What is the test for obtaining a search warrant to search a person's baggage at a border crossing?

While a border search may be initiated in the absence of both a warrant and probable cause, the officer conducting the search must nonetheless proceed in a reasonable manner. See United States v. Guadalupe-Garza, 421 F.2d 876, 878 (9th Cir.1970). Thus, while every person crossing the border may be required to disclose the contents of his or her baggage based on nothing more than the fact that he has crossed the border, more intrusive searches must be supported by some level of suspicion. Id.; Henderson v. United States, 390 F.2d 805, 808 (9th Cir.1967).