We now have the Court’s resolution in Chatrie v. United States, and since I’ve written on what it ought to have said, and since it isn’t too far therefrom, this can be fairly brief.
TL;DR – Chatrie says, ‘We meant what we said in Carpenter: cellphone location information does not fall within the third party doctrine. And yeah, we can still only manage five Justices to say it, but that’s because Gorsuch keeps flying solo, and the others are still just bitter about Carpenter.’
This is how my textbook will explain things in my first Carpenter note:
From CSLI to CPLI. Carpenter concerned cell-site (essentially cell-tower) location information, and at least seven days’ duration thereof. But in Chatrie v. United States, 609 U.S. __ (2026), the Court held that two hours of differently composed cellphone location history is also protected by the Fourth Amendment: “Where the Fourth Amendment applies, it applies—regardless of the quality or quantity of information the government obtains. … Carpenter refuses to apply the third-party doctrine to CSLI, and no good reason exists to reach a different result for [Google mobile phone] Location History.”
So, the duration of government-accessed cellphone location information might matter to whether a search is reasonable (our T.L.O. final step, to which we will shortly turn), but not to whether government access constitutes a search. And we might say that Carpenter/Chatrie are together holdings not merely about cell-site location information (CSLI), but about cellphone location information (CPLI).
The Chatrie Court’s opinion, authored by Justice Kagan and joined by Justices Roberts, Sotomayor, Kavanaugh, and Jackson, does a nice job of explaining the geofence warrant and how this type of cellphone location is not meaningfully different from that in Carpenter, and how the police therefore invaded a reasonable expectation of privacy, making for a Fourth Amendment search: “An individual has a reasonable expectation of privacy in records about his cell phone’s location, and police intrude on that constitutionally protected interest when they demand the information—even though for only a limited time, and from a third-party tech company.”
So far so good. As explained in my previous post, the Court could have done further good work by striking down this warrant for effectively ceding the magistrate’s role to police and Google, but the Court decided to leave that to the lower courts in the first instance. Justice Jackson (joined by Justice Sotomayor) wrote a short concurrence to say she would have liked to do that bit more.
The Court’s opinion includes several footnotes batting away two annoyances.
One is that of Justice Gorsuch, who wrote solo—a concurrence in the judgment—because he would do away with the Katz reasonable expectation of privacy, use a dictionary-definition of “search,” and find the cell phone location information at issue to be Chatrie’s constitutionally-protected effect. In 2005, I argued for such a dictionary-definition mode, so I can’t be too harsh. Still, it’s now 2026, and I’m older and wiser, less eager to think I’m the only one to figure things out. So, the Court is skillful in giving this short shrift and looking to move the ball forward. (See Court footnote 5.)
Similar is the Court’s treatment of Justice Alito’s dissent (joined in parts by Thomas and Barrett), which both seeks to ossify the Fourth Amendment through reasonable reliance decisions (precisely what I argued against in my previous post), and which seeks a ‘Carpenter redo.’ No thanks. You lost Carpenter. Stop it already. (See Court footnotes 4 and 7.)
Having not resolved the warrant question, we’ll be here again… but we’ve moved a step in the right direction.
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