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Orin Kerr on Carpenter v. United States
Michael Ramsey

At Lawfare, Orin Kerr: Four Thoughts on the Briefing in Carpenter v. United States (Carpenter v. United States, the cell-cite records case, will be argued next week, on Nov. 29th).

On the so-called "mosaic" theory: 

The most striking aspect of the briefing in the case is that Carpenter goes all-in on the mosaic theory of the Fourth Amendment. He concedes that short-term monitoring of historical cell-site records -- or rather, collection of historical cell-site records covering a short period of time -- is not a search. In his view, collection of cell-site records becomes a search only when the time period of the collection is "longer term."

I've written, both in an article and in Section III of my brief, about the enormous headaches that such a mosaic approach would create. Notably, Carpenter avoids taking a position on how to implement this theory until the reply brief. In the reply brief, he finally takes a view on just the starting question -- how long is longer term -- by offering a 24-hour standard.


Once you start to answer all the questions that implementing the mosaic approach requires you to answer, it quickly becomes clear that you're really drafting a statute. It would be sort of a Miranda on steroids: You'd need to make a few dozen essentially arbitrary line-drawing calls. You can do that. But you'd look a bit silly. It's hard to announce all of those lines without making clear that you're more legislating than interpreting anything in the Constitution. ...

And on the so-called "equilibrium-adjustment" theory: 

I think Carpenter's position is misguided, but his basic theory is the most direct and clear argument for equilibrium-adjustment that I have seen articulated in a legal brief. As some readers know, I have argued that the Court does and should update Fourth Amendment rules to maintain the balance of government power as technology changes. The idea that is that some technological shifts so transform the level of government investigative power (whether expanding it or restricting it) that they justify new rules to restore the prior level of government power. I have called this "equilibrium-adjustment," as the court adjusts the legal rule to restore the prior equilibrium.

With that background, consider how Carpenter frames his constitutional claim:

As new technology has dramatically lowered the cost of government surveillance and increased the government’s access to private information, this Court has stressed that the reasonable-expectation-of-privacy inquiry must “assur[e] preservation of that degree of privacy against government that existed” prior to the advent of the new technology in question. United States v. Jones, 565 U.S. 400, 406 (Scalia, J.) (alteration in original)

This is a bit of a fudge, as the quote from Jones, in turn quoting Kyllo, was actually that "we must assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted" (emphasis added). The sentence was making an originalist claim, looking back to the 18th century, not making an equilibrium-adjustment claim, looking back to before the technology became widespread. Still, it's a fudge that makes the equilibrium-adjustment argument particularly clear. As I wrote back in 2012, I think the mosaic theory is the wrong way to engage in equilibrium-adjustment. But I personally liked how clearly Carpenter relied on equilibrium-adjustment in his brief.

RELATED:  Professor Kerr also has this Carpenter-related shorter post at Lawfare: The Fourth Amendment Doesn't Recognize a General "Right to be Secure".  Core point:

That text does not provide for some sort of general “right to be secure.” Rather, the text is much more specific. It states that “the people” have a right “to be secure” in particular things (“in their persons, houses, papers, and effects”) against something specific (“unreasonable searches and seizures”). In ordinary language, if you have a right to be secure against some specific bad thing, you don't have a general right to be secure. You just have a right to be secure against that specific bad thing. Your right is violated if the bad thing happens. If the bad thing doesn't happen, your right isn't violated.

Agreed, and I think this suggests (as an originalist matter) that Carpenter should lose: the cell-site data is not his papers or effects -- it belongs to a third party.  (This is the "third party doctrine" adopted by the lower court, see here).  Professor Kerr made this point back when the Court agreed to hear the case -- see here:

Here’s the opening text of the Fourth Amendment:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated[.]

As Justice Antonin Scalia emphasized in his concurrence in Minnesota v. Carter, the word “their” can be understood as important in historical context. It signals that to assert a Fourth Amendment violation, a person’s own self, houses, papers or effects must be unreasonably searched or seized.

But I also think the Court is more likely to favor some sort of updating or "equilibrium-adjustment" approach, and it can appeal to Scalia in the Kyllo case (as Carpenter's brief does) in support.