What is the standard for determining whether a witness committed perjury?

There are ambiguities in our case law regarding the proper standard to use, which could not have helped the district judge in sorting this out. The parties appear to agree that the two-part test from United States v. Wallach applies:

(1) Whether the perjury was material to the jury's verdict;

(2) The extent to which the prosecution knew or should have known about the

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perjury; ¹⁷

[653 F.3d 83]

(i) the witness actually committed perjury ; ¹⁹

(ii) the alleged perjury was material;

(iii) the government knew or should have known of the alleged perjury at the time of trial; and

(iv) the perjured testimony remained undisclosed during trial.

208 F.3d 72, 102 (2d Cir.2000) (internal quotation marks omitted). Later cases add to the confusion by applying Wallach without referencing Zichettello. See, e.g., United States v. Stewart, 433 F.3d 273, 297 (2d Cir.2006). The tests are not necessarily incompatible, however.²⁰

(iii) the government knew or should have known of the alleged perjury at the time of trial; and

(iv) the perjured testimony remained undisclosed during trial.