## Facts

- In 1950, Walder was indicted in federal court for purchasing and possessing heroin; the heroin was seized during an unlawful search.
- The trial court granted Walder’s suppression motion, and the government dismissed that case.
- In 1952, Walder was indicted for four different narcotics transactions; the government’s proof relied mainly on testimony from two addicts acting under federal agents’ direction.
- Walder testified as the sole defense witness and denied the charged dealings.
- On direct examination, Walder made broad denials that he had ever purchased, sold, or possessed narcotics.
- Over objection, the government cross-examined Walder about the previously seized heroin capsule; he denied any narcotics were taken from him in 1950.
- The government then presented testimony from an officer involved in the unlawful search and a chemist who analyzed the capsule.
- The trial court admitted this evidence solely to impeach Walder’s credibility and instructed the jury it could not be used as proof of the charged crimes.
- Walder was convicted; the court of appeals affirmed.

## Issues

1. Whether the prosecution may use evidence previously suppressed as the product of an unlawful search solely to impeach a defendant’s credibility after the defendant voluntarily offers sweeping testimony denying any narcotics involvement.

## Decision

- The Supreme Court affirmed.
- A defendant’s broad claim that he has never possessed narcotics “opens the door” to contradiction by otherwise inadmissible evidence, when offered only to impeach credibility.
- The exclusionary rule bars affirmative use of illegally obtained evidence to prove guilt, but does not bar its limited use to challenge a defendant’s untruthful, sweeping testimony.
- The limiting instruction restricting the evidence to impeachment supported admissibility for that narrow purpose.

## Legal Principles

- Illegally obtained evidence remains inadmissible in the prosecution’s case-in-chief to establish guilt.
- The exclusionary rule does not permit a defendant to use prior suppression as a shield against contradiction when the defendant voluntarily testifies falsely in broad terms.
- When a defendant makes sweeping assertions, the government may introduce otherwise excluded evidence to impeach credibility, provided it is confined to that purpose and not treated as substantive proof of guilt.

## Conclusion

The Court held that the government may use evidence previously suppressed due to an unlawful search to impeach a defendant who voluntarily offers sweeping, false testimony, so long as the evidence is limited to credibility and not used to prove the charged offenses.


Walder v. United States, 347 U.S. 62 (1954)