Mistake of law

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.

There is a principle of law that "ignorance of the law is no excuse".[citation needed] In criminal cases, a mistake of law is not a recognized defense, though such a mistake may in very rare instances fall under the legal category of "exculpation". In criminal cases a mistake of fact is normally called simply, "mistake".