## Facts

- A robbery and shooting occurred in a Chicago cocktail lounge in 1938, killing an off-duty police officer; Henry Napue was later prosecuted for the officer’s murder.
- A participant, George Hamer, pleaded guilty and received a 199-year sentence; he later became the State’s principal witness against Napue.
- At Napue’s trial, Hamer testified on direct examination that he had received no promise of consideration in exchange for his testimony regarding a reduction of his sentence.
- The prosecutor had in fact promised Hamer favorable consideration and later sought to reduce Hamer’s sentence, stating that a recommendation for reduction had been promised if Hamer testified.
- The prosecutor did not correct Hamer’s false denial at trial.
- The jury heard some information suggesting Hamer hoped for help from a public defender, but it was not told that the prosecutor had made a specific promise.
- Napue was convicted and sentenced to 199 years, with the case against him resting largely on Hamer’s testimony.

## Issues

1. Whether due process is denied when the prosecution fails to correct testimony it knows to be false, even when the falsehood concerns a witness’s credibility (a promise of leniency).
2. What standard governs whether such known false testimony requires relief.

## Decision

- The Supreme Court unanimously reversed the Illinois Supreme Court’s judgment affirming denial of post-conviction relief.
- The Court held that the prosecutor’s failure to correct testimony known to be false violated the Fourteenth Amendment’s Due Process Clause.
- The Court rejected the argument that other impeachment evidence cured the constitutional violation.
- The Court independently reviewed the record relevant to the federal constitutional claim rather than deferring to the state court’s factual conclusion.

## Legal Principles

- The State may not knowingly use false testimony to obtain a conviction, and the same rule applies when the prosecutor knowingly allows false testimony to stand uncorrected.
- This duty applies even when the false testimony relates only to witness credibility, including undisclosed promises or expectations of leniency.
- Relief is required when the false testimony may have affected the outcome of the trial; the defendant need not show it definitively changed the verdict.
- Evidence of other reasons to doubt a witness’s motives does not necessarily eliminate the prejudice from a prosecutor’s suppression or non-correction of a distinct promise of consideration.

## Conclusion

A conviction obtained after the prosecution knowingly leaves uncorrected false testimony about a key witness’s promised benefit violates due process, because the jury is entitled to accurate information bearing on credibility and such falsehoods may affect the verdict.


Napue v. Illinois, 360 U.S. 264 (1959)