When analogies fail

2017 is here. We are now part way between the idyllic 2015 depicted in "Back to the Future II" and the dystopian 2019 portended in "Blade Runner." Neither prognostication got it completely right, but both accurately predicted the continued advance of technology.

Integrating this seemingly unstoppable advance into the law that reflects and defines our society and its values is another thing entirely. Nowhere is the challenge more public than in the U.S. Supreme Court's efforts to apply the Fourth Amendment to new technologies.

In undertaking these efforts, the Supreme Court has relied on one of the most trusty of tools in a lawyer's (or judge's) toolbox ? reasoning by analogy. Three recent cases illustrate this point.

Florida v. Jardines, 133 S. Ct. 1409 (2013), presented the following question: Does the cops' use of a drug-sniffing dog on a suspect's front porch constitute a "search" subject to the Fourth Amendment's strictures? The justices seemingly had two competing analogies from which to choose. A dog sniff of a porch is like a dog sniff of luggage, and United States v. Place, 462 U.S. 696 (1983), held that the latter is not a "search." Alternatively, a dog sniff is the biological equivalent of a mechanical, sense-enhancing device (a "Smell-O-Matic," as Justice Elena Kagan called it at oral argument), and Kyllo v. United States, 533 U.S. 27 (2001), held that police use of such a device constitutes a "search" unless the device is in general public use. The Jardines majority did not choose between the analogies, opting instead to rest its ruling on the Fourth Amendment's property rationale.

United States v. Jones, 565 U.S. 400 (2012), asked whether police installation of a GPS tracking device on the car defendant drove for 28 days constituted a "search." The government argued that the use of a GPS device was no different than tailing a car on public roads, which the Supreme Court held in United States v. Knotts, 460 U.S. 276 (1983), did not implicate the Fourth Amendment. The majority opinion decided the case on the ground that placement of the GPS device on the car constituted an invasion of a common law property interest. But Justice Samuel Alito and four other justices ? in two separate concurring opinions ? examined the privacy question and, in so doing, questioned the analogy between a GPS device and a tail, noting it was "almost impossible to think of" an "analogous" "late-18th-century situation[]" unless the suspect had a "gigantic coach" or was tailed by "a very tiny constable."

And Riley v. California, 134 S. Ct. 2473 (2014), examined whether police could search a cellphone incident to arrest without any additional cause or a warrant. The government urged that a cellphone was like any other object on a person that was subject to search upon arrest under United States v. Robinson, 414 U.S. 218 (1973). But eight justices disagreed, explaining that the analogy did not hold because cellphones themselves stored and integrated vast quantities of data and, to the extent cellphones stored data elsewhere, were "like finding a key in a suspect's pocket and arguing that it allowed law enforcement to unlock and search a house."

In answering these questions, the Supreme Court has taken two approaches. In Jardines and Jones, as noted above, the majority decided the question by using the Fourth Amendment's property rationale, concluding that the police conduct at issue constituted a "search" because it violated the suspect's common law property rights. This reasoning obviated the need to confront the Fourth Amendment's privacy rationale and the competing analogies relevant to that rationale. Only Justice Alito's concurrence in Jones and the majority opinion in Riley confronted the analogies themselves and, in each case, concluded that the conduct constituted a "search" because the relevant analogy to earlier technology broke down. Indeed, the Riley decision went so far as to reject the government's fallback argument that the court should evaluate each item seized incident to arrest and require a warrant only for those items lacking "a pre-digital counterpart."

But will these approaches continue to work as new technologies are invented and put into use?

The Supreme Court's resort to the Fourth Amendment's property rationale was available in Jardines and Jones because each involved a physical trespass. As Justice Alito asked in his Jardines dissent, what if the drug-sniffing dog alerted while on the public sidewalk in front of Jardines' home? And, as Justice Alito asked in Jones, what if the tracking device was factory-installed and triggered automatically upon a vehicle's theft? In either case, there is arguably no physical trespass by law enforcement and hence the Fourth Amendment's property rationale offers no solace.

The Supreme Court's reliance on analogies may also become more strained as technology requires the use of more and more fantastical and unrealistic analogies. If GPS devices are analogous to "very tiny constables" hitchhiking on a car's chassis, what about unmanned aircraft systems (aka drones), through-the-wall radar, and enhanced-reality glasses? All are available to law enforcement. Are drones to be likened to very tiny constables with wings and cameras? Is through-the-wall radar to be compared to a (normal-sized) constable with X-ray, super-vision? Are enhanced-reality glasses that are worn by officers and can measure and digitally log traffic violations to be seen as a constable with precise vision and an eidetic memory?

What, then, are courts to do?

They could, as Riley did, apply the Fourth Amendment whenever there is no ready analogy to lower-tech police conduct that already falls outside the Fourth Amendment's reach. Or courts could stop looking for analogies as a descriptive measure of the intrusiveness of a particular technology under the Fourth Amendment's privacy rationale, and instead define the boundaries of privacy normatively by specifying what those boundaries should be. In other words, courts could stop defining privacy by looking to what people in the real world actually expect and instead define it by examining the level of privacy people should expect. Or courts could adopt an entirely new rationale for the Fourth Amendment that does not look to privacy at all, and define the amendment's scope by some new and different paradigm.

Only time will tell which of these paths the Supreme Court will take. Let us hope that this future gives us a satisfying and useful answer. And some hover boards.