Holding: Attaching a GPS device to a vehicle and then using the device to monitor the vehicle's movements constitutes a search under the Fourth Amendment.
Judgment: Affirmed, in an opinion by Justice Scalia on January 23, 2012. Justice Sotomayor filed a concurring opinion. Justice Alito also filed a concurring opinion, which was joined by Justices Ginsburg, Breyer, and Kagan. The five concurring members of the Court do not resolve the question of whether the search was reasonable in this case.
-- SCOTUS opinion in United States v. Jones, 23 January 2012