By Lisa Soronen

In the Heien v. North Carolina case, a police officer pulled over a car because he thought North Carolina law required motor vehicles have two working brake lights. It turns out the officer was wrong. The North Carolina Court of Appeals concluded that state law requires motor vehicles to only have one working brake light.

So how did the court come to that novel conclusion? The relevant statutes—which were more than a half a century old—referred “a” and “the” “stop lamp,” all singular.

When the driver and the passenger offered different stories about where they were going, the officer asked to search the vehicle. Consent was given and cocaine was found.   

The U.S. Supreme Court will decide whether a traffic stop is permissible under the Fourth Amendment when it is based on an officer’s misunderstanding of the law. The North Carolina Supreme Court ruled that reasonableness is the “primary command” of the Fourth Amendment, “[a]ccordingly, requiring an officer to be more than reasonable, mandating that he be perfect, would impose a greater burden than that required under the Fourth Amendment.” 

The court also pointed out that reasonable suspicion does not require an officer to actually view a violation of the law before making a stop. And the court did not want to discourage police officers from stopping cars where they believe the law has been violated. 

Three judges dissented, criticizing the majority’s reasoning and pointing out that “[b]y adopting the majority's rule, we are not only potentially excusing mistakes of law in the exceedingly rare case when the Court of Appeals divines a novel interpretation of a statute, but also those mistakes of law that arise from simple misreadings of statutes, improper trainings, or ignorance of recent legislative changes.” 

Police officers misunderstanding traffic laws appears to be common. In an Eleventh Circuit case (United States v. Chanthasouxat), an officer was trained to believe an inside rear-view mirror was required and wrote more than 100 tickets for a lack of such a mirror. But it turns out it wasn’t. 

Police would obviously benefit from being given the benefit of the doubt regarding understanding and interpreting traffic laws. If the court reverses the North Carolina Supreme Court (and even if it doesn’t), state legislatures might consider revising outdated traffic laws so that misunderstandings of law are less common.

Lisa Soronen is executive director of the State and Local Legal Center. She writes frequently on U.S. Supreme Court cases for the NCSL Blog. email Lisa.

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