Supreme Court Says Ignorance Of The Law Is An Excuse — If You’re A Cop


There is one simple concept that law students learn in their very first weeks of criminal law class: Ignorance of the law is no excuse. This principle means that when an individual violates the law, it doesn’t matter whether or not they knew what the law said. If it’s a crime, and they are found to have committed the elements of that crime, they are guilty.

On Monday, the U.S. Supreme Court ruled that the same standard doesn’t necessarily apply to police. In a splintered 8–1 ruling, the court found that cops who pulled over Nicholas Heien for a broken taillight were justified in a subsequent search of Heien’s car, even though North Carolina law says that having just one broken taillight is not a violation of the law.

The ruling means that police did not violate Heien’s rights when they later searched his car and found cocaine, and that the cocaine evidence can’t be suppressed at a later trial. But it also means that the U.S. Supreme Court declined the opportunity to draw a line limiting the scope of police stops, at a time when they are as rampant and racially disproportionate as ever. Instead, police may have considerably more leeway to stop passengers on the road, even in a number of jurisdictions that had previously said cops are not justified in mistakes of law.

The case hinged on a question of “reasonableness.” North Carolina’s law requires that a driver have one working rear taillight, not two. But the law also has some other language that suggests “other” lamps be in “working order.” If there was any ambiguity about this statute, the North Carolina Supreme Court has cleared it up, holding that the “other” lamps language does not refer to tail lights.


Nonetheless, because the statute is confusing, the state argued that the cops had made a “reasonable” mistake when they pulled over Heien for having one tail light, and thus were not precluded from using the evidence that came out of that stop. This assertion is controversial in and of itself. After all, police already have such vast leeway to make traffic stops that Fourth Amendment scholar Orin Kerr recently quipped, “if an officer can’t find a traffic violation to stop a car, he isn’t trying very hard.” Now police have to try even less hard.

If it were up to the two concurring justices, Ruth Bader Ginsburg and Elena Kagan, the ruling would have stopped here. It would have held that the stop of Heien was “reasonable” even though the officers made a mistake, because the law itself was particularly unclear.

The vague language of the majority holding, however, seemingly went much further. Writing for the majority, Chief Justice John Roberts held that “investigatory stops” — when police stop someone on the street or in a car and may subsequently question, frisk, or search them — are simply not held to the same standard as criminal convictions.

He dismissed the refrain “ignorance of the law is no excuse” as a maxim with “rhetorical appeal,” but not worthy of the court’s serious consideration, at least not when it comes to investigatory stops. “[J]ust 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,” he writes.

Justice Sonia Sotomayor, who is a former prosecutor, has significant concerns with the scope of this holding.

“One wonders how a citizen seeking to be law-abiding and to structure his or her behavior to avoid these invasive, frightening, and humiliating encounters could do so,” she wrote. She also noted the “human consequences,” “including those for communities and for their relationships with the police” of broader leeway for police stops, seemingly making reference to current outrage over police brutality and community mistrust.


She doesn’t think it makes any sense to apply a lesser standard to stops than to convictions. And she doesn’t like the vague, permissive standard that will likely result in “murky” application of the law.

Perhaps most importantly, Sotomayor points out that the cost of prohibiting stops when officers actually make a mistake of the law would be very small, compared to a potentially great consequences of allowing them to do so. After all, when cops mistakenly pull someone over in a circumstance like that in this case, they suffer no consequence. The only result is that the evidence they collect cannot be used in a later prosecution. When cops mistakenly pull over citizens, a subsequent drug prosecution is one of just a number of adverse consequences that can follow.