Napue v. Illinois

Background

A man was tried for murder largely on the testimony of a fellow defendant who was already serving a 199-year sentence. That witness told the jury no one had promised him any help for testifying, but the prosecutor had in fact promised consideration and did not correct the false statement. The jury was told only that a public defender had said he would “do what he could.” The defendant was convicted and sentenced to 199 years.

Reasoning

The Court addressed whether the prosecutor’s failure to correct testimony he knew to be false denied the defendant fair process under the Fourteenth Amendment. The Court said that using or allowing known false evidence cannot stand in a fair trial. It emphasized that lies about a witness’s motive or promises affect credibility and can change a jury’s decision. The Court reviewed the record itself, rejected the state court’s view that the jury’s vague notice about a public defender cured the defect, and concluded the false testimony might have affected the outcome.

Real world impact

The ruling requires prosecutors to correct known lies by witnesses and makes convictions vulnerable when important testimony was knowingly left false. It also affirms that the Supreme Court will independently examine records where federal constitutional rights are claimed. The decision protects defendants when a witness’s credibility is tainted by undisclosed promises.

Dissents or concurrances

A dissenting view in the state court had argued the jury already knew some possibility of help for the witness, but the Supreme Court found that was insufficient to ensure a fair trial.