Opinion analysis: Reasonable mistakes of law by police do not violate the Fourth Amendment

The exercise of police discretion to stop people on the street is front and center in todays headlines. In this case, a North Carolina policeman stopped Heiens car because it had a brake light that did not work. During the stop, Heien consented to a search of the car, which yielded cocaine in a duffle bag and Heiens ultimate conviction for attempted drug trafficking. On appeal, the North Carolina appellate courts surprisingly ruled that the outdated state vehicle code required only one working brake light (a stop lamp, in the words of the statute); therefore, there had been no violation of law that would permit the stop. The officer made no error about the facts; but he had been mistaken about the meaning of the law. However, the North Carolina Supreme Court ruled, the officers mistake about this law was reasonable, and for that reason the Fourth Amendment right to be secure from unreasonable seizures was not violated. This mornings opinion in Heien v. North Carolina affirms that holding.

The constitutional law of reasonableness
The vague word unreasonable in the Fourth Amendment is a lawyers playground, and questions about what sort of circumstances constitutionally permit law enforcement seizures have thus plagued the federal courts since the Fourth Amendment was adopted. In 1813, Chief Justice John Marshall wrote that the constitutional standard is circumstances which warrant suspicion a relatively unspecific and therefore unhelpful standard. But its unhelpfulness flows from the generality of the amendment itself. It is not judge-made policy; it is constitutional text.

Over the years the Court has honed its thinking about what constitutes probable cause to stop or search (for example, Illinois v. Gates in 1983), and in Terry v. Ohio in 1968 the Court famously ruled that even brief stops on the street require at least specific and articulable reasonable suspicion, not just hunches. The Court has subsequently made clear that even when police are mistaken about facts, their stops do not violate the Constitution if their mistakes are reasonable.

Todays opinion

Today, in an opinion by Chief Justice John Roberts, a majority of eight Justices affirmed that there is no reason why this same result should not apply when reached by way of a similarly reasonable mistake of law. The Court conceded and Justice Sonia Sotomayor, the lone dissenter, agreed that no precedent of the Court has expressly answered this reasonable mistake of law question (scarcely a peep). The Court noted, however, that as early as 1809, the Supreme Court ruled that a reasonable mistake of law about probable cause permitted a customs seizure under a federal statute. By 1860, this general principle had been adopted in numerous [lower court] cases. While acknowledging that the statutory customs cases were not directly on point for the constitutional question, the Court also explained that no decision of this Court in the two centuries since has undermined that understanding that reasonable mistakes of law can excuse governmental action. In fact, the Court explained that in more recent cases, such as Michigan v. DeFillippo, it had found no Fourth Amendment violation even when governmental searches were based on state statutes later declared unconstitutional. (Justice Sotomayor strongly disagreed with this reading.)

Arguing for Heien, attorney Jeffrey Fisher had struggle[d] to limit the Courts ruling solely [to] the exclusionary rule that is, the remedy in lieu of a more general ruling about the right (that is, whether the officers stop was an unreasonable violation of the amendment). This was likely an attempt to preserve some relief for Heien on remand, because North Carolina purportedly has not adopted a good faith exception to the exclusionary rule. But there will be no remand for further proceedings under todays ruling, which flatly affirmed the state courts ruling. The Court said that DeFillippo was plainly a decision about the meaning of probable cause, and thus its holding regarding a reasonable mistake of law cannot be transform[ed] into an exclusionary rule decision. So in this case, because the officers mistake about the meaning of North Carolinas vehicle code was reasonable, there was no violation of the Fourth Amendment in the first place.

(By contrast, the Court also noted that an individual officers mistaken view, no matter how reasonable, that he has complied with the Fourth Amendment, does not undermine a reviewing courts ultimate conclusion that governmental actions have violated the Fourth Amendment even though it might affect the remedy. This significant reservation regarding the scope of the Courts ruling is emphasized in footnote 1 of Justice Elena Kagans concurring opinion, and should not be overlooked.)

The majoritys limitations, and two separate opinions

Importantly, particularly in light of recent controversies, the Court observed that the standard of reasonableness for mistakes of law is not as forgiving as some might have it. An officers legal error must be objectively reasonable, and not based on a particular officers subjective understanding or on a sloppy study of the laws he is duty-bound to enforce. Thus, the Court suggested, an officer must learn[] the law, and I would expect that the familiar standard of a reasonably well-trained officer will be rigorously applied by lower courts when confronted with Heien errors in the future.

In a separate concurrence, while joining the majority opinion in full, Justice Kagan (joined by Justice Ruth Bader Ginsburg) emphasized these important limitations. Only a genuinely ambiguous statute should support a reasonable mistake about its meaning, one that would present judicial officers with interpretive work that is really difficult or very hard.

In a solo dissent, Justice Sotomayor argued, not unreasonably, that a fixed legal yardstick would be easier to administer than a floating standard of reasonable legal mistakes. The actual state of the law should control, rather than a reasonable misunderstanding about the law. Law enforcement would not be penalized if Fourth Amendment violations were found based on such legal misunderstandings, because good faith would prohibit the exclusion of evidence and qualified immunity would protect officers. Meanwhile, definite and clear interpretations of laws would be encouraged, rather than elided.

With only slightly veiled references to current controversies involving police confrontations on the street, Justice Sotomayor contended that the Courts less definite ruling would lead to further eroding [of] the Fourth Amendments protection of civil liberties where that protection has already been worn down. Police stops based on reasonable suspicion are invasive, frightening, and humiliating, and Justice Sotomayor submitted that todays ruling significantly expands this authority. There are human consequences including those for communities and for their relationships with the police. The majoritys rule, she continued, will prove murky in application and difficult for police and courts to administer. Of course, only time will tell whether todays reasonable mistake of law holding will be narrowly circumscribed, as both the concurrence and dissent insist it should be.

Ignorance of the law is still (usually) no excuse

Before closing, lets put one trending, but erroneous, sound bite to rest. Heien argued that because the common-law maxim ignorance of the law is no excuse applies to private citizens who break the law, it should also be applied to police here. Tweeters are now claiming that todays ruling means the maxim applies to everyone except the police. That not only ignores the very different contexts (criminal law breaking versus justifications for stopping suspected law-breakers), but its wrong also in its premise. In fact, the Court long ago ruled that a reasonable ignorance of the law can be a defense to prosecution. In Lambert v. California (1957), the Court vacated a criminal conviction because the law at issue could not be reasonably known to the citizenry. This ruling still finds application today, albeit rarely. It seems that the Court may have (even if not consciously) reinvigorated the Lambert concept today at page 12, where it indicated that the government cannot impose criminal liability based on a mistaken understanding of the law. If read broadly, this statement could represent a sea change in the modern understanding of Lambert a decision that Justice Frankfurter called, in dissent, a derelict on the waters of the law. But it seems clear that the Court today meant on [its own] misunderstanding of the law, not a private citizens.

Meanwhile, police who break the law are still subject to the usual maxim: ignorance of the law will not excuse their lawbreaking any more than anyone elses. But here, police are trying to implement the Fourth Amendment, not break the law. There is of course some tension between the idea that the law is definite and knowable versus an officers reasonable legal mistake. But the Court held today only that when police officers reasonably understand others to have broken the law, they may briefly stop them to investigate without violating the Fourth Amendment. Absent a shift in societal standards for law enforcement and recently we are witnessing at least a re-examination — this ruling seems unsurprising.

Final thoughts: Enforcing the Constitution is the hard part

Applying its holding to the facts today, the Court had little difficulty concluding that the police officers error of law was reasonable. The stop lamp provision of North Carolinas law had never been previously construed, and other parts of the code indicated that all rear lamps (plural) had to be functional. As Justice Kagan wrote separately, the officers belief here had much to recommend it. Indeed, it seems likely that virtually all drivers today believe, reasonably and objectively, that the law requires both their brake lights to work.

Todays headlines focus on questions of police discretion used to interact with people on the street. But it is the failure to enforce reasonable standards for police intervention that drives this concern, not the accepted legal rule that permits police intervention when there is reasonable suspicion. Factual mistakes seem inevitable within the constitutional standard of reasonableness — all that the Court ruled today is that reasonable men make mistakes of law too. The Framers intended reasonableness to be the key it is up to us to give meaningful enforcement to the term.