Today the U.S. Supreme Court unanimously ruled that police need a search warrant before they can track a suspect's movements by attaching a GPS device to his car. The case involved a Washington, D.C., nightclub owner, Antoine Jones, who was convicted of cocaine trafficking and sentenced to life in prison based largely on information police obtained through GPS tracking of his Jeep. In 2010 the U.S. Court of Appeals for the D.C. Circuit overturned Jones' conviction, ruling that the warrantless tracking violated the Fourth Amendment's ban on "unreasonable searches and seizures." Upholding that decision today, the Supreme Court ruled that the physical intrusion on Jones' car required to attach the tracking device represented the sort of trespass that was meant to be covered by the Fourth Amendment, which applies to people's "effects" as well as their homes. The majority, in an opinion by Justice Antonin Scalia that was joined by four other justices (John Roberts, Anthony Kennedy, Clarence Thomas, and Sonia Sotomayor), said it was therefore unnecessary to address the question of whether Jones had a "reasonable expectation of privacy" regarding his public movements. Justice Samuel Alito wrote a concurring opinion, joined by three other justices (Ruth Bader Ginsburg, Stephen Breyer, and Elena Kagan), that said Jones did have a reasonable expectation of privacy in the information collected via GPS tracking of his car:
Relatively short-term monitoring of a person’s movements on public streets accords with expectations of privacy that our society has recognized as reasonable….But the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy. 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 catalogue every single movement of an individual’s car for a very long period/ In this case, for four weeks, law enforcement agents tracked every movement that [Jones] made in the vehicle he was driving. We need not identify with precisionthe point at which the tracking of this vehicle became a search, for the line was surely crossed before the 4-week mark.