Giglio v. United States

In Giglio, the Court held that the prosecution's failure to inform the jury that a witness had been promised not to be prosecuted in exchange for his testimony was a failure to fulfill the duty to present all material evidence to the jury, and constituted a violation of due process, requiring a new trial. This is the case even if the failure to disclose was a matter of negligence and not intent. The case extended the Court's holding in Brady v. Maryland, requiring such agreements to be disclosed to defense counsel. As a result of this case, the term Giglio material is sometimes used to refer to any information pertaining to deals that witnesses in a criminal case may have entered into with the government.