A huge win at the Supreme Court today. In a much awaited case, the Supreme Court held 9 to 0 that if the government installs a GPS tracking device on your car, and monitors the movements of your car for a significant period of time, without a warrant, it violates the Fourth Amendment.

Welcome to the 21st century! Government searches are more invasive and insidious than they were when the constitution was written. As Justice Alito wryly commented in his concurring opinion, it would have required a very large coach, and a very tiny constable, in order for authorities to have approximated the level of surveillance attained in this case back then.

The Supreme Court unanimously held in United States v. Antoine Jones today that “the Government’s installation of a GPS device on a target’s vehicle, and its use of that device to monitor the vehicle’s movements” is a search under the Fourth Amendment. Antoine Jones was a nightclub owner suspected of drug dealing. Agents of the FBI climbed underneath his vehicle and installed a GPS tracking device in his Jeep Cherokee in order to monitor its every movement over a one month period of time. Because the government did not obtain a valid warrant, the court threw out the search.

The Majority opinion was written by Justice Scalia. It was joined by Justices Roberts, Kennedy, Thomas, and Sotomayor, who also wrote a Concurring opinion. The five-justice Majority concluded that the warrantless GPS monitoring of the defendant’s car violated the Fourth Amendment because the GPS technology was installed by means of an intrusion onto the defendant’s property, his car. It left for another day whether GPS tracking that does not require tinkering with the defendant’s car would violate the Fourth Amendment because of its sweeping invasion of individual privacy.

The decision today was deliberately narrow. The court decided the issue at hand, and left for the future whether or not a new technology that can track the movement of a vehicle without actually being physically attached would pass muster under the Fourth Amendment. The analyses of the justices is encouraging, though. At least five judges subscribed to the view that the Fourth Amendment is implicated by government intrusion onto private property OR the government’s violation of one’s reasonable expectation of privacy.