"The Government's interest in preventing the entry of unwanted persons and effects is at its zenith at the international border." In light of the Government's interest in protecting its sovereignty and territorial integrity, "searches made at the border... are reasonable simply by virtue of the fact that they occur at the border." Indeed, the statute authorizing the search in this case derived ultimately from a statute first passed in 1789.
"The Government's interest in safeguarding its sovereignty and territorial boundaries reaches its highest point at the international border." Consequently, "searches conducted at the border... are deemed acceptable merely because they occur at the border."