By Christopher Dunn

A United States Supreme Court that has been systematically diluting the Fourth Amendment rights of criminal defendants dropped a bombshell last week with its unanimous ruling in United States v. Jones that police use of GPS devices on the vehicles of suspects is a search under the Constitution.

Not only is the widely reported outcome of this case big news, but the analysis in the Justices’s three opinions is full of surprise and intrigue. And the fact that this decision validates a groundbreaking 2009 ruling from the New York Court of Appeals is the icing on the cake.

Setting the Stage in New York

As GPS devices have become ubiquitous over the last two decades, the courts have been wrestling with various legal challenges to government use of the devices to monitor the movements and whereabouts of criminal suspects, government employees, and others. As of 2009, virtually every court to have addressed the issue had ruled that the use of GPS devices without a warrant on vehicles did not violate federal or state protections against unreasonable searches.

Against this backdrop, the New York Court of Appeals addressed the issue in 2009 in People v. Weaver. That case arose out of a criminal case in which prosecutors used locational data gathered from a GPS device attached to the defendant Scott Weaver’s van for 65 days. No warrant had been obtained for the device, and Weaver had moved to suppress the evidence it produced on the grounds it violated the federal and state constitutions.

In an opinion by Chief Judge Lippman, the Court of Appeals noted the unprecedented capabilities of sophisticated GPS tracking devices, explaining that with them “any person or object, such as a car, may be tracked with uncanny accuracy to virtually any interior or exterior location, at any time.” And in a passage that even the most ardent privacy advocate would be proud of, the Court highlighted the extraordinary threat to privacy that GPS devices pose:

The whole of a person's progress through the world, into both public and private spatial spheres, can be charted and recorded over lengthy periods possibly limited only by the need to change the transmitting unit's batteries. Disclosed . . .will be trips the indisputably private nature of which takes little imagination to conjure: trips to the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, the by-the-hour motel, the union meeting, the mosque, synagogue or church, the gay bar and on and on. What the technology yields and records with breathtaking quality and quantity is a highly detailed profile, not simply of where we go, but by easy inference, of our associations—political, religious, amicable and amorous, to name only a few—and of the pattern of our professional and avocational pursuits.

With these concerns in mind, the Court had little trouble concluding that the warrantless tracking of Weaver’s van for over two months in the absence of any exigent circumstances amounted to a search that required a warrant. Recognizing that the federal courts had not resolved the GPS issue under the Fourth Amendment, the Court of Appeals based its ruling entirely on the counterpart provision in the New York State Constitution. In doing so, it pointed out that it had “on many occasions interpreted our Constitution to provide greater protections when circumstances warrant and have developed an independent body of state law in the area of search and seizure.”

The Weaver ruling made national news and earned a congratulatory editorial from The New York Times. It also set the stage for the United States Supreme Court to take on the issue.

Technology and Trespass in the Supreme Court

Fifteen months after the Court of Appeals decided Weaver, the D.C. Circuit ruled that police use of a GPS device for 28 days without a warrant to track a criminal suspect violated the Fourth Amendment. When the decision came down, I rhetorically asked those involved in the case, “Who’s the fifth vote?”, as it was widely anticipated that the Supreme Court would take the case and widely feared in the civil rights community that there were not five Justices who would strike down warrantless GPS tracking. We were wildly wrong.

In the ruling issued last week, all nine Justices agreed that use of the GPS device in the case constituted a search that triggered the Fourth Amendment’s warrant requirement. Lurking behind that unanimity, however, were three separate opinions that involved surprising constellations of Justices, that took radically different Fourth Amendment approaches, and that suggested tumultuous times ahead as the Court grapples with the tension between technology and the Constitution.

By way of brief background, Fourth Amendment law underwent a significant transformation over the last one hundred years. In 1928 the Supreme Court famously held in Olmstead v. United States that a wiretap attached to an outdoor telephone line did not implicate the Fourth Amendment because there was no intrusion into the home of the person whose conversations were being intercepted. This trespass-based approach was widely criticized as being unduly formalistic and narrow, and in 1967 the Court abandoned it in Katz v. United States. At issue in Katz was a listening device attached to the outside of a phone booth (Remember them?), and the Court instead adopted an approach in which Fourth Amendment guarantees are triggered not by intrusions into physical property but rather by intrusions into “a reasonable expectation of privacy.” While this approach also has been widely criticized -- for its malleability -- it has reigned for the last four decades.

Against this background comes the GPS ruling. The majority opinion was written by Justice Scalia and joined not surprisingly by Justices Thomas, Kennedy, and Chief Justice Roberts but also joined, surprisingly, by Justice Sotomayor. In holding that use of GPS devices triggers constitutional protections, Justice Alito made no effort to decide whether there was a Katzian “reasonable expectation of privacy” in not being tracked by a GPS device.

Rather, faced with a 21st Century problem, Justice Scalia found an 18th Century solution. Contending that Olmstead’s trespass approach survived Katz, he cited an English decision from 1765 to find that use of the GPS device triggered the Fourth Amendment because “[w]e have no doubt that such a physical intrusion would have been considered a ‘search’ within the meaning of the Fourth Amendment when it was adopted” (my emphasis). And in response to the suggestion that GPS devices had no conceivable counterpart to 18th Century situations so as to allow this approach, Justice Scalia compared GPS devices to “a constable concealing himself in the target’s coach in order to track its movements.”

This uber-historical approach was harshly criticized, not surprisingly, by Justices Ginsberg, Kagan, and Breyer in an opinion written, quite surprisingly, by Justice Alito. These four Justices persuasively argued that the Court long ago had eschewed the trespass view of the Fourth Amendment and that there was no going back to the 18th Century to deal with modern technologies that threaten privacy. As for Justice Scalia’s imagined constable secreting himself in a coach for weeks on end, Justice Alito revealed a previously unseen and tart sense of humor: “[T]his would have required either a gigantic coach, a very tiny constable, or both – not to mention a constable with incredible fortitude and patience.”

Having reviewed the Fourth Amendment case law in detail and having concluded there was no avoiding assessing GPS usage under the “reasonable expectation of privacy approach,” Justice Alito and his colleagues turned to that. Though he did not go nearly as far as had the Court of Appeals in Weaver, he first recognized that a wide range of technologies – including surveillance cameras, toll-road collections systems, and cell phones – now allowed for the “precise” tracking of the movement and location of hundreds of millions of people.

As for application of the Katz standard, Justice Alito frankly acknowledged that it “involves a degree of circularity” because “judges are apt to confuse their own expectations of privacy with those of the hypothetical reasonable person to which the Katz test looks.” Nonetheless, in stark contrast to the citation-heavy dissection of Justice Scalia’s trespass analysis, Justice Scalia summarily resolved the Katz issue with the following proclamation, offered without citation to any cases, studies, or other authority:

The use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy. For such offenses, society's expectation has been that law enforcement agents and others would not—and indeed, in the main, simply could not—secretly monitor and catalogue every single movement of an individual's car for a very long period.

Finally, there is the pivotal opinion of Justice Sotomayor. On the one hand, she takes a conservative tack in that she joins Justice Scalia’s opinion. Taking on face value his claim that his 18th Century trespass approach is intended to add to and not supplant the reasonable-expectation-of-privacy test of Katz, Justice Sotomayor seems content to sign on to an opinion that ostensibly adds to Fourth Amendment protections without having to decide complicated questions about how privacy-shrinking technologies fit with the Katz approach.

On the other hand, Justice Sotomayor suggests -- without deciding -- that a radical reconceptualization of the Fourth Amendment may be in order to account for those technologies. At the outset, she highlights the extraordinary invasive potential of even short-term GPS monitoring, citing and quoting the Court of Appeals’s discussion in Weaver about tracking trips to psychiatrists, abortion clinics, AIDS treatment centers, churches, and other acutely private activity. And in applying the Katz analysis, she says she would “ask whether people reasonably expect that their movements will be recorded and aggregated in a manner that enable the Government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on.” She also said she would consider the appropriateness of entrusting to the police “a tool so amenable to misuse,” particularly in light of the Fourth Amendment goal of curbing “a too permeating police surveillance.”

Given the burgeoning tracking potential in the digital age and given the potential for abuse, Justice Sotomayor argues it may be necessary to adopt a much broader view of the Fourth Amendment that protects information even if it is not kept secret. In other words, she argues that the fact that technology in the modern world is ever shrinking our expectations of privacy should not mean that our Fourth Amendment protections should likewise be shrinking. As she put it, Fourth Amendment jurisprudence may need to cease treating “secrecy as a prerequisite for privacy.”

Looking Forward

The Court’s GPS decision aptly illustrates the difficulties courts face in trying to adapt the law to fundamental societal change. Were 21st Century police tracking of our every movement not such a serious matter, it would just be funny to think that Supreme Court Justices are deciding these issues by imagining constables hiding in 18th Century coaches.

Hidden constables aside, the Court’s decision leaves open many difficult questions that will have to be answered as privacy-shrinking technologies advance even further. What about technologies that do not require the attachment of a device to a vehicle and thus present no possible trespass? What about police access to information gathered by GPS devices installed by car manufacturers and rental car companies of which drivers are fully aware and thus cannot claim trespass or an expectation of secrecy? And what about all those smart phones so many are carrying around that, as most people realize, contain sophisticated GPS systems?

In Jones members of the Supreme Court acknowledged all these issues, but the Court resolved none of them. But they need to be resolved, as they are upon us now. And as Justice Sotomayor suggests, resolving these types of issues may require another fundamental shift in Fourth Amendment jurisprudence.

Christopher Dunn is the associate legal director of the New York Civil Liberties Union.