See United States v. Marquez, 410 F.3d 612, 616 (9th Cir. 2005) ('Airport screenings of passengers and their baggage constitute administrative searches and are subject to the limitations of the Fourth Amendment.'). The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. U.S. Const. Amend. IV. This provision limits government action in two ways. First, it requires that searches and seizures be reasonable, and second, it states that when a warrant is required -- in circumstances not explicitly defined by the text -- it must have certain characteristics. See California v. Acevedo, 500 U.S. 565, 581, 111 S. Ct. 1982, 114 L. Ed. 2d 619 (1991) (Scalia, J., concurring).
The Supreme Court has read the Amendment's twin commands in tandem, holding that when people have a reasonable expectation of privacy in their persons or effects, all searches and seizures must be supported by a warrant, unless they fall into one of the ...