RALEIGH – The American Civil Liberties Union and other groups have filed a friend-of-the-court brief in a North Carolina case the U.S. Supreme Court will hear this fall that asks whether a traffic stop based on a police officer’s mistaken understanding of traffic laws violates the Fourth Amendment’s prohibition on unreasonable searches and seizures.

The ACLU's amicus brief, submitted with ACLU of North Carolina, the National Association of Criminal Defense Lawyers and the Cato Institute, argues that a mistake of law can never supply the reasonable suspicion of wrongdoing that the Fourth Amendment requires in order to justify a traffic stop.

“Ignorance of the law is not an excuse for motorists, and it shouldn’t be an excuse for the police, either,” said ACLU-NC Legal Director Chris Brook.

The vehicle owner in this case, Nicholas Heien, was stopped by the police because his car had only one working tail light, which the police officer mistakenly believed was a violation of North Carolina law. (One working tail light is legal in North Carolina.) After conducting a search, police subsequently found cocaine and charged Heien with drug trafficking. The North Carolina Appeals Court overturned the decision, finding that the mistaken stop violated Heien’s Fourth Amendment rights. The North Carolina Supreme Court later reversed that ruling, 4-3, prompting an appeal to the U.S. Supreme Court.

Read the ACLU brief in Heien v. North Carolina here.