If a police officer gets the law wrong, are there any consequences for his mistake? Any of you familiar with qualified immunity will understand that generally the answer is “no.” Under qualified immunity, when a government official violates someone’s rights, the victim can only sue him for damages if the law demonstrating there was a rights violation was “clearly established.” And, as my colleagues have explained, it can be very difficult to establish the law is “clearly established.” Thus, if the law is at all unclear (and often even when it is pretty clear) the police officer can walk away and the victim receives nothing.

There’s a related question of where an officer can mistakenly get the law wrong, discover evidence in the process, and have that evidence used to prosecute someone even though the search or seizure leading to that evidence was in fact unlawful. That question was front-and-center at the New Jersey Supreme Court this week in State v. Carter, where it rejected a ruling of the U.S. Supreme Court under the Fourth Amendment when interpreting the equivalent provision in the New Jersey Constitution. It was an all-too-rare victory for accountability when the government violates the rights of the people.

The issue arose a few years ago at the U.S. Supreme Court in the case Heien v. North Carolina (2014). There, an officer pulled a car over because one—but only one—of his brake lights was out. The stop led to the discovery of drugs which the defendant was then prosecuted for. The defendant tried to have the evidence thrown out because what justified the original stop—having one brake light out—was actually fine under the relevant state statute. The officer simply thought the law required both brake lights but the state courts decided that the meaning of the statute is that actually you only need one.

Nevertheless, the U.S. Supreme Court ruled the evidence (and thus the defendant’s conviction) should not be suppressed. Why? Because the officer’s mistake of law was “reasonable.” The statute was a bit unclear and hadn’t been authoritatively interpreted before. Therefore, the Court stated, since the Fourth Amendment simply requires that warrantless searches and seizures (such as a roadside stop) be “reasonable,” that allows for a “reasonable” mistake of law. Since the stop was reasonable, the evidence could stay in.

The situation in New Jersey wasn’t conceptually that different. A statute makes it illegal to cover “marks” on a license plate with a license plate holder. The language is pretty clear that this doesn’t just concern the six or so letters and numerals that constitute the car’s unique license plate number. It also forbids the covering of other markings on the plate, including “New Jersey” and “Garden State.” So if your license plate holder covers up “Garden State” the police can pull you over and ticket you.

You might say, “That’s a really dumb law.” And you might be right. But New Jersey police officers apparently love the thing. The New Jersey Supreme Court found very relevant that the police issue over 100,000 tickets a year to drivers who violate the relevant statute. That statute covers a few other areas to do with license plates, but the lion’s share seems to be simply for having a license plate holder covering some of a plate’s extraneous markings.

Of course, the police don’t really care if other drivers can’t see on a particular car that New Jersey is, in fact, the “Garden State.” (Unless they’re unhealthily avid gardeners, I guess?) However, the law makes for a terrific excuse to pretextually stop drivers and conduct criminal investigations that otherwise would lack probable cause. And that’s exactly what happened to one of the defendants before the New Jersey Supreme Court, Miguel Roman-Rosado. A photo of his plate is above. The officer who pulled him over, and then found an unpermitted handgun, admitted that only around 10-15% of the words “Garden State” were obscured, and that the stop was a pretext (yes, he admitted that!).

So the first question before the court was did the law make obscuring some of the marks on a license plate illegal no matter how minor the obstruction, or only if the marks cannot reasonably be identified. Although the textual analysis of the statute was a tough question, which the court said both sides had reasonable arguments for, the court came down on the side of Mr. Roman-Rosado, essentially on grounds of common sense. It pointed out that masses of cars in any parking lot or on any highway have plate holders obscuring bits and pieces of letters on plates. This is true whether it’s the tops of the “N” and “J” in the state’s name, or random other letters either on the standard “Garden State” or words on the various specialty plates car owners can buy, from “Rotarian” to “Phillies.” Reading the statute to make all of those license plate holders illegal gives the police unfettered discretion to pretextually pull over a huge number of drivers. (Of course, allowing pretextual stops in the first place is the ultimate problem, but that’s another story.)

Thus, for Mr. Roman-Rosado at least, his stop turned out to be unlawful because you could still tell that his license plate said “Garden State.” (Another defendant on appeal, however, whose holder entirely blocked “Garden State,” wasn’t so lucky.) But that then led to the question of whether this reasonable mistake of law excused the officer’s conduct and meant the evidence of his unpermitted gun possession could be suppressed.

And on that issue the court broke with the U.S. Supreme Court. Recognizing something we’ve said at the Center for Judicial Engagement time and time again, state courts can interpret their state constitutions differently than the U.S. Constitution, even when the language of the two is identical. That’s the case here, where Article I, Paragraph 7 of the New Jersey Constitution is the same as the Fourth Amendment. The court disagreed with the U.S. Supreme Court’s interpretation in Heien, ruling that the relevant question is not whether the officer who reasonably misread the law is deterred if evidence is thrown out, as the U.S. Supreme Court did, but “whether a person’s rights have been violated.” It further explained that “it is not reasonable to restrict a person’s liberty or invade their privacy for behavior that no statute condemns” and that “[a]n officer’s reasonable but mistaken interpretation of a statute cannot change the fact that the law does not criminalize particular conduct.”

While I find the court to have come to the correct result, its analysis was rather short and could have used some more details. It did nothing like what the Iowa Supreme Court did earlier this summer, providing a deep historical look into the purpose and background of the state constitution’s Fourth Amendment equivalent. But its bottom line does send the important message that police officers’ ignorance of the law is no excuse. That’s one that hopefully those involved with qualified immunity will pay heed to.

Anthony Sanders is the director of IJ’s Center for Judicial Engagement.