United States v. Ramsey, 431 U.S. 606 (1977), was a United States Supreme Court case in which the Court held the search of letters or envelopes from foreign countries falls under the border exception to the Fourth Amendment to the United States Constitution, which prohibits unreasonable searches and seizures.

[1] United States customs agents, investigating a "mail-order" drug business, opened eight envelopes from Thailand.

"[3] The government used the evidence it obtained from opening the letters when charging Charles W. Ramsay and James W. Kelly with violating federal laws related to drug trafficking.

[1][4] Ramsay and Kelly argued that the evidence was inadmissible, as the result of an illegal search.

[2] In a six to three decision, the Supreme Court ruled 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," declaring the warrantless search of the envelopes to be legal and the evidence to be admissible.