Alan Butler is senior counsel for the Electronic Privacy Information Center, which filed amici briefs in support of petitioner David Riley in Riley v. California and in support of respondent Antoine Jones in United States v. Jones.
The Supreme Court’s Fourth Amendment opinions, especially those involving new surveillance technologies, are well stocked with metaphors and similes. Lower courts are faced with the challenge of applying abstract contours of constitutional law to techniques unimaginable when previous cases were decided. Usually courts reach for similes first – “this new technique is like the old technique considered in that famous case several decades ago” – in hopes of maintaining consistency. But, more recently, the Supreme Court has relied on new metaphors to explain how to adapt old doctrine to new facts. These doctrinal course corrections are necessary where the routine application of old rules to new facts produces absurd results. We will likely see a similar correction in Carpenter v. United States.
Multiple appellate courts, including the lower court in this case, have held that cellphone location records are not protected under the Fourth Amendment because they are similar to the logs of dialed numbers that were at issue in Smith v. Maryland. The Supreme Court granted certiorari in Carpenter, despite the lack of a circuit split, to address this important Fourth Amendment question. Now the court has an opportunity to set the record straight, and should avoid the conceptual pitfalls that have bedeviled lower courts over the last decade. The court should build upon its unanimous judgments in Jones and Riley to establish strong constitutional protection for location data.
The facts in Carpenter are similar to other recent location-data cases. Law-enforcement investigators obtained several months of the defendant Timothy Carpenter’s cellphone location records without a warrant. These records were obtained from Carpenter’s cellphone providers, and included a historical log showing which cellphone towers the target phones were connected to when they made or received calls during a six-month period. Unlike some other cellphone-tracking cases, this case does not involve “real time” location tracking or the use of GPS data.
The Supreme Court has made a point in its recent decisions in Jones and Riley to reject the wooden application of decades-old Fourth Amendment precedents to modern problems. In Riley, the court declined to apply the traditional “search incident to arrest” exception to permit the warrantless search of a cellphone in the defendant’s possession at the time of arrest. In a unanimous decision, the court dismissed the notion that a cellphone was “materially indistinguishable” from a cigarette pack or a wallet (“That is like saying a ride on horseback is materially indistinguishable from a flight to the moon.”). Instead, the court found that the search of a cellphone is even more revealing than the search of a home.
In Jones, the Supreme Court considered whether the attachment and use of a GPS device to track the location of the defendant’s car was a search under the Fourth Amendment. The court had previously held in a pair of cases in the 1980s that the use of radio “beepers” to track the movement of a car on public roads over a month-long period was not a search. Some lower courts had found that a GPS tracker was like a beeper and that use of the device therefore would not trigger the Fourth Amendment. But the court unanimously rejected that conclusion, albeit under two distinct rationales. Four justices joined Justice Antonin Scalia’s majority opinion finding that the attachment of a GPS device was a physical trespass, akin to a “constable’s concealing himself in the target’s coach.” Three justices joined Justice Samuel Alito’s concurring opinion, which found that the tracking violated a reasonable expectation of privacy. Alito was skeptical of the usefulness of Scalia’s metaphor, because it “would have required either a gigantic coach, a tiny constable, or both,” but nevertheless agreed that prolonged location tracking triggered the Fourth Amendment.
In both Jones and Riley, the Supreme Court re-evaluated long held assumptions in light of new technological developments. The result in both cases was the unanimous conclusion that digital tracking and surveillance techniques trigger close Fourth Amendment scrutiny because they are more intrusive than their physical analogs. The collection of cellphone location data at issue in Carpenter v. United States is another example of changing technology that has enabled a level of intrusiveness that was impossible in an analog world. If officers can warrantlessly track every phone, then they can essentially deputize millions of tiny constables, hiding in our pockets and constantly recording our movements. Under the court’s rationale in Jones, such extensive tracking is unreasonable, but lower courts have continued to apply analog cases to this new digital problem.
Lower courts have struggled for more than a decade to determine what Fourth Amendment and statutory protections apply to cellphone location data. In particular, courts have grappled with intersecting provisions in the Electronic Communications Privacy Act (the Stored Communications Act and Pen Register Statute) and with technological developments that have continually increased the precision of location-tracking methods. Three general trends have emerged from these cases. First, some courts have drawn a distinction between historical and prospective location data, finding that warrants are only required for prospective (or “real time”) tracking. Second, courts have focused on the precision of the location-tracking method in order to “measure” the degree of intrusiveness or the privacy interest at stake. Finally, courts have relied on the holding in Smith and the content/non-content distinction to find that location data are not protected by the Fourth Amendment.
None of the concepts used by lower courts – real time vs. historical, precise vs. imprecise, and content vs. non-content – provides a principled basis for crafting a Fourth Amendment rule. The Supreme Court would be wise to avoid these distinctions because they all present major pitfalls.
First, while some courts have assumed that real-time location tracking is inherently more intrusive than collecting historical data, the opposite is actually true. Historical data is more frequently used in criminal cases because it is inherently more revealing – historical tracking can reveal patterns, associations, behaviors and other personal details that cannot be so easily derived from records in real time. It is the duration and extent of the tracking, not its temporal relationship to an investigation, that matters. Alito reached a similar conclusion in his concurring opinion in Jones, noting that “the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.”
Second, attempts to distinguish cases based on the precision of the location-tracking methods at issue have been inconsistent and arbitrary. The government has argued that collection of cellphone-tower data should not trigger Fourth Amendment scrutiny because the data do not reveal the user’s precise location. Many courts have assumed that cell-tower data are necessarily less precise than GPS data (the type of data at issue in Jones). But that assumption is wrong in many cases (tower data can be more precise than GPS data in urban areas) and is inherently short-sighted. The precision of location-tracking methods has only increased over time and will continue to do so as the density of cellphone towers increases and data analysis methods evolve. Indeed, federal law requires all cellphone providers to develop the capability to locate 911 callers precisely in an emergency.
Third, the traditional distinction between “content” and “non-content” (or “metadata”) does not map well onto location data because it does not provide a useful analytical framework for evaluating the privacy interests at stake. The Supreme Court protected the contents of the phone call in Katz v. United States even though those contents had been disclosed to another person (the recipient of the call). The fact that cellphone location records are held by a third party does not mean they are not entitled to protection. Indeed, Justice Potter Stewart recognized in his dissenting opinion in Smith that even the mere numbers dialed can reveal private facts, and thus “are not without ‘content.’” But the data generated by modern communications bear no resemblance to the minimal billing data generated by the analog telephone system in 1979.
Lower courts’ refusal to protect cellphone location data is especially troubling when, as here, Congress has already established higher privacy standards for location data in some contexts. When Congress enacted the Communications Assistance for Law Enforcement Act in 1994 at the behest of the FBI, it prohibited law enforcement from obtaining location data with a pen register (the same type of device at issue in Smith). But rather than view this statutory protection as an indication that individuals have a reasonable expectation of privacy in their location information, courts have held that cellphone-tower data are similar to the call records at issue in Smith and thus are not protected.
A better way to resolve the issue in this case is to re-evaluate Smith in light of the changes in our communications systems since 1979. Justice Sonia Sotomayor alluded to the need to do so in her concurring opinion in Jones, positing that the rule adopted in Smith is “ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks.” Even Alito’s concurring opinion in Jones implicitly recognized that long-term tracking was fundamentally different from the short-term, analog tracking methods in the 1980s beeper cases. If the Supreme Court rejects the conclusion that all personal data held by modern service providers are unprotected, and that the world has fundamentally changed since Smith was decided, then lower courts and Congress can finally begin to adopt appropriate digital-privacy rules.