In summary, we hold that stops for brief questioning routinely conducted at permanent checkpoints are consistent with the Fourth Amendment, and need not be authorized by warrant. [Footnote 19] The principal protection of Fourth
Page 428 U. S. 567
Amendment rights at checkpoints lies in appropriate limitations on the scope of the stop. See Terry v. Ohio, 392 U.S. at 392 U. S. 24-27; United States v. Brignoni-Ponce, 422 U.S. at 422 U. S. 881-882. We have held that checkpoint searches are constitutional only if justified by consent or probable cause to search. United States v. Ortiz, 422 U. S. 891 (1975). And our holding today is limited to the type of stops described in this opinion. "[A]ny further detention . . . must be based on consent or probable cause." United States v. Brignoni-Ponce, supra at 422 U. S. 882.None of the defendants in these cases argues that the stopping officers exceeded these limitations.

Hope that clears things up for you.