What is the current state of the law governing the inspection of travellers crossing our national boundaries?

Of necessity, the law governing the inspection of travellers crossing our national boundaries is responsive to a different set of imperatives from those that guide law enforcement officers in their investigative contacts with persons who already are within this country. It long has been established that routine border searches, conducted for the purpose of controlling the movement of people and goods across our national boundaries, do not violate the Fourth Amendment's prohibition against unreasonable searches. See United States v. Asbury, 586 F.2d 973, 976 (2d Cir. 1978) and cases cited therein.