## Facts

- Truong Dinh Hung cultivated a channel to pass classified U.S. information to officials of the Socialist Republic of Vietnam.
- Ronald Louis Humphrey, a U.S. Information Agency employee, provided Truong with classified documents about U.S. activities in Southeast Asia.
- Truong arranged for Dung Krall to deliver materials to Vietnamese officials in Paris; Krall acted as a confidential informant and allowed U.S. authorities to inspect the packages.
- Federal investigators conducted warrantless electronic surveillance, including a telephone tap and an apartment bug, for more than 250 days without judicial authorization.
- The Department of Justice began assembling a criminal prosecution on July 20, 1977; the district court treated that date as the point when the investigation’s primary purpose shifted from foreign intelligence to criminal prosecution.
- The district court admitted evidence obtained by warrantless surveillance before July 20, 1977, and suppressed evidence obtained after that date.
- Truong and Humphrey were arrested on January 31, 1978 and convicted in the Eastern District of Virginia of espionage, conspiracy to commit espionage, acting as agents of a foreign government, and related offenses.

## Issues

1. Whether warrantless electronic surveillance directed at suspected foreign espionage violates the Fourth Amendment, or is permissible under a foreign-intelligence exception when the surveillance’s primary purpose is foreign intelligence collection.
2. Whether the espionage statutes were constitutionally and properly applied to the transmission of classified national defense information to a foreign government.
3. Whether the federal theft-of-government-property statute applied to the charged conduct and, if so, whether any error required relief.
4. Whether the government violated the Jencks Act or denied defendants compulsory process through nonproduction of materials or evidentiary rulings.

## Decision

- The Fourth Circuit affirmed the espionage-related convictions and rejected most challenges to the trial court’s evidentiary rulings and compulsory process claims.
- The court recognized a foreign-intelligence exception to the warrant requirement and held that warrantless surveillance is permissible so long as its primary purpose is foreign intelligence gathering.
- The court upheld the district court’s cutoff date, admitting pre–July 20, 1977 surveillance evidence and sustaining suppression of post–July 20, 1977 evidence because the investigation had become primarily criminal.
- The court declined to decide the theft-of-government-property question under the concurrent sentence doctrine (though one judge stated he would reverse those convictions).
- The court remanded for limited proceedings to determine whether certain materials were producible under the Jencks Act and whether any nondisclosure prejudiced the defense.

## Legal Principles

- Warrantless electronic surveillance may be consistent with the Fourth Amendment when conducted for foreign intelligence purposes and when foreign intelligence collection is the surveillance’s primary purpose.
- When the primary purpose of an investigation shifts from foreign intelligence collection to criminal prosecution, continued electronic surveillance generally requires compliance with ordinary warrant procedures; evidence obtained without a warrant after the shift may be suppressed.
- Espionage statutes may reach a broad range of national defense information and apply to transmitting classified materials to a foreign government.
- Under the concurrent sentence doctrine, an appellate court may decline to resolve additional counts where vacating them would not affect the overall sentence.
- Potential Jencks Act violations require focused inquiry into whether withheld materials qualify as witness statements and whether any failure to produce caused prejudice.

## Conclusion

The court upheld the convictions largely because the warrantless surveillance was conducted for foreign intelligence purposes until the investigation became primarily prosecutorial, at which point later surveillance evidence was suppressed; the court otherwise affirmed and remanded only to address possible Jencks Act nondisclosure and prejudice.


United States v. Truong Dinh Hung, 629 F.2d 908 (4th Cir. 1980)