Ignorance of the law is no defense. You may have heard of this legal maxim, which is meant to convey that, in most instances, doing something illegal is—well, illegal—even if you didn’t know it was illegal. In essence, you’re credited with knowing the law, whether or not you do.
But what about the other side of the coin? What if an officer believes some act violates the law when it really doesn’t, and detains you due to that mistaken belief?
Obviously, the government can’t convict you of the crime that’s the basis of the detention—because it isn’t really a crime. The more tricky question is whether the detention (“seizure”) is itself illegal. It’s a particularly important question where the seizure gives way to a search that turns up incriminating evidence.
The United States Supreme Court, through Chief Justice John Roberts, laid down the relevant Fourth Amendment law on Monday, December 15. Voting 8-1, it held that an officer’s reasonable mistake of law can provide the reasonable suspicion that’s necessary for a detention. (Heien v. North Carolina, 574 U. S. ____ (2014).)
On an April morning in 2009, a Sherriff’s Sergeant in Dobson, North Carolina, sat, waiting in his patrol car. As he watched the cars on Interstate 77 pass by, he came to focus on one. The driver of the Ford Escort in question struck Sergeant Matt Darisse as “very stiff and nervous.” Sergeant Darisse hopped onto the interstate and followed the Escort. Shortly thereafter, Darisse saw the Escort brake. Only the left brake light worked. He pulled the car over.
A man named Vasquez had been the driver. When Sergeant Darisse approached the car and looked in, a fellow named Heien was lying across the back seat. The Sergeant ran Vazquez’s license and registration; nothing of note came up. He gave Vazquez a warning ticket for the faulty brake light, but had grown increasingly suspicious during the encounter. Darisse experienced Vazquez as nervous, and he thought it strange that Heien never sat up. Darisse apparently asked the two men where they were going; he would later call their replies inconsistent.
Darisse continued to ask questions. He asked for and received Vasquez’s consent to a search of the car. Vazquez identified Heien as the owner, and Heien consented, too.
Darisse and a responding officer then hunted for evidence. They eventually found cocaine in the side compartment of a duffle bag.
State prosecutors charged Heien with attempted cocaine trafficking. Heien moved to suppress the evidence gathered by the officers on the grounds that the stop was illegal. (An illegal stop usually means an ensuing search is unlawful, too.)
A North Carolina appeals court sided with Heien. It determined that driving with only one functioning brake light wasn’t illegal in North Carolina. The vehicle code statute in question referred to “stop lamp” in the singular. So, the court reasoned, a driver needs only one working brake light. Because the officer’s misinterpretation of the law was the only basis for the stop, the detention and the search were illegal.
The North Carolina Supreme Court then weighed in. It disagreed with the appeals court, holding that the officer could have reasonably—even if wrongly—read the vehicle code to require two working brake lights. Because the mistake of law was reasonable, the state high court held, the stop and search were, too.
Officers need probable cause to make a warrantless arrest. But they need only reasonable suspicion of criminal behavior to detain someone. The idea is that the officer observes some set of circumstances that is objectively suspicious. In the area of traffic stops, reasonable suspicion often consists of an officer noticing a driver doing something illegal—for instance, speeding. The officer sees the driver travelling too fast; he has reasonable suspicion and may therefore stop the vehicle.
Courts have long held that detentions are valid even where the detaining officer is reasonably mistaken about the facts at hand. Suppose an officer reasonably misjudges the length of a crack in the windshield of a car on the road. She knows that cracks of a certain length are illegal; motorists must fix them before driving. She stops the driver with the fissure. After stopping the driver—or perhaps when the case gets to court—she learns that the crack fell just short of the illegal length. If the officer had issued a ticket for the crack, it would be invalid. But most courts would hold that the stop was lawful as based on a reasonable “mistake of fact.” Any evidence the officer were to have discovered as a result of the stop would likely be admissible in court. (See Traffic Stops Based on Officer Mistakes.)
At least until Monday, courts seemed to differentiate between mistakes of fact (the crack’s length) and mistakes of law (whether drivers need two operational brake lights). Even if an officer’s misunderstanding of the law is reasonable, these courts would say, it cannot serve as a legitimate basis for a detention.
The End—or Not
In the Heien case, the Supreme Court considered the officer’s confusion around North Carolina braking-light law reasonable. In essence, the Court found that references to “rear lamps” in the state vehicle code made understandable Sergeant Darisse’s belief that drivers need two working brake lights. The Court noted that North Carolina courts hadn’t previously construed the “stop lamp” section, meaning that Darisse didn’t have any notice that his reading of the law was wrong.
Critics of the decision contend that the Court has just encouraged officers to remain willfully blind of the law. To them, the Supremes are saying, “Don’t bother reading up on that law there, lest you should realize it doesn’t allow you to detain someone when you think it does.” Chief Justice Roberts tried to swat that argument away, emphasizing that “[t]he Fourth Amendment tolerates only reasonable mistakes, and those mistakes—whether of fact or of law—must be objectively reasonable.”
The bottom line: Because Sergeant Darisse’s mistake about the law was reasonable, the stop was constitutional. The effect: the cocaine was legally admissible. Police officers throughout the country rejoice (or at least grin).
But the story may not be completely over. The U.S. Supreme Court’s opinion is the law of the land—when it comes to the federal constitution. The Heien decision deals with the Fourth Amendment to the U.S. Constitution. States, though, have their own constitutions, and they’re free to expand individual liberties with them. So, interpreting its own constitution to invalidate mistake-of-law-induced detentions, a state court could plausibly thumb its nose at SCOTUS.