In Heien v. North Carolina a police officer pulled over a car because he thought that North Carolina law required that motor vehicles have two working brake lights.  It turns out the officer was wrong.  The North Carolina Court of Appeals, interpreting a statute over a half a century old, concluded that state law requires motor vehicles to only have one working brake light.  The statute referred “a” and “the” “stop lamp,” all singular. 

When the driver and the passenger offered different stories as to where they were going, the officer asked to search the vehicle.  Consent was granted 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 reasoned 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 above 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 that a city ordinance required inside rear-view mirror and wrote more than 100 tickets for a lack of such a mirror.  But it turns out it wasn’t. 

Local 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Court reverses the North Carolina Supreme Court (and even if it doesn’t), cities and counties should consider revising outdated traffic laws so that misunderstandings of law are less common.