The Supreme Court has decided that law officials must get a warrant before attaching a GPS device to someone’s car. Justice Antonin Scalia wrote the Court opinion, in which Chief Justice John Roberts and Justices Anthony Kennedy, Clarence Thomas, and Sonia Sotomayor joined. Sotomayor also filed a concurring opinion, as did Justice Samuel Alito, in which Justices Ruth Bader Ginsburg, Stephen Breyer, and Elena Kagan joined. Read the opinion here.