WASHINGTON In a unanimous decision, the Supreme Court ruled Monday that police cannot attach a GPS device to a criminal suspect's car to track their movements without first obtaining a search warrant.
A GPS device had helped authorities link Washington, D.C., nightclub owner Antoine Jones to a suburban house used to stash money and drugs. He was sentenced to life in prison.
A federal appeals court in Washington had overturned Jones' drug conspiracy conviction because police did not have a warrant when they installed a GPS device on his vehicle and then tracked his movements for a month.
The Supreme Court agreed.
Associate Justice Antonin Scalia said that the government's installation of a GPS device, and its use to monitor the vehicle's movements, constitutes a search, meaning that a warrant is required.
"By attaching the device to the Jeep" that Jones was using, "officers encroached on a protected area," Scalia wrote.
CBS News legal analyst Andrew Cohen said today's decision was a victory for civil libertarians and a defeat for law enforcement officials who had argued that putting a GPS device on a car wasn't exactly a search under the Fourth Amendment.
"Perhaps the biggest surprise is that the justices were unanimous," said Cohen. "All of the Justices agreed that placing a GPS monitor on a suspect's car triggered the protections of the Fourth Amendment's protections against unreasonable searches and seizures. But the Court didn't say whether the search here was reasonable or not."
Scalia wrote the main opinion of three in the case. He was joined by Chief Justice John Roberts and Justices Anthony Kennedy, Clarence Thomas and Sonia Sotomayor.
Sotomayor also wrote one of the two concurring opinions that agreed with the outcome in the Jones case for different reasons.
Justice Samuel Alito also wrote a concurring opinion in which he said the court should have gone further and dealt with GPS tracking of wireless devices, like mobile phones. He was joined by Justices Ruth Bader Ginsburg, Stephen Breyer and Elena Kagan.
The case is U.S. v. Jones, 10-1259.
Cohen thinks the case, or one like it, may come before the court again, "because the justices did not rule on whether the exact search here was reasonable. In other words, even if the Fourth Amendment applies, it's possible that the use of GPS devices COULD be considered constitutional in SOME circumstances."