Today, the U.S. Supreme Court concluded that if police attach a Global Positioning System tracking device to a car, the Fourth Amendment requires that they get a warrant to do so. The decision, United States v. Jones, protects privacy rights against one intrusive way the police use GPS technology and answers a question the Wisconsin Supreme Court sidestepped in State v. Sveum in 2010.
“Police should have probable cause that a crime has been or is likely to be committed before using GPS tracking technology,” said ACLU of Wisconsin Executive Director Chris Ahmuty. “The ACLU of Wisconsin agrees that without a judge’s agreement, police use of warrantless GPS tracking would be a violation of our Fourth Amendment rights. The details of our private lives are revealed by our movements. Allowing police the power to obtain information on the location of anyone's car and movements, for any reason or for no reason at all, without a valid warrant, is unconstitutional.”
In February 2010, the ACLU and the Electronic Frontier Foundation (EFF) filed a friend-of-the-court brief (PDF) with the Wisconsin Supreme Court in State of Wisconsin v. Sveum, urging the Court to hold that attaching a GPS device was a "search or seizure" requiring a warrant under the Wisconsin constitution as well as the Fourth Amendment. The brief warned that approving warrantless GPS could allow police to engage in fishing expeditions to obtain a detailed picture of someone's personal associations by identifying the churches, bars, protests or doctor's offices a person visited.
In its decision in July 2010, the Wisconsin Supreme Court sidestepped the question of whether there are any constitutional limits on police use of global positioning system devices to track people in their cars. Instead, the state's high court decided that a court order obtained by the police satisfied the warrant requirement of the Fourth Amendment.
Today's unanimous decision by the U.S. Supreme Court emphatically answers the question the Wisconsin courts left open: the Fourth Amendment protects privacy against intrusive GPS tracking.