The Volokh Conspiracy
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Carpenter v. United States and the positive law model
Another Supreme Court case I've been following this fall is co-blogger Orin Kerr's favorite, Carpenter v. United States. As folks will know from reading Orin's blog posts or his superb amicus brief, the case asks whether it is a search for the government to obtain historical cell-site location data from your wireless provider. His most recent post, over at Lawfare, criticizes both Carpenter's heavy reliance on the "mosaic theory" and some relatively arbitrary line-drawing required by that theory.
So I thought I would pop in to emphasize that there is an alternative theory that Carpenter has put forward, one that may avoid a lot of line-drawing problems and also has deep grounding in the history, structure and purpose of the Fourth Amendment. That theory is the Positive Law Model of the Fourth Amendment, which I wrote about (with my co-author James Stern) last year in the Harvard Law Review. (Our friend Richard Re has also put forward a related theory, the Positive Law Floor.)
In a nutshell, under the positive law model, it is a search for the government to gather information in a way that a similarly situated private party would not be allowed to do. This, we argue, is why government trespasses into the home are such paradigmatic examples of a Fourth Amendment search—the Fourth Amendment requires the government to justify itself before it can transgress generally applicable positive law rights.
With that, I just wanted to make three quick points about the positive law model and the Carpenter case.
1. The positive law model is a plausible alternative to both the absolutist third-party doctrine and the mosaic theory. Many people, and I suspect quite a few of the justices, seem to have the intuition that there is something unsatisfying about current precedents on the third-party doctrine, especially if they are extended into the modern digital realm. At the same time, I can see why they might be worried about replacing the third-party doctrine with a judicial line-drawing approach, such as the mosaic theory.
The positive law model can provide an attractive alternative to both. The positive law model provides limits to the government's ability to warrantlessly gather electronic information held by telecommunications companies and other third parties. But the court won't need to engage in endless and arbitrary line-drawing exercises to figure out what those limits are. They will be the very same limits that already apply to everybody else. Using positive law as a baseline could assuage a lot of worries about line-drawing and what comes next.
2. Under the positive law model, Carpenter should probably win. As Richard Re has explained at his blog, Re's Judicata, the activity in this case does seem to violate Carpenter's generally applicable positive law rights:
Congress has provided that "[e]very telecommunications carrier has a duty to protect the confidentiality of proprietary information of, and relating to, … customers." 47 U.S.C. § 222(a); § 222(c). And the WCPSA defined "customer proprietary network information" to include "information that relates to the … location … of use of a telecommunications service subscribed to by any customer of a telecommunications carrier, and that is made available to the carrier by the customer solely by virtue of the carrier-customer relationship." § 222(h). The WCPSA also established a special "express" consent requirement specifically for disclosure of customer location information. § 222(f).
There are certain statutory exceptions to these protections, see § 222(c) & (d), but the only one that seems applicable in Carpenter is a general reference to disclosure "as required by law." In several cases, the government has argued that that exception allows for disclosure orders like the one in Carpenter. See 2012 WL 604860 at 29-30 (discussing 18 U.S.C. § 2703). But that kind of government-only exception is precisely what triggers the positive law model or floor: the point of those approaches is to provide a constitutional check on the government's access to information that is denied to similarly situated private parties.
Further, the WCPSA is linked to a cause of action for individuals. See 47 U.S.C. § 207. That provision is important because government exceptionalism may not be enough to secure protection under the positive law model or floor: in addition to violating laws applicable to similarly situated private parties, the government may have to violate a personal legal right of the defendant himself. By treating locational information as a customer's "proprietary information" and affording customers a cause of action, Congress seems to have signaled that the defendant did indeed have a personal right to locational privacy.
The government's main response to this point in its brief (at p. 42-43) is that the statute gives the government certain powers to compel disclosure. That is true, but non-responsive. As Re points out, under the positive law model, what matters is precisely whether the government is availing itself of some government-specific power as against the generally applicable law. If a state enacted an amendment to trespass law that allowed police to come into your house without a warrant, that wouldn't change the baseline for constitutional searches. The same is true here.
3. You don't have to commit to one precise version of the positive law model to use it in this case. There are several different theories of how exactly Fourth Amendment doctrine should avail itself of the positive law model. James and I put forward one theory; Re put forward a different one, in which positive law is a presumption rather than a rule and serves as a floor to Fourth Amendment rights but not a ceiling. One could also filter the positive law model through the "reasonable expectation of privacy" test more generally, or through the Jones and Jardines trespass cases in particular.
But in Carpenter, all of these roads lead to the same place, and the court doesn't really have to commit itself to any one of them in particular. All it would have to say is that in this case, a reason not to apply the third-party doctrine is the strength of Carpenter's positive law rights. And/or it could say that the trespass principle of Jones and Jardines generalizes beyond the physical objects (the car and the house) at issue in those cases, to include, in the electronic realm, the equivalent violations of positive law. It could even, as in Jones and Jardines, assemble a coalition of justices that combines those who emphasize the importance of the positive law/trespass principle and those who emphasize the importance of Katz v. United States and their view of reasonable expectations.
This would open up the basic inquiry that the third-party doctrine has been thought to close off and provide guidance about the basic framework to the lower courts but still leave some issues for further percolation. While of course I would love to see widespread agreement with my own version of the theory, this might nonetheless be the most judicious course.