What evidentiary showing is required, under Napue v. Illinois, 360 U.S. 264 (1959), to establish that a prosecution witness has offered false testimony?

QUESTION PRESENTED At a criminal trial, Petitioner sought to confront a Government witness with notes of an interview, taken by Government agents, which reflected a prior inconsistent statement concerning an issue of central importance. The Government’s witness denied making the inconsistent statement recorded within the Government’s notes. Prosecutors did not seek to correct their witness’s testimony. To the contrary, in rebuttal summation, prosecutors embraced their witness’s testimony, arguing that their own notes of the interview should not be credited as an accurate record of his prior statement. On Appeal, Petitioner argued that prosecutors were obligated to correct their witness where they knew or should have known that he had, in fact, made a prior inconsistent statement. Petitioner further argued that the prosecutor’s conduct in endorsing such perjury constituted a clear-cut violation of this Court’s holding in Napue v. Illinois, 360 U.S. 264, 269 (1959). The Second Circuit Court of Appeals affirmed Petitioner’s conviction, holding that the Government’s notes of the witness’s interview were “not incontrovertible evidence” of the witness’s earlier statements, and that as a result, Petitioner could not establish that the witness “committed perjury, let alone that the Government knew or should have known that he did so.” ii A prosecutor’s obligation to correct perjurious testimony, offered by a government witness, is well established. However, this Court’s precedent is silent as to the quantum of proof necessary to establish such perjury. In the absence of such guidance, different courts have adopted disparate and varying standards. Here, the Second Circuit Court of Appeals held that Petitioner was obligated to offer “incontrovertible evidence” of such perjury. Accordingly, this Petition presents the following question: 1. What evidentiary showing is required, under Napue v. Illinois, 360 U.S. 264 (1959), to establish that a prosecution witness has offered false testimony? ili