The U.S. Supreme Court just announced its decision in U.S. v. Jones, ruling unanimously that the government must obtain a warrant before affixing a GPS tracking device to a suspect’s vehicle. While all the justices agreed that the Fourth Amendment required police to obtain a warrant they did not agree on the rationale. Five joined Justice Scalia’s majority opinion that the Fourth Amendment applied to private property such as a vehicle. Four agreed with Justice Alito that this warrantless search violated the defendant’s reasonable expectation of privacy. According to the article just posted by The Wall Street Journal–
Justice Alito warned that a property-based approach was too narrow to guard against the proliferating threats to personal privacy modern technology posed. Justice Scalia stressed, however, that the majority wasn’t repudiating the broader test articulated in 1967, but rather that it was unnecessary to reach it because installation of the tracker was sufficient by itself to trigger the Fourth Amendment.