This morning, the Supreme Court handed down its decision in United States v. Jones, the GPS tracking case, deciding unanimously that the government violated the defendant’s Fourth Amendment rights when it installed a wireless GPS tracking device on the undercarriage of his car and used it to monitor his movement’s around town for four weeks without a search warrant.
Despite the unanimous result, the court was not unified in its reasoning. Five Justices signed the majority opinion, authored by Justice Scalia, finding that the Fourth Amendment “at bottom . . . assure[s] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted” and thus analyzing the case under “common-law trespassory” principles.
Justice Alito wrote a concurring opinion, signed by Justices Ginsburg, Breyer, and Kagan, faulting the majority for “decid[ing] the case based on 18th-century tort law” and arguing instead that the case should be decided under Katz’s “reasonable expectations of privacy” test. Applying Katz, the four concurring Justices would have found that the government violated the Fourth Amendment because “long-term tracking” implicated a reasonable expectation of privacy and thus required a warrant.
Justice Sotomayor, who signed the majority opinion, wrote a separate concurring opinion, but more on that in a second.