Legal Definitions - Mistake of Law

A Mistake of Law occurs when an individual misunderstands or misinterprets what the law requires or prohibits in a particular situation, even if they correctly understand the underlying facts. It is a misunderstanding of the legal consequences of one's actions or circumstances, rather than a misunderstanding of the facts themselves.

Generally, claiming a mistake of law is not a valid defense in criminal cases. The legal principle is that everyone is presumed to know the law, and ignorance of the law is typically not an excuse for breaking it. However, there is a very narrow exception: a mistake of law might be a defense if an individual genuinely relied on an official, authoritative statement of the law that later turned out to be incorrect. This could include a misstatement found in a statute, a ruling from a court, or an official interpretation provided by a government executive officer responsible for enforcing that law.

• Example 1 (General Rule - Not a Defense): A driver moves to a new state and assumes that the rules for turning right on a red light are the same as in their previous state, where it was always permitted unless explicitly prohibited by a sign. Unaware of the new state's law that prohibits right turns on red at all intersections unless a sign specifically allows it, the driver makes such a turn and receives a traffic citation. The driver's claim that they "didn't know the law changed" would be a mistake of law. They understood the factual situation (making a right turn at a red light) but misunderstood its legal effect. This mistake would generally not serve as a valid defense against the traffic ticket.

• Example 2 (Exception - Reliance on Official Statement): A small business owner wants to understand new regulations regarding the labeling of their products. They contact the official state consumer protection agency and receive a written response from a high-ranking official, explicitly stating that a particular ingredient does not need to be listed on the label. Relying on this official guidance, the owner produces and sells products with the simplified label. Later, an audit reveals the official's statement was incorrect, and the ingredient *is* legally required to be listed. The business owner's actions were based on a mistake of law, but their genuine reliance on direct, official, and authoritative guidance from the agency responsible for enforcing the labeling laws could potentially serve as a defense against penalties for mislabeling.

• Example 3 (Exception - Reliance on Judicial Opinion): A company operates a facility that generates a specific type of industrial byproduct. A recent, officially published judicial opinion from the highest court in the state interprets a particular clause of an environmental statute, ruling that this specific byproduct is *not* considered hazardous waste under the law. The company, relying on this binding judicial precedent, adjusts its waste disposal procedures to treat the byproduct as non-hazardous. Months later, the same court issues a new ruling, overturning its previous interpretation and clarifying that the byproduct *is* indeed hazardous. Here, the company made a mistake of law regarding the hazardous nature of their byproduct. However, their actions were based on a previously authoritative and officially published judicial opinion. Their reliance on this now-overturned but once-binding legal interpretation could be a defense against charges for improper disposal during the period when the initial ruling was in effect.