By Seth Stodder

This week, the Supreme Court dipped its toes into the muddy waters of how modern surveillance technologies – in this case, GPS tracking – fit within the 200 year old confines of the Fourth Amendment. The answer – provided by the Court in a decision as murky as those legal waters are muddy – is they fit pretty uncomfortably.

In United States v. Jones, the Court ruled that the DC Police and the FBI violated the Fourth Amendment when they placed a GPS tracker on a Jeep Cherokee driven by criminal suspect Antoine Jones, and then tracked it for 28 days – all without a valid search warrant. The Justices’ three competing opinions in the case, however, raise more questions than they resolve – and point to many legal battles to come as courts wrestle with whether and to what degree 21st Century surveillance and analytics capabilities should be circumscribed by constitutional principles. Suffice it to say that in the wake of Jones, officers should probably get a warrant if they want to use technology, such as GPS or even CCTV, to persistently monitor anyone for any substantial length of time – at least in the context of a criminal investigation. (It is unclear whether an intelligence operation or one aimed solely at disrupting or preventing a terrorist attack might warrant a different conclusion.) The decision also potentially puts an light asterisk by sophisticated data analytics tools, to the extent they draw upon large data sets of public or privately-held information to develop a “mosaic” picture of a potential suspect.

The main opinion of the Court – authored by Justice Scalia and joined by Chief Justice Roberts and Justices Thomas, Kennedy and (to some extent) Sotomayor – decided the case on an almost comically narrow ground. In Scalia’s view, because the government placed the tracker on Jones’ private property (the Jeep), this was essentially a “trespass” onto one of his “effects,” and therefore a “search” under the Fourth Amendment. (And, because the government failed to argue in the lower courts that such a trivial warrantless “search” was still reasonable, the government could not raise it before the Supreme Court and lost the case.)

In drawing the conclusion that the installation of the GPS tracker was a “search,” the Court’s main opinion entirely avoided the big issue addressed by the lower court below – namely, whether the lengthy GPS surveillance of Jones’ movements on public streets (as opposed to simply the installation of the tracker on Jones’ vehicle) interfered with Jones’ constitutional privacy rights. In its ruling, by contrast to Justice Scalia’s, the DC Circuit was far more sweeping, concluding that the warrantless GPS surveillance itself was unconstitutional (not merely the installation of the tracker). In the DC Circuit’s view, the continuous technological tracking of Jones’ movements “24 hours a day for 28 days as he moved among scores of places” did constitute a “search” under the Fourth Amendment because Jones had a reasonable expectation of privacy in the sum total of his movements on public streets over such an extended period.

In reaching this conclusion, the DC Circuit rejected the government’s arguments that GPS tracking of a vehicle’s movements was not an invasion of privacy because the vehicle’s movements were on public streets; and that the surveillance was akin to having police officers actually watch such movements, saying that the difference was the technology’s ability to reveal the totality of a person’s movements over a lengthy period of time – something a group of officers’ naked eyes could not achieve. So, in other words, while continual visual surveillance by officers for some short period of GPS tracking would be OK, too much GPS tracking over too long of a period – even if the GPS is simply tracking where a vehicle drives on public streets – is too much like “Big Brother” and requires a warrant.

The DC Circuit thus broke significant new ground in how courts might draw the correct balance between enforcement and privacy under the Fourth Amendment. Its essential conclusion that the totality of a person’s movements on public streets could at some point be deemed within that person’s reasonable zone of privacy conceivably calls into question all technologies permitting persistent surveillance in public places – not just GPS trackers, but also CCTV cameras, satellites, among other things. For instance, under the DC Circuit’s formulation, are the matrix of CCTV cameras deployed in lower Manhattan – to the extent they could be used to track a person’s movements in the area over a lengthy period of time (a la “24” or “Minority Report”) – constitutionally suspect? What about data analytics capabilities, drawing upon all available bits and bytes of information, that can present a total picture of a person’s activity in society (such as financial transactions, drives through toll booths, among other things)? Are law enforcement data analytics tools now constitutionally suspect? What about facial recognition capabilities?

Tough questions all. No wonder Justice Scalia’s opinion reads like a Houdini act, twisting its way out of having to reach into the legal can of worms the DC Circuit had opened. In that way, Scalia’s reliance on 18th century property tort law – instead of tangling with how 21st century surveillance technologies can be balanced with privacy rights – has to be viewed as one of the great Supreme Court “punts” of all time.

And in that sense, the opinion ends up being unsatisfying – as Justice Alito’s concurrence (joined by liberal Justices Breyer, Kagan, and Ginsburg) aptly points out, along with pointing out all kinds of other questions raised by Justice Scalia’s “trespass to chattels” theory (such as, which of the 50 states’ tort laws would apply to interpreting the Fourth Amendment in cases involving government touching private “effects,” or what if a GPS tracker did not work – would it still be a “search”?).

But Justice Alito’s concurrence raises even more thorny questions. His opinion essentially agrees with the DC Circuit’s sweeping view of privacy rights in the public sphere, expressing significant concern over “the emergence of many new devices that permit the monitoring of a person’s movements.” In addition to the GPS tracker at issue in the case, Justice Alito also points to GPS trackers in smart phones and other wireless devices – asserting that the surveillance capabilities that these devices permit will no doubt need to shape the law’s concept of what a reasonable expectation of privacy should be, even with regard to movements in the public sphere.

Thus, Justice Alito would have rejected the government’s case on much the same grounds as those asserted by the DC Circuit – namely that, at some point and in some cases, persistent surveillance by GPS tracking requires a warrant. Justice Alito, however, provides no guidance as to where to draw the line between what degree of technological surveillance would require a warrant, and which would not. He also adds the additional curveball that there may be cases involving “extraordinary offenses” where prolonged warrantless GPS monitoring may be permissible. So, in a shoplifting case, a month of warrantless GPS tracking would be unconstitutional, but in a terrorism case, it might be permissible? Unclear. What about an intelligence operation aimed at preventing a terrorist attack? Would this be treated differently than, say, the GPS tracking in the Jones case? Unclear.

Justice Sotomayor’s solo concurrence provides perhaps the most clarity – although it is the most extreme. She agrees with Justice Scalia’s main opinion that the installation of the GPS tracker on the private vehicle itself constituted a “search,” but she also would go further than Justice Alito, asserting that conceivably any GPS monitoring (even short term) might tread upon reasonable privacy interests, and therefore require a warrant.

She goes even further, however, with this bombshell – asserting that “it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties.” For decades, it has been black-letter law that if you voluntarily provide information to a third party – such as your financial information to a bank, or texts you type on your Verizon smart phone, or search terms you plug into a Google search engine – you have no Fourth Amendment right to prevent government from obtaining that information from the third party (although, in certain circumstances, you may have statutory rights of privacy). Given 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,” Justice Sotomayor would revisit that long-standing principle – which would revolutionize the entire area of the law, and call into constitutional question any number of standard law enforcement or intelligence tools, such as National Security Letters, business record subpoenas under the Patriot Act, requests for old communications under the Stored Communications Act, among many other things. Wow.

So, what’s the upshot of Jones? As noted, the main opinion of the Court is extremely narrow – holding only that when government places a GPS tracker on an individual’s private vehicle, this is a “search” under the Fourth Amendment that might (but might not) require a warrant, at least in a criminal case. (As noted, it is unclear whether Jones would apply in a national security or intelligence/counterterrorism operation.) That said, there are five Justices – Sotomayor, Alito, Breyer, Ginsburg, and Kagan – who are on record saying that persistent GPS surveillance, and conceivably any use of technology that draws upon capabilities beyond normal human senses to persistently watch individuals, is potentially subject to Fourth Amendment scrutiny.

Needless to say, the three opinions in Jones raise more questions than they resolve, and lower courts over the next decade will be trying to figure them out. But make no mistake – Jones is a watershed decision, and officers better start writing some warrant applications.