Ignorance of the Law is No Excuse…..Unless You’re a Cop

There is a famous maxim “ignorantia juris non excusat,” Latin for “ignorance of the law does not excuse.”  Merely being unaware that something is against the law is normally not a way to escape being convicted of a crime.

However, the Supreme Court just held in Heien v. North Carolina that a police officer can justify a stop under the Fourth Amendment based on a mistake of law, so long as the mistake was made reasonably.