December 15, 2014, was not a proud day for the United States Supreme Court, when it decided 8-1 that a traffic stop is not invalidated when based on a police officer’s reasonably mistaken reading of the law.

Nicholas Heien was driving with a broken brake light. That was the sole basis that police officer Matt Darisse used to stop him, subsequently finding cocaine through a purported consent search, and charging Mr. Heien with attempted drug trafficking. Heien v. North Carolina, ___ U.S.___ (Dec. 15, 2014). This was a pretextual stop, meaning that officer Darisse followed Mr. Heien apparently wanting to find a reason to stop him, to investigate after seeing him looking nervous after passing officer Darisse. Most people commit moving violations; a police officer needs only to follow a suspect driver long enough to observe moving violations or to wait for the driver to reach the driver’s destination or to run out of gas. I surmise plenty of police will even try to lead a suspect to commit a moving violation, including by tailgating a suspect, thus leading plenty of suspects to speed up or swerve not only to avoid the dangerous tailgating situation, but also as a reaction to the tailgater being a cop, who should be obeying the traffic laws, rather than breaking tailgating laws.

Congratulations to Mr. Heien’s lawyer for having read the North Carolina law to have seen that the state law only requires one working break light. That one-light requirement, even if counterintuitive or a legislative drafting error (thus requiring the legislature, not the courts, to address rewriting the statute), is as plain as day in a short statutory statement, easily available at all times to officer Darisse, who as highly ranked as he is — a sergeant — not only has no excuse not to know this law, but also a duty to assure that his subordinates know such a basic law.

Sadly, eight of nine Supreme Court justices easily decided that officer Darisse’s stop of Mr. Heien was Constitutional, and not a Fourth Amendment search and seizure violation. The Court likened officer Darisse’s claimed mistaken legal interpretation to an officer who stops an apparently sole driver for a high occupancy vehicle lane violation, only to find two small children in the car, too short to have been seen before stopping the car.

Praised be lone dissenter Justice Sotomayor, for having pointed out that a police officer has a unique vantage point in observing such a factual scenario as whether only one person occupies a car in an HOV lane, but that courts have the same vantage point as a police officer in reading the applicable law.

Heien’s language applies beyond mere traffic stops, to all instances where police say "Oops! I mistakenly interpreted the law" when a Fourth Amendment challenge is raised. As Justice Sotomayor says in her dissent in Heien, the case marks an erosion of the public’s Fourth Amendment rights. Heien will dissuade police from knowing the applicable law and assuring that police are trained on the law; then when they make a mistake in applying the law, they will simply claim a Heien reasonable mistake of the law.