of fact. Other examples of mistakes of fact include:

  • Mistakes regarding the identity of a person or their characteristics, such as age or gender;
  • Misconceptions regarding the rightful ownership of property or permission to obtain property, such as believing property was one’s own property as noted above;
  • Errors related to locations, street names, or other geographic characteristics; and/or
  • Mistakes regarding weights, measures, and other measurements.

What Is a Mistake of Law?

Similar to a mistake of fact, mistake of law is another legal defense that a person accused of a crime may assert to have the charges brought against them dropped. Specifically, a mistake of law is a legal defense where the person accused of a crime asserts that they did not have the intent or mental state required to commit the crime because they misunderstood the law.

It is important to note that a mistake of law defense is often a difficult legal defense to assert because there is a long standing principle in the criminal system that ignorance of the law is not an excuse for a crime. For example, if a person gets pulled over for going 30 over the speed limit, they cannot simply assert that they were mistaken as to the speed limit and get off the hook for their traffic charge or other criminal charge associated with speeding.

An example of a successful assertion of a mistake of law as a defense may be a person’s honest belief that a state law and statute allowed or gave them permission to do an action, but that mistake of interpretation of the law was not correct. For example, if a local ordinance changed and allowed open carry in a federal building, but the person was caught openly carrying a weapon in a building they mistakenly believed was a federal building, like their local library, that mistake of law may allow the charges brought against them to be dropped.

When Can a Mistake of Law Be a Defense?

Similar to that of a mistake of fact defense, a mistake of law defense is also not applicable in a crime that is a strict liability crime. Because a mistake of law of law defense requires a person accused of a crime to show an honest and good faith assertion that they were mistaken as to the law, the mistake of law defense is also not applicable in situations where a person knew or should have known that what they were doing was a crime.

Additionally, as mentioned above, ignorance of a law is not a defense. Typically, a mistake of law defense is only applicable in very narrow situations, such as:

  • When there is a new law that has not yet been published;
  • When the person accused of a crime relied on a law or statute that was published online or publicly, but then the statute was later overturned or rewritten;
  • When the defendant relied upon a judicial decision or interpretation that was later overruled; and/or
  • When the defendant relied upon the interpretation of the law that was given to them by a public service officer who should have known the law.

Do I Need a Criminal Lawyer?

If you have been arrested or have been accused of a crime, then it is in your best interests to immediately consult an experienced criminal lawyer. An experienced criminal defense attorney will be able to advise you of your legal rights and whether or not any legal defenses, such as mistake of fact or law, is available in your situation.

Additionally, an experienced criminal defense lawyer will be able to ensure that any applicable legal defense is asserted correctly in your case. Finally, an attorney will also be able to represent you at any necessary in person criminal proceeding, as needed.

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