## Facts

- Sergeant Matt Darisse of the Surry County Sheriff’s Department followed a Ford Escort on I-77 near Dobson, North Carolina, after observing the driver seemed stiff and nervous.
- The driver, Maynor Javier Vasquez, had Nicholas Heien (the vehicle’s owner) lying across the back seat.
- Darisse saw the Escort brake and observed that only the left brake light illuminated; the right brake light did not.
- Believing North Carolina law required two functioning brake lights, Darisse stopped the vehicle and said he would likely issue only a warning if documents checked out.
- During the stop, Darisse became suspicious based on the occupants’ behavior and inconsistent statements about travel plans.
- After issuing a warning, Darisse asked additional questions and requested consent to search; Vasquez deferred to Heien, who indicated he did not care.
- The search revealed approximately 54.2 grams of cocaine, and Heien was arrested and charged with attempted trafficking in cocaine.
- Heien moved to suppress, arguing the stop lacked lawful basis because state law required only one working brake light; the trial court denied suppression, Heien pleaded guilty while reserving appeal rights, and the North Carolina Supreme Court ultimately upheld the stop.
- The U.S. Supreme Court granted review to decide whether a reasonable mistake of law can supply reasonable suspicion under the Fourth Amendment.

## Issues

1. Whether a police officer’s objectively reasonable mistake of law can provide the reasonable suspicion required by the Fourth Amendment to justify a traffic stop.

## Decision

- The Supreme Court affirmed the judgment upholding the stop, in an 8–1 decision.
- The Court held that a seizure can be reasonable under the Fourth Amendment when based on an officer’s objectively reasonable mistake of law, as well as a reasonable mistake of fact.
- The Court concluded the officer’s interpretation of the brake-light statute, though incorrect, was objectively reasonable given the statute’s ambiguity and lack of prior authoritative construction.

## Legal Principles

- The Fourth Amendment permits searches and seizures based on objectively reasonable mistakes, including certain mistakes of law.
- The mistake must be objectively reasonable; the rule does not excuse ignorance of clear law or careless legal misunderstanding.
- Reasonable suspicion depends on an officer’s reasonable understanding of both facts and law.
- Statutory ambiguity and the absence of prior judicial interpretation may support a finding that an officer’s legal mistake was objectively reasonable.

## Conclusion

A traffic stop does not violate the Fourth Amendment when the officer’s basis for the stop rests on an objectively reasonable, though mistaken, interpretation of an ambiguous law; in such circumstances, the mistake of law can supply reasonable suspicion.


Heien v. North Carolina, 574 U.S. 54 (2014)