In Heien v. North Carolina, the Supreme Court held that where a police officer makes a stop based upon a reasonable mistake about a law, the stop is justified.
In this case, an officer stopped a vehicle because one of its two brake lights was out, based on a misunderstanding that the North Carolina law permitted only one working brake light. The officer stopped Heinen’s vehicle because one light was not working and then proceeded to a consensual search of the car. The search turned up a bag of cocaine located in a duffle bag in the trunk. Heinz was arrested and convicted of attempted drug trafficking. The question presented to the Court was whether a police officer’s reasonable mistake of law can give rise to the reasonable suspicion necessary to uphold a seizure of an automobile and the occupants in it under the Fourth Amendment.
The North Carolina statute reads that a car must be:
equipped with a stop lamp on the rear of the vehicle. The stop lamp shall display a red or amber light visible from a distance of not less than 100 feet to the rear in normal sunlight, and shall be actuated upon application of the service (foot) brake. The stop lamp may be incorporated into a unit with one or more other rear lamps. N. C. Gen. Stat. Ann. §20–129(g) (2007).
The Court concluded that the statute required only one stop lamp to be working. However, the officer was under a different impression of the law at the time. A nearby statute requires that “all originally equipped rear lamps” be functional. N. C. Gen. Stat. Ann. §20–129(d). The officer made the stop under a mistake in law. Nevertheless, the Court held that even if an officer reasonably misunderstood the law, as long as the officer conducts a search or seizure reasonably under the Fourth Amendment he is acting justifiably.
“To be reasonable is not to be perfect, and so the Fourth Amendment allows for some mistakes on the part of government officials, giving them ‘fair leeway for enforcing the law in the community’s protection.'” Reasonable mistakes of fact are permissible. For example, when someone consents to the search of a home, the search will be considered valid even if the officer mistakenly believes that the person consenting is the owner.
Reasonable mistakes of law are also permissible. “Reasonable suspicion arises from the combination of an officer’s understanding of the facts and his understanding of the relevant law. The officer may be reasonably mistaken on either ground.” Even laws that police enforce that are later declared unconstitutional by a court does not rebut an officer’s reasonable assumption that the laws were valid at the time.
Heinen argued that there is no margin of error for an officer’s mistake of law. He argued the legal maxim: “Ignorance of the law is no excuse.” If persons cannot get out of trouble by claiming they were mistaken about the law, then neither can the police.
But the Court concluded the law protects against only “reasonable mistakes,” and therefore, “an officer can gain no Fourth Amendment advantage through a sloppy study of the laws he is duty-bound to enforce.” The Court further concluded Heinen’s reliance on the legal maxim is misplaced. A person cannot escape criminal liability by claiming he did not know the law, but neither can the government impose criminal liability by a mistaken understanding of the law. The Court explained:
If the law required two working brake lights, Heien could not escape a ticket by claiming he reasonably thought he needed only one; if the law required only one, Sergeant Darisse could not issue a valid ticket by claiming he reasonably thought drivers needed two. But just because mistakes of law cannot justify either the imposition or the avoidance of criminal liability, it does not follow that they cannot justify an investigatory stop.
In this case, Heien did not appeal his brake-light ticket. Instead, he appealed a cocaine-trafficking conviction, as to which he did not claim the police made either a mistake of fact or law.