Heien v. North Carolina, 574 U.S. 54 (2014), was a decision by the United States Supreme Court, ruling that a police officer's reasonable mistake of law can provide the individualized suspicion required by the Fourth Amendment to the United States Constitution to justify a traffic stop.

[1]: 2 While watching for "criminal indicators of drivers [and] passengers", Sergeant Matt Darisse observed Vasquez drive by and thought he appeared "nervous".

[1]: 4  Heien then pleaded guilty to two counts of trafficking, while reserving his right to appeal the denial of his motion to suppress.

After careful analysis of the North Carolina statute governing brake lights, the Court of Appeals concluded that it required only one working "stop lamp".

The majority held that a police officer's reasonable mistake of law can indeed provide the individualized suspicion required by the Fourth Amendment to justify a traffic stop based upon that understanding.

In her concurring opinion, Kagan wrote that the full text of North Carolina's law "poses a quite difficult question of interpretation, and Sergeant Darisse's judgment, although overturned, had much to recommend it".

In her dissent, Sotomayor argued that the reasonableness of a search or seizure should instead be determined by evaluating "an officer's understanding of the facts against the actual state of the law.