## Facts

- Federal agents investigated narcotics trafficking and suspected Roy Mandujano of involvement in an attempted heroin sale negotiated with an undercover agent.
- Mandujano was subpoenaed to testify before a federal grand jury about the suspected drug activity.
- Before testifying, the prosecutor advised Mandujano that he could refuse to answer incriminating questions, that other questions had to be answered truthfully on pain of perjury, and that he could consult a lawyer outside the grand jury room.
- Mandujano was not given full Miranda warnings.
- During grand jury testimony, Mandujano made statements later alleged to be knowingly false concerning his involvement in the attempted heroin transaction.
- Mandujano was charged with attempted distribution of heroin and with perjury based on the grand jury testimony; the perjury charge depended on the grand jury statements.

## Issues

1. Whether a subpoenaed grand jury witness who may have been involved in the criminal conduct under investigation must receive full Miranda warnings.
2. Whether the absence of full Miranda warnings requires suppression of false grand jury testimony in a subsequent perjury prosecution based on that testimony.

## Decision

- The Supreme Court reversed the suppression order and remanded.
- The Court held that full Miranda warnings are not constitutionally required for questioning of a witness appearing before a grand jury pursuant to subpoena.
- The Court held that a witness’s false statements to a grand jury are not suppressible on Miranda grounds in a later prosecution for perjury based on those statements.
- No single majority opinion controlled the reasoning; a plurality and separate concurrences agreed on the judgment.
- Justice Stevens did not participate.

## Legal Principles

- Miranda applies to custodial interrogation; grand jury questioning of a subpoenaed witness is not treated as custodial interrogation requiring Miranda warnings.
- The Fifth Amendment privilege against self-incrimination permits a witness to decline to answer incriminating questions, but it does not confer a right to provide false answers.
- A perjury prosecution may proceed even when a witness faced potential self-incrimination, because the proper course is to invoke the privilege rather than lie.
- Due process does not bar a perjury prosecution absent coercive or fundamentally unfair governmental conduct inducing the false testimony.

## Conclusion

The Court permitted Mandujano’s perjury prosecution to go forward, ruling that grand jury witnesses are not entitled to full Miranda warnings and that lack of such warnings does not justify suppressing false grand jury testimony when it is used to prosecute perjury.


United States v. Mandujano, 425 U.S. 564 (1976)