At the international border in southern California, customs officials seized 37 kilograms of marijuana from respondent's gas tank by removing and disassembling the tank. After respondent was indicted on federal drug charges, he moved to suppress the drugs recovered from the gas tank, relying on a Ninth Circuit panel decision holding that a gas tank's removal requires reasonable suspicion under the Fourth Amendment. The District Court granted the motion, and the Ninth Circuit summarily affirmed.

Held: The search did not require reasonable suspicion. In the decision relied on below, the Ninth Circuit panel seized on language from United States v. Montoya de Hernandez, 473 U. S. 531, 538, that used "routine" as a descriptive term in discussing border searches. The panel took "routine," fashioned a new balancing test, and extended it to vehicle searches. But the reasons that might support a suspicion requirement in the case of highly intrusive searches of persons simply do not carry over to vehicles. Complex balancing tests to determine what is a "routine" vehicle search, as opposed to a more "intrusive" search of a person, have no place in border searches of vehicles. The Government's interest in preventing the entry of unwanted persons and effects is at its zenith at the international border. United States v. Ramsey, 431 U. S. 606, 616. Congress has always granted the Executive plenary authority to conduct routine searches and seizures at the border, without probable cause or a warrant, in order to regulate the collection of duties and to prevent the introduction of contraband into this country. Montoya de Hernandez, supra, at 537. Respondent's assertion that he has a privacy interest in his fuel tank, and that the suspicionless disassembly of his tank is an invasion of his privacy, is rejected, as the privacy expectation is less at the border than it is in the interior, id., at 538, and this Court has long recognized that automobiles seeking entry into this country may be searched, see Carroll v. United States, 267 U. S. 132, 154. And while the Fourth Amendment "protects property as well as privacy," Soldal v. Cook County, 506 U. S. 56, 62, the interference with a motorist's possessory interest in his gas tank is justified by the Government's paramount interest in protecting the border. Thus, the Government's authority to conduct suspicionless inspections at the border includes the authority to remove, disassemble, and reassemble a vehicle's fuel tank. Pp. 2-7.

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