Yes. The stop was legal because the Constitution only protects people from *unreasonable* police actions, not perfect ones. The brake light law was confusing, and the officer made an honest and reasonable mistake. Just as police are allowed to make reasonable mistakes about facts (like thinking a suspect dropped a weapon when it was just a phone), they are also allowed to make reasonable mistakes about confusing laws. Since the officer's mistake was reasonable, the traffic stop was not an unreasonable seizure.

No. The stop was illegal because 'ignorance of the law is no excuse,' and that should apply to police officers, too. Police should be judged based on what the law actually is, not what they think it is. Allowing officers to stop people for things that aren't illegal gives them too much power, makes it hard for people to know how to follow the rules, and lets confusing laws stay on the books without being clarified. If no law was broken, the stop should not have happened.

Yes, the stop was okay. Police officers can make reasonable mistakes about the law and still have a good reason to stop someone. They don't have to be perfect, just reasonable. The law about brake lights was confusing, so the officer's mistake was reasonable.

I agree with the majority. But the test for a reasonable mistake of law is harder than the test for qualified immunity. The law has to be really confusing for the officer's mistake to be reasonable. Here, the brake light law was confusing enough that the officer's mistake was reasonable.

I disagree. If a police officer is wrong about the law, that shouldn't give them a reason to stop someone, even if the mistake was reasonable. It's not fair to people and it makes it harder for people to know how to follow the law. We should say that a mistake about the law is never a good reason for a stop.

Yes, the stop was okay. We hold that police officers can make reasonable mistakes about the law and still have a good reason to stop someone. Officers don't have to be perfect, just reasonable. The law about brake lights was confusing, so the officer's mistake was reasonable.

I concur. But the test for a reasonable mistake of law is harder than the test for qualified immunity. The law has to be really confusing for the officer's mistake to be reasonable. Here, the brake light law was confusing enough that the officer's mistake was reasonable.

I respectfully dissent. If a police officer is wrong about the law, that shouldn't give them a reason to stop someone, even if the mistake was reasonable. It's not fair to people and it makes it harder for people to know how to follow the law. A mistake about the law is never a good reason for a stop.

Yes. A police officer's reasonable mistake of law can give rise to the reasonable suspicion required for a seizure under the Fourth Amendment. The 'ultimate touchstone' of the Fourth Amendment is reasonableness, not perfection. The Court has long held that the Fourth Amendment allows for reasonable mistakes of fact, and there is no reason to treat reasonable mistakes of law differently. Reasonable suspicion is formed by an officer's understanding of both the facts and the law, and a reasonable mistake on either ground does not invalidate the seizure. Historical precedent, such as 19th-century customs seizure cases, shows that a 'doubt as to the true construction of the law' can be a reasonable cause for a seizure. In this case, the North Carolina brake light statute was ambiguous and had not been interpreted by the state's appellate courts, making Sergeant Darisse's belief that two working brake lights were required objectively reasonable. Therefore, the stop was lawful.

No. An officer's mistake of law, no matter how reasonable, cannot support the individualized suspicion necessary to justify a seizure under the Fourth Amendment. The reasonableness inquiry has always focused on an officer's assessment of facts against a fixed, objective legal standard. The law is definite and knowable, and it is the role of courts, not officers, to interpret it. Allowing seizures based on legal misinterpretations expands police authority, creates uncertainty for citizens trying to obey the law, and perversely discourages the clarification of ambiguous statutes. The majority's reliance on Michigan v. DeFillippo is misplaced, as that case involved an officer correctly enforcing a law that was presumptively valid at the time, not a non-existent offense as was the case here. This holding erodes Fourth Amendment protections and subjects innocent citizens to 'invasive, frightening, and humiliating' stops based on an officer's misunderstanding.

Yes. Because the officer's mistake about the brake-light law was reasonable, the stop in this case was lawful under the Fourth Amendment. The Fourth Amendment requires government officials to act reasonably, not perfectly, and gives those officials 'fair leeway for enforcing the law.' Searches and seizures based on mistakes of fact may be reasonable. The limiting factor is that 'the mistakes must be those of reasonable men.' Reasonable men make mistakes of law, too, and such mistakes are no less compatible with the concept of reasonable suspicion. The Fourth Amendment tolerates only objectively reasonable mistakes, regardless of the officer's subjective understanding.

I agree with the majority that a police officer's reasonable mistake of law can give rise to reasonable suspicion. However, the inquiry the Court allows is more demanding than the one for qualified immunity. The test is satisfied when the law at issue is 'so doubtful in construction' that a reasonable judge could agree with the officer's view. In this case, the North Carolina law is genuinely ambiguous, so the officer's judgment, though overturned, had much to recommend it and thus the stop was lawful.

A police officer's understanding of the law is not an input into the reasonableness inquiry of a search or seizure under the Fourth Amendment. Permitting mistakes of law to justify seizures has human consequences, including further eroding the Fourth Amendment's protection of civil liberties in a context where that protection has already been worn down. It also has the perverse effect of preventing or delaying the clarification of the law. The more administrable approach, and the one more consistent with our precedents and principles, would be to hold that an officer's mistake of law, no matter how reasonable, cannot support the individualized suspicion necessary to justify a seizure under the Fourth Amendment.

I agree with the majority that a police officer's reasonable mistake of law can give rise to reasonable suspicion. However, the inquiry we allow is more demanding than the one for qualified immunity. The test is satisfied when the law at issue is 'so doubtful in construction' that a reasonable judge could agree with the officer's view. In this case, the North Carolina law is genuinely ambiguous, so the officer's judgment, though overturned, had much to recommend it and thus the stop was lawful.

The police officer's understanding of the law is not an input into the reasonableness inquiry of a search or seizure under the Fourth Amendment. Permitting mistakes of law to justify seizures has human consequences, including further eroding the Fourth Amendment's protection of civil liberties in a context where that protection has already been worn down. It also has the perverse effect of preventing or delaying the clarification of the law. The more administrable approach, and the one more consistent with our precedents and principles, is to hold that an officer's mistake of law, no matter how reasonable, cannot support the individualized suspicion necessary to justify a seizure under the Fourth Amendment.

Heien v. North Carolina

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