Giglio v. United States

Petitioner was convicted of passing forged money orders and sentenced to five years’ imprisonment. While appeal was pending in the Court of Appeals, defense counsel discovered new evidence indicating that the Government had failed to disclose an alleged promise made to its key-witness that he would not be prosecuted if he testified for the Government. We granted certiorari to determine whether the evidence not disclosed was such as to require a new trial under the due process criteria of Napue v. Illinois, 360 U. S. 264 (1959), and Brady v. Maryland, 373 U. S. 83 (1963).

The controversy in…