Napue v. Illinois

Key witness George Hamer, already convicted of the same policeman's murder Henry Napue (defendant) was tried for, testified against Napue and twice denied under oath that the state had promised him anything in exchange for his testimony, though he mentioned the public defender had promised to try to help him; in fact, the prosecutor had privately promised to recommend a reduced sentence for Hamer in exchange for his testimony, and the prosecutor never corrected Hamer's false denials at trial. Napue was convicted largely on Hamer's testimony and appealed, arguing the prosecutor's failure to correct testimony he knew was false violated his Fourteenth Amendment due process rights.