On Tuesday the U.S. Supreme Court considered whether the Fourth Amendment requires police to obtain a warrant before they use a GPS device to track a suspect's vehicle. The case involves Antoine Jones, a Washington, D.C., nightclub owner who was convicted of conspiring to sell cocaine and sentenced to life in prison based largely on information about his movements collected via a GPS tracker that police surreptitiously attached to his car. Although the cops actually had a warrant to track Jones (which suggests that requiring one in such circumstances is not an intolerable burden), it expired before the surveillance began. Hence the question is whether they needed one to begin with.
The U.S. Court of Appeals for the D.C. Circuit thought so (PDF). Writing for the majority last year, Judge Douglas Ginsburg distinguished the tracking of Jones, which continued 24 hours a day for a month, from the use of a radio transmitter ("beeper") to help police follow a car, which the Supreme Court has said does not require a warrant:
The Court explicitly distinguished between the limited information discovered by use of the beeper—movements during a discrete journey—and more comprehensive or sustained monitoring of the sort at issue in this case….Most important for the present case, the Court specifically reserved the question whether a warrant would be required in a case involving twenty-four hour surveillance, stating, "if such dragnet-type law enforcement practices as respondent envisions should eventually occur, there will be time enough then to determine whether different constitutional principles may be applicable."
Ginsburg noted that the capabilities of modern tracking technology far outstrip what can feasibly be accomplished by human observers in public:
We hold the whole of a person's movements over the course of a month is not actually exposed to the public because the likelihood a stranger would observe all those movements is not just remote, it is essentially nil. It is one thing for a passerby to observe or even to follow someone during a single journey as he goes to the market or returns home from work. It is another thing entirely for that stranger to pick up the scent again the next day and the day after that, week in and week out, dogging his prey until he has identified all the places, people, amusements, and chores that make up that person's hitherto private routine.
During Tuesday's oral arguments (PDF), at least four justices (John Roberts, Stephen Breyer, Ruth Bader Ginsburg, and Sonia Sotomayor) seemed troubled by the amount of information that can be collected through GPS tracking. "If you win this case," Breyer told Deputy Solicitor General Michael Dreeben, "then there is nothing to prevent the police or the government from monitoring 24 hours a day the public movement of every citizen of the United States," which "sounds like 1984." Dreeben replied that we can worry about that when it happens.
Two justices, Samuel Alito and Antonin Scalia, wondered whether it was possible to draw a nonarbitrary line between acceptable public monitoring and a Fourth Amendment violation. In a recent ABA Journal essay about Jones, Erwin Chemerinsky, dean of the U.C.-Irvine law school, argues that the problem is the "reasonable expectation of privacy" standard that the Court applies in Fourth Amendment cases:
One key problem with the "reasonable expectation of privacy" test is that the government seemingly can extinguish it just by telling people not to expect any privacy in a particular area.
Moreover, focusing on the reasonable expectation of privacy confuses a description of what people think it should be with a conclusion about what the Fourth Amendment should be deemed to protect. Whether people actually have an expectation of privacy in a particular instance is an empirical issue that can be measured.
But that is never how courts decide whether a reasonable expectation of privacy exists. Courts make an intuitive sense about whether people expect privacy in particular instances. But the question should not be about what people actually expect, but what they should be entitled to expect under the Fourth Amendment.
The Court could avoid opening this can of worms by ruling that installing the GPS tracker involved a physical intrusion on Jones' property (i.e., his car) that itself required a warrant, regardless of the information that was later collected. But that solution would not apply to surveillance that requires no physical intrusion, such as pervasive public monitoring via cameras mounted on poles, drone aircraft, or satellites.
[Thanks to Mark Sletten for the Chemerinsky link.]