Giglio v. United States

In Brady v. Maryland, the Supreme Court held the suppression of material evidence justifies a new trial notwithstanding the good or bad faith of the prosecution. When the reliability of a given witness may determine guilt or innocence, nondisclosure of evidence affecting credibility falls within this general rule. The Court does not, however, automatically require a new trial whenever a combing of the prosecutors’ files after the trial has disclosed evidence possibly useful to the defense, but not likely to have changed the verdict. A finding of materiality of the evidence is required under Brady. A new trial is required if the false testimony could in any reasonable likelihood have affected the judgment of the jury.