565 U.S. 400 (2012)
United States v. Jones marks a pivotal moment in Fourth Amendment jurisprudence at the intersection of property rights and digital surveillance.
Does the government conduct a Fourth Amendment "search" when it physically attaches a GPS tracking device to a suspect's vehicle and uses that device to monitor the vehicle's movements on public roads?
A government action constitutes a Fourth Amendment search when officers physically intrude on a constitutionally protected area—persons, houses, papers, or effects—with the purpose of obtaining information. The Katz reasonable-expectation-of-privacy test remains a separate and sufficient path to finding a search, but Katz does not displace the traditional, property-based trespass inquiry.
Yes. The government's physical attachment of a GPS device to Jones's vehicle, an "effect," and its use of that device to obtain information constituted a search under the Fourth Amendment. Because the government did not obtain a valid warrant and did not preserve an alternative basis for reasonableness, the judgment suppressing the GPS evidence was affirmed.
Jones re-centered property concepts in Fourth Amendment analysis while preserving Katz, giving courts two independent routes to deem government conduct a search: physical trespass on protected areas or violation of a reasonable expectation of privacy. Practically, Jones pushed law enforcement toward obtaining warrants for GPS tracking and laid doctrinal groundwork for subsequent digital-privacy decisions. Its concurring opinions anticipated the Court's recognition, in Carpenter v. United States, that long-term aggregation of location data (even without physical trespass) implicates reasonable expectations of privacy. For students, Jones illustrates how constitutional doctrine adapts to technology, how multiple opinions shape controlling principles, and how precedent (Knotts and Karo) is reconciled with modern surveillance capabilities.