United States v. Truong Dinh Hung

Truong Dinh Hung (defendant), a Vietnamese political activist, used a source he believed was a sympathetic courier, Dung Krall, to pass classified U.S. documents obtained from USIA employee Ronald Humphrey (defendant) to Vietnamese representatives in Paris. Unbeknownst to Truong, Krall was a CIA/FBI informant who handed the packages over for inspection before delivering them, for over a year. Once Truong's activity was discovered, the government wiretapped his phone and bugged his apartment without any warrant for over 250 days. The Justice Department began building a criminal case on July 20, 1977; Truong and Humphrey were arrested the following January. The district court excluded surveillance evidence gathered after July 20 (when the criminal investigation began) but admitted everything gathered before that date; both men were convicted and appealed, arguing the entire surveillance violated the Fourth Amendment.