Sorry just ripped this from Lexis-Nexis, seemed on point, discuss:
Government's interest in preventing the entry of unwanted persons and effects is at its zenith at the international border. Time and again, we have stated that "searches made at the border, pursuant to the longstanding right of the sovereign to protect itself by stopping and examining persons and property crossing into this country, are reasonable simply by virtue of the fact that they occur at the border." United States v. Ramsey, 431 U.S. 606, 616, 52 L. Ed. 2d 617, 97 S. Ct. 1972 (1977). HN3 Congress, [***8] since the beginning of our Government, "has 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." United States v. Montoya de Hernandez, 473 U.S. 531, 537, 87 L. Ed. 2d 381, 105 S. Ct. 3304 (citing Ramsey, supra, at 616-617, 52 L. Ed. 2d 617, 97 S. Ct. 1972 (citing Act of July 31, 1789, ch 5, 1 Stat 29)). The modern statute that authorized the search in this case, 46 Stat 747, 19 U.S.C. § 1581(a)[19 USCS § 1581(a)], n1 derived from a [**317] statute passed [*1586] by the First Congress, the Act of Aug. 4, 1790, ch 35, § 31, 1 Stat 164, see United States v. Villamonte-Marquez, 462 U.S. 579, 584, 77 L. Ed. 2d 22, 103 S. Ct. 2573 (1983), and reflects the "impressive historical pedigree" of the Government's power and interest, id., at 585, 77 L. Ed. 2d 22, 103 S. Ct. 2573. HN4 It is axiomatic that the United States, as sovereign, has the inherent authority to protect, and a paramount interest in protecting, its territorial integrity.
United States v. Flores-Montano, 124 S. Ct. 1582, 1585-1586 (U.S., 2004)
