In general, any error or misconception.
In contract law, a situation where the parties did not mean the same thing when they agreed to a term or provision. Also, when at least one contracting party held a belief that was factually or legally false. As a result, the contract may be subject to modification or rescission.
In criminal law, a defense that claims either a misconception of the law or some fact. The defense of mistaking the law almost never succeeds. Mistakes of fact can work as a defense more often, especially if they are reasonable.
Definition from Nolo’s Plain-English Law Dictionary
1) An error which causes one party or both parties to enter into a contract without understanding the obligations or results. Such a mistake can entitle one party or both parties to a rescission (cancellation) of the contract. A mistaken understanding of the law (as distinguished from facts) by one party only is usually not a basis for rescission. 2) An error as to facts or law made by a judge. Such errors may be harmless (not meriting a reversal) or material (a reversible error).
Definition provided by Nolo’s Plain-English Law Dictionary.
August 19, 2010, 5:20 pm