United States v. Jacobsen

In United States v. Jacobsen, 466 U.S. 109, 122 (1984), upheld a search of a package of cocaine first by a private carrier and then by federal agents after it spilled open during shipment:

"the concept of an interest in privacy that society is prepared to recognize as reasonable is, by its very nature, critically different from the mere expectation, however well justified, that certain facts will not come to the attention of authorities."