The Supreme Court has handed down Heien v. North Carolina, the Fourth Amendment case I have blogged about a few times on whether the Fourth Amendment is violated when an officer pulls over a car based on a reasonable but mistaken belief that the traffic laws prohibit the drivers conduct. The Court ruled 8-1, per Chief Justice Roberts, that the Fourth Amendment is not violated in such circumstances. Only Justice Sotomayor dissented. The basic reasoning of the case is simple, but it leaves some complications that have some interesting implications for lower courts and for the relationship between Fourth Amendment rights and remedies.

Heres the core of the Chief Justices opinion:

As the text indicates and we have repeatedly affirmed, the ultimate touchstone of the Fourth Amendment is reasonableness. Riley v. California, 573 U. S. ___, ___ (2014) (slip op., at 5) (some internal quotation marks omitted). To be reasonable is not to be perfect, and so the Fourth Amendment allows for some mistakes on the part of government officials, giving them fair leeway for enforcing the law in the communitys protection. Brinegar v. United States, 338 U. S. 160, 176 (1949). . . .

Reasonable suspicion arises from the combination of an officers understanding of the facts and his understanding of the relevant law. The officer may be reasonably mistaken on either ground. Whether the facts turn out to be not what was thought, or the law turns out to be not what was thought, the result is the same: the facts are outside the scope of the law. There is no reason, under the text of the Fourth Amendment or our precedents, why this same result should be acceptable when reached by way of a reasonable mistake of fact, but not when reached by way of a similarly reasonable mistake of law.

The Courts holding raises two major questions. First, how much law does a reasonable police officer know? And second, if a reasonable mistake of law means there was no Fourth Amendment violation, how do we reconcile that with the remedies cases saying that a reasonable mistake of law is a reason why there is no Fourth Amendment remedy? Ill consider each in turn.

(1) How much law does a reasonable police officer know?

If the Fourth Amendment incorporates reasonable mistakes of law, then there must be a standard for how much law a reasonable officer knows. For example, does a reasonable officer just follow the text of the law like a lawyer would? Does he know the major cases interpreting the law? Or does he just know what is taught at the police academy, or maybe what the public thinks the law probably is?

The majority opinion says that the standard is whether it is objectively reasonable for an officer in [the searching officer's] position to think that the conduct violated the law. The opinion explains:

[T]he inquiry is not as forgiving as the one employed in the distinct context of deciding whether an officer is entitled to qualified immunity for a constitutional or statutory violation. Thus, an officer can gain no Fourth Amendment advantage through a sloppy study of the laws he is duty-bound to enforce.

Thats a start, although its still pretty vague. Sloppiness is a relative term. A sloppy study of the law for a lawyer might be a very careful study of the law for a non-lawyer. Whats the reference point to determine sloppiness? The Courts application of the standard at the end of the opinion mostly focuses on the text of the law, and also notes the absence of cases construing the text. So maybe the reasonable officer knows the text and is aware of at least major cases interpreting it? Its hard to say.

Link:

Volokh Conspiracy: Reasonable mistake of law can generate reasonable suspicion, Supreme Court holds