Affirming State v. Heien, 366 N.C. 271 (Dec. 14, 2012), the Court held that because an officer’s mistake of law was reasonable, it could support a vehicle stop. In Heien, an officer stopped a vehicle because one of its two brake lights was out, but a court later determined that a single working brake light was all the law required. The case presented the question whether such a mistake of law can give rise to the reasonable suspicion necessary to uphold the seizure under the Fourth Amendment. The Court answered the question in the affirmative. It explained:

[W]e have repeatedly affirmed, “the ultimate touchstone of the Fourth Amendment is ‘reasonableness.’” 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.” We have recognized that searches and seizures based on mistakes of fact can be reasonable. The warrantless search of a home, for instance, is reasonable if undertaken with the consent of a resident, and remains lawful when officers obtain the consent of someone who reasonably appears to be but is not in fact a resident. By the same token, if officers with probable cause to arrest a suspect mistakenly arrest an individual matching the suspect’s description, neither the seizure nor an accompanying search of the arrestee would be unlawful. The limit is that “the mistakes must be those of reasonable men.”

But reasonable men make mistakes of law, too, and such mistakes are no less compatible with the concept of reasonable suspicion. 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. Whether the facts turn out to be not what was thought, or the law turns out to be not what was thought, the result is the same: the facts are outside the scope of the law. There is no reason, under the text of the Fourth Amendment or our precedents, why this same result should be acceptable when reached by way of a reasonable mistake of fact, but not when reached by way of a similarly reasonable mistake of law.

Slip op. at 5-6 (citations omitted). The Court went on to find that the officer’s mistake of law was objectively reasonable, given the state statutes at issue:

Although the North Carolina statute at issue refers to “a stop lamp,” suggesting the need for only a single working brake light, it also provides that “[t]he stop lamp may be incorporated into a unit with one or more other rear lamps.” N. C. Gen. Stat. Ann. §20–129(g) (emphasis added). The use of “other” suggests to the everyday reader of English that a “stop lamp” is a type of “rear lamp.” And another subsection of the same provision requires that vehicles “have all originally equipped rear lamps or the equivalent in good working order,” §20–129(d), arguably indicating that if a vehicle has multiple “stop lamp[s],” all must be functional.

Slip op. at 12-13.