The US Supreme Court ruled unanimously Monday that police must obtain a search warrant before using a GPS device to track criminal suspects. But the decision was narrow, leaving unanswered lingering questions about citizens' expectations of privacy in an age of rapid technological advance.
Writing the majority opinion, Justice Antonin Scalia said police needed a search warrant before attaching a GPS device to a suspect's vehicle. He was joined in the opinion by Chief Justice John G. Roberts Jr. and Justices Anthony M. Kennedy, Clarence Thomas and Sonia Sotomayor.
"We hold that the government's installation of a GPS device on a target's vehicle, and its use of that device to monitor the vehicle's movements, constitutes a 'search'" under the Fourth Amendment's protection against unreasonable searches and seizures, Scalia wrote.
But the court split on whether the decision went far enough. Scalia wrote that if the government had been able to use electronic surveillance to spy on Jones without physically trespassing on his property, that may have been "an unconstitutional invasion of privacy." But, Scalia added, "The present case does not require us to answer that question."
That wasn't good enough for Justice Samuel Alito Jr., who, in a concurring opinion, said the court should have tackled the larger question instead of using "18th century tort law" to decide a case about "21st century surveillance techniques."
"The court's reasoning largely disregards what is really important (the use of a GPS for the purpose of long-term tracking) and instead attaches great significance to something that most would view as relatively minor (attaching to the bottom of a car a small, light object that does not interfere in any way with the car's operation)," Alito wrote.
It was the long-term surveillance itself, not the fact that police physically placed a tracking device on Jones' vehicle, that violated the Fourth Amendment's proscription against warrantless searches and seizures, Alito argued.
"The use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy," he wrote. "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 catalog every single movement of an individual's car for a very long period."
Although Justice Sotomayor joined the majority opinion, she also seemed disappointed that the court had not ruled more broadly. She wrote that the court had in effect ducked the big question of whether warrantless electronic surveillance was constitutional and warned that Monday's decision will do little to answer that question.
"With increasing regularity, the government will be capable of duplicating the monitoring undertaken in this case by enlisting factory- or owner-installed vehicle tracking devices or GPS-enabled smart phones," Sotomayor wrote. "In cases of electronic or other novel modes of surveillance that do not depend upon a physical invasion on property, the majority opinion's trespassory test may provide little guidance."
Still, this is a win for the Fourth Amendment and for individual privacy rights, even if it is limited.