The Government obtained a search warrant permitting it to install a Global-Positioning-System (GPS) tracking device on a vehicle registered to respondent Jones's wife. The warrant authorized installation in the District of Columbia and within 10 days, but agents installed the device on the 11th day and in Maryland. The Government then tracked the vehicle's movements for 28 days. It subsequently secured an indictment of Jones and others on drug trafficking conspiracy charges. The District Court suppressed the GPS data obtained while the vehicle was parked at Jones's residence, but held the remaining data admissible because Jones had no reasonable expectation of privacy when the vehicle was on public streets. Jones was convicted. The D. C. Circuit reversed, concluding that admission of the evidence obtained by warrantless use of the GPS device violated the Fourth Amendment. Held: The Government's attachment of the GPS device to the vehicle, and its use of that device to monitor the vehicle's movements, constitutes a search under the Fourth Amendment. Pp. 3-12. (a) The Fourth Amendment protects the "right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures." Here, the Government's physical intrusion on an "effect" for the purpose of obtaining information constitutes a "search." This type of encroachment on an area enumerated in the Amendment would have been considered a search within the meaning of the Amendment at the time it was adopted. Pp. 3-4. (b) This conclusion is consistent with this Court's Fourth Amendment jurisprudence, which until the latter half of the 20th century was tied to common-law trespa**. Later cases, which have deviated from that exclusively property-based approach, have applied the an*lysis of Justice Harlan's concurrence in Katz v. United States, 389 U. S. 347, which said that the Fourth Amendment protects a person's "reasonable expectation of privacy," id., at 360. Here, the Court need not address the Government's contention that Jones had no "reasonable expectation of privacy," because Jones's Fourth Amendment rights do not rise or fall with the Katz formulation. At bottom, the Court must "a**ur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted." Kyllo v. United States, 533 U. S. 27, 34. Katz did not repudiate the understanding that the Fourth Amendment embodies a particular concern for government trespa** upon the areas it enumerates. The Katz reasonable-expectation-of-privacy test has been added to, but not substituted for, the common-law trespa**ory test. See Alderman v. United States, 394 U. S. 165, 176; Soldal v. Cook County, 506 U. S. 56, 64. United States v. Knotts, 460 U. S. 276, and United States v. Karo, 468 U. S. 705--post-Katz cases rejecting Fourth Amendment challenges to "beepers," electronic tracking devices representing another form of electronic monitoring--do not foreclose the conclusion that a search occurred here. New York v. Cla**, 475 U. S. 106, and Oliver v. United States, 466 U. S. 170, also do not support the Government's position. Pp. 4-12. (c) The Government's alternative argument--that if the attachment and use of the device was a search, it was a reasonable one--is forfeited because it was not raised below. P. 12. 615 F. 3d 544, affirmed. Scalia, J., delivered the opinion of the Court, in which Roberts, C. J., and Kennedy, Thomas, and Sotomayor, JJ., joined. Sotomayor, J., filed a concurring opinion. Alito, J., filed an opinion concurring in the judgment, in which Ginsburg, Breyer, and Kagan, JJ., joined.