Mistake of law is a legal principle referring to one or more errors that were made by a person in understanding how the applicable law applied to their past activity that is under analysis by a court. In jurisdictions that
use the term, it is differentiated from mistake of fact.
What is the difference between mistake of fact and mistake of law?
A mistake of fact is only a defense if it negates a material element of the crime. ... If your mistake of fact makes it such that this or some other element is not present, you have a defense and cannot be convicted. Not only must you mistake of fact negate an element of the crime, it must also be an honest mistake.
A mistake of law is where you are mistaken or ignorant about the law. For example, if you believe that you don't have to come to a complete stop at a "Stop" sign when there are no other cars at the intersection, you have made a mistake of law. Whether there are cars or not, you must come to a complete stop. In almost every case, you will not be allowed to argue that you didn't know or misunderstood the law. That is, it won't be
a defense.
When Can a Mistake of Law Be a Defense?
There are a few very limited circumstances in which a mistake of law can serve as a defense to criminal charges. The circumstances in which a mistake of law can serve as a defense include:
When the law is not published
When you relied upon a statute that was later overturned or held to be unconstitutional
When you relied upon a judicial decision
When you relied upon an interpretation by an appropriate official.
In most states, your reliance on any of the above listed sources must be reasonable. So, if your case is pending appeal, it is not reasonable to rely upon the decision reached so far. Also, it is not a defense to claim that you relied upon an interpretation of the law from your lawyer.
Mistake of Fact
Any mistaken belief other than a mistake of law. Examples include erroneous beliefs about the meaning of some term or about the identity of some person.
In criminal law, a mistake of fact can usually operate as a defense so long as it is reasonable. With crimes that require specific intent, even an unreasonable mistake of fact might work as a defense.
In contract law, a mistake of fact may be grounds for rescinding or modifying a contract. A party that interprets a term one way, but has reason to know that another interprets it differently, should bring the issue to light before the contract is closed. Failure to do this often pushes courts to construe the meaning of the term against the party which had knowledge of the possible mistake.
The doctrine of mistake is a grounds for setting aside a contract, the term “mistake”, in a legal context
retains a much narrower sense than in common usage. ... 'Common' mistake refers to a case in which both parties are mistaken and have both made the same mistake in conjunction with the contract.
