The Supreme Court has unanimously ruled that GPS tracking of a suspect’s car for an extended period of time without a warrant violates the Fourth Amendment (PDF opinion). The District Court had ruled that data about the car when it was at the suspect’s private residence was a inadmissible because the police did not have a warrant, but information about the suspect’s driving on public roads was admissible because he had no reasonable expectation of privacy there. Writing for the majority, Justice Scalia stressed how the government physically intruded on one of the suspect’s “effects” and used that effect to secretly monitor the suspect. The Court held that it was not necessary to apply the “reasonable expectation of privacy” test from Katz v. United States, 389 U. S. 347 (1967) because this test applies in addition to (and does not supplant) the traditional property-based approach used in Fourth Amendment analysis. The opinion explains, “for most of our history the Fourth Amendment was understood to embody a particular concern for government trespass upon the areas (‘persons, houses, papers, and effects’) it enumerates. Katz did not repudiate that understanding.”
Justice Sotomayor joined in the opinion, and wrote separately to discuss the unique attributes of GPS monitoring and how police monitoring of civilians may affect our democratic society.
Justice Alito concurred in judgment and wrote a separate opinion arguing that the case should be decided based on the more modern “reasonable expectations of privacy” test. This concurring opinion argued that short-term monitoring of a suspect’s vehicle would not violate such expectations, but long term monitoring would violate them. It explained, “In this case, for four weeks, law enforcement agents tracked every movement that respondent made in the vehicle he was driving. We need not identify with precision the point at which the tracking of this vehicle became a search, for the line was surely crossed before the 4-week mark.”
Each approach certainly leaves much of the law undecided. Under the minority view, it is unclear at what point the line would be “crossed” and police monitoring of a suspect’s car would constitute a “search.” Under the majority view, which is now binding precedent, it is unclear what the result would be if the police were able to track a car via GPS without physically intruding on the vehicle.
Image: CC BY-NC 2.0 / S.E.B.