Is voluntariness of consent to search or seize a question of fact, law or both?

Back in 2013, I wrote a post about whether the voluntariness of consent to search or seize under the Fourth Amendment should be treated as a matter of fact or a question of law for purposes of the standard of review on appeal. From the post:

[I]t's a little weird to think of voluntariness as just a fact. Whether consent is voluntary is a conclusion based on a legal sense of what voluntariness means. It must have at least some legal elements in it. So that raised the question, is voluntariness really just reviewed for clear error as a fact, or is it a mixed judgment of law and fact, with the "what happened" part reviewed for clear error and the "so does that amount to consent" part reviewed de novo?

As I noted in my 2013 post, courts seemed unsure of the correct standard. I continued:

[M]aybe this is an issue for the Supreme Court to clarify. The Court's decision in Schneckloth v. Bustamonte leaves the precise nature of voluntariness inquiries somewhat murky, and that has led to considerable uncertainty in the federal court of appeals. I looked quickly through the caselaw of the Seventh Circuit, for example, and I also found Seventh Circuit cases taking both sides of the law/fact issue. Compare United States v. Jones, 614 F.3d 423, 435 (7th Cir. 2010) ("We will reverse a district court's finding of voluntary consent only if it is clearly erroneous.") with United States v. Wade, 400 F.3d 1019 (7th Cir. 2005) ("Questions of law-that is, the legal conclusion of whether Wade's consent was voluntary and whether he was illegally seized-are reviewed de novo.") So it may be a source of widespread confusion in the circuit courts generally, and therefore is an issue that the Supreme Court would be best situated to clarify.

In light of that post, I thought I would flag a very interesting cert petition from the Jenner & Block Supreme Court Clinic at the University of Chicago in Aksu v. California. Here's the Question Presented:

The federal courts of appeals and state courts of last resort acknowledge that they are intractably split about a recurring and important issue under the Fourth Amendment. A large number of courts treat the question of whether a defendant voluntarily consented to a warrantless search as a mixed question of fact and law that is reviewed de novo on appeal, much like the voluntariness of a confession under the Fifth Amendment. An equally large number of courts, including the court here, have treated the voluntariness of a consent to a search as a factual question, subject only to highly deferential appellate review.

The question presented is: What is the standard by which appellate courts review a trial court's holding that a defendant voluntarily consented to a warrantless search for Fourth Amendment purposes?

California waived its right to file a response, but the court directed California to file one anyway. California has now filed its Brief in Opposition, the Argument section of which begins:

Aksu asks this Court to resolve a conflict in authority concerning "the standard by which appellate courts review a trial court's holding that a defendant voluntarily consented to a warrantless search for Fourth Amendment purposes." Pet. i. To the extent state and federal appellate courts have applied differing standards of review to that question, few have done so on the basis of considered analysis despite the apparent longevity of the conflict. That the issue has not attracted the particular attention of appellate courts is perhaps attributable to the fact that, as this case illustrates, the standard of review will seldom, if ever, control the outcome of the question. Therefore, the conflict does not appear to be a very significant one.

As always, stay tuned.