GPS Monitoring Device Leads the Supreme Court to the Crossroads in Privacy Law

The case of United States v. Jones led the United States Supreme Court to a crossroads in its Fourth Amendment jurisprudence. The Jones Court had to decide whether law enforcement’s use of a GPS device to monitor a suspect’s vehicle around the clock for a month constituted a “search” within the meaning of the Fourth Amendment. The case presented a potential collision between two different approaches to identifying Fourth Amendment searches.The first is a “location-driven” approach in which government intrusions into private locations constitute Fourth Amendment searches, while government observations from outside private locations do not. In Katz v. United States, the Court rejected a strictly “location-driven” approach and instead reasoned that the Fourth Amendment protects “people, not places.” Although the Court has nominally applied the Katz “reasonable expectations” test for the last four decades, the Court’s post-Katz surveillance cases have largely returned to the location-driven approach.Had the Court continued this location-driven approach, it would have held that GPS monitoring in public spaces was not a Fourth Amendment search, on the theory that people have no expectation of privacy while in a public space. However, one can read the Court’s post-Katz decisions to support a second approach, a “situation-based” approach, that is better suited to deal with changing technologies and is more faithful to the “reasonable expectations” test that the Court purports to apply. In a fractured decision, a majority in Jones adopted the situation-based approach and held that the government’s long-term use of GPS monitoring violated the defendant’s reasonable expectation of privacy in his movements over time along public roads.