Fortunately, the government did not win the case. But the court's unanimous decision, announced on Monday, may not delay Breyer's '1984' scenario for long. Unless the court moves more boldly to restrain government use of new surveillance technologies, the Framers' notion of a private sphere protected from "unreasonable searches and seizures" will become increasingly quaint.
The case decided this week involved Antoine Jones, a Washington, D.C., nightclub owner who was convicted of cocaine trafficking in 2008 and sentenced to life in prison based largely on information that investigators obtained by surreptitiously attaching a GPS tracking device to his Jeep Grand Cherokee. All nine justices agreed that a warrant was constitutionally required for this surveillance, but they offered two different rationales.
The majority opinion, written by Antonin Scalia and joined by four other justices, emphasized the intrusion on Jones' car. "The government physically occupied private property for the purpose of obtaining information," Scalia wrote. "We 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."
The majority therefore concluded that it was unnecessary to resolve the question of whether Jones had a "reasonable expectation of privacy" regarding his travels on public roads. By contrast, the four other justices, in an opinion by Samuel Alito, said he did, given that investigators tracked all his movements for a month -- a kind of surveillance that can reveal a great deal of information about sensitive subjects such as medical appointments, psychiatric treatment and political, religious or sexual activities.
While Scalia's approach draws a clear line that cops may not cross without a warrant, it does not address surveillance technologies that involve no physical intrusion, such as camera networks, satellites, drone aircraft and GPS features in cars and smartphones. If police had tracked Jones by activating an anti-theft beacon or following his cellphone signal, they could have obtained the same evidence without touching his property.
Indeed, the court developed the "reasonable expectation of privacy" standard precisely because technologies unknown to the Framers -- telephones and eavesdropping equipment -- made it possible to secretly collect sensitive information without trespassing on the target's property. Until the 1967 case Katz v. United States, the court held that surveillance of telephone calls did not constitute a search unless it involved a physical intrusion.
But the Katz test is notoriously fuzzy. While Alito thought a month of GPS tracking was clearly a search, for instance, he said "relatively short-term monitoring of a person's movements on public streets accords with expectations of privacy that our society has recognized as reasonable." He added that even long-term monitoring might be acceptable without a warrant "in the context of investigations involving extraordinary offenses" -- a loophole big enough to drive many GPS-tracked vehicles through.
More fundamentally, the very technologies that threaten privacy also change people's expectations. "Even if the public does not welcome the diminution of privacy that new technology entails," Alito wrote, "they may eventually reconcile themselves to this development as inevitable."
But as Alito noted, there is another possible outcome: A public alarmed by the erosion of privacy can demand statutory limits on government surveillance, which then provide clear evidence of expectations "our society has recognized as reasonable." That is ultimately what happened with wiretapping, although only after the court decided that Fourth Amendment rights were at stake.
There is a chicken-and-egg problem here that reflects the circularity of the Katz test: Privacy is expected when it's protected, and it's protected when it's expected. We need to expect more, or we will end up with less.