What is Fourth Amendment Law Going Forward?
Last week, I blogged here at Dorf on Law about Chatrie v. United States, the Supreme Court’s first major Fourth Amendment case in eight years. Chatrie held that geofence searches, which use cellphone data to track cellphone users in a certain area at a certain time, are Fourth Amendment searches requiring probable cause and a warrant. Chatrie was a huge win for digital privacy, and it substantially expanded the scope of the Fourth Amendment. In today’s post, I’ll explain what Chatrie means for Fourth Amendment law going forward.
The Chatrie opinion potentially transformed Fourth Amendment search law in several ways. In 2018’s Carpenter v. United States, the Supreme Court held that requesting cell phone location data over a seven day period in order to track a suspect’s movements was a Fourth Amendment search requiring a warrant and probable cause. It discussed several factors that contributed to its decision, but the three that lower courts have used most frequently in the wake of Carpenter are: 1) how revealing the information is, 2) how much information is sought, and 3) whether the target voluntarily disclosed their information to a third party. In hundreds of cases decided after Carpenter, lower courts have used some or all of these factors in resolving unsettled Fourth Amendment issues. As I have argued, these factors can constitute a Carpenter test that courts can expressly adopt in frontier Fourth Amendment cases.
Chatrie modifies or destabilizes the latter two of these three factors. In doing so, it is likely to transform the law that lower courts apply to new Fourth Amendment questions. It establishes what is essentially a “Chatrie test” that courts can apply going forward. Below, I explain how Chatrie has preserved or changed the three factors of the Carpenter test.
First, the Court still plainly considers the revealing nature of data to be of paramount importance. It leads its substantive discussion of the case with a discussion of how precise and revealing Location History data is. It traces back the importance of this factor to Carpenter, characterizing it as one of the things “Carpenter relied on to find that law enforcement officers conducted a Fourth Amendment search.” It also provides several details regarding the precision of Location History, which “provides an even more fine-tuned picture of a person’s movements” than the cell site data at issue in Carpenter, tracking them to within 20 meters rather than one-eighth to four miles. The Court concludes that Location History is far more precise, and therefore far more threatening to privacy, than the surveillance in Carpenter.
The second Carpenter factor was the amount of data sought, and here the Court departs sharply from Carpenter. That prior case was replete with references to the amount of data at issue and the duration of surveillance (which is closely related in practice to the amount of data captured). In Chatrie, the Court echoes much of this language, expressing concern that the government can track someone “every moment of every day," warning against “tireless and absolute surveillance,” and noting that a person subject to warrantless retrospective surveillance (i.e. surveillance that reaches back into the past) “has effectively been surveilled [for a] boundless time.” However, the Court frames these points as more of a concern about retrospective surveillance than long-term surveillance. And it expressly criticizes the idea that some Fourth Amendment protections may kick in only once an intrusion goes too far or goes on for too long. It even contends, in a footnote, that caring about how long surveillance lasts or how much it gathers would create substantial line-drawing problems. These two concepts, that tireless surveillance is a concern and that courts should not consider how long surveillance goes on for, conflict somewhat, and they fit together oddly in the same opinion. But they can be reconciled, at least in large part.
The most faithful reading of the opinion is likely that the Court is adopting a very pro-privacy approach to the amount question. As proposed in a 2013 article by David Gray and Danielle Citron, this approach would essentially say that what matters is not how much information is gathered but whether the technology at issue has the potential to facilitate extensive and revealing surveillance. So long as a technology like geofencing might allow the police to engage in invasive long-term surveillance, then it should be treated as doing so—even if the actual duration of the surveillance in a given case is only a minute. This appears to be what the Court has in mind when it discusses the potential for boundless surveillance via geofence and then says it does not matter how long the actual geofence surveillance lasted. The Gray and Citron approach also addresses the administrability concerns the opinion raises.
Finally, there was the third Carpenter factor, which looked toward whether a person voluntarily disclosed their information to a third party. The Chatrie opinion implicitly downplays the importance of this factor, much like the Carpenter opinion, which spent only a paragraph discussing it. But Chatrie does not entirely do away with the voluntariness inquiry. Instead it transforms that inquiry. Carpenter emphasized that cellphone use was basically inescapable in modern life, and that cellphones automatically disclosed location information to cell service providers whenever they were switched on. In Chatrie, the government argued in favor of a strict, literal application of both these points. It noted that Chatrie checked yes on a permission screen during app setup and so his information disclosure was not entirely automatic. And it noted that one could easily get by in modern life without activating Google Location History.
The Court rejected these arguments in favor of a more holistic, common-sense view of the modern world. Perhaps Location History, or Google Maps itself, is not essential to life in today’s world. But this is far too narrow a view of how life works. Cellphone users use apps, if not Google Maps then another app, and in doing so they inevitably disclose personal information to service providers. This is the “price of conventional cell-phone usage,” and cellphone usage is a pervasive and insistent part of daily life. In this sense, the disclosure of location information to some company or another is not voluntary in any meaningful sense, and it is certainly not a waiver of a person’s constitutional rights. It’s the inevitable result of living in the modern world.
What, then, is left of the voluntariness prong of Carpenter? It remains somewhat uncertain, but it seems that few information disclosures will be deemed sufficiently voluntary as to threaten Fourth Amendment rights, at least based on the language and logic of Chatrie. The voluntariness inquiry after Chatrie is best interpreted to ask whether someone has disclosed their data so broadly or openly as to constitute a waiver of their rights. Perhaps overtly waiving one’s constitutional rights (not just overtly saying yes to information disclosure); or posting something for all the internet to see; or freely choosing to turn data over to the government itself would be considered sufficiently voluntary to erode a person’s constitutional protections. But simply disclosing data in the course of using the internet or a smartphone will not threaten Fourth Amendment rights.
Going forward, we can identify a “Chatrie test” to guide future cases. The test looks to three factors: 1) how revealing the information at issue is; 2) whether the surveillance technique at issue has the potential to subject people to extensive surveillance; and 3) whether the person disclosed their data so broadly or openly as to constitute a waiver of their rights. The relative importance of these factors is largely still to be determined, but revealing nature is likely to remain the most important of the three factors, as it was under Carpenter. In practice, more and more of the action of Fourth Amendment cases will be courts asking, how revealing is this surveillance practice of the details of a person’s life?, especially if we imagine the practice being used extensively for a more-or-less unlimited time. This is a very favorable inquiry for defendants arguing that the Fourth Amendment should cover a new surveillance practice. Indeed, Chatrie marks a new era in Fourth Amendment law, one characterized by robust Fourth Amendment rights in new digital contexts, and a flexible, realistic approach to data disclosures.
--Matthew Tokson