Typically, one doesn't need a videotape or countervailing testimony from an amalgam of the Pope, Abraham Lincoln and Tom Brokaw to know that a witness has lied. Sometimes a lie is simply unmistakable—”It's as plain,” a trial lawyer might tell a jury, “as the nose on my face.” Indeed, a false statement may be clear whether it occurs in the real world, or on the witness stand in the courtroom's pristine atmosphere. Often, one simply doesn't need an infallible lie detector, even if such a thing existed, to reach a conclusion about witness falsity.

The Rules

The consequences in the criminal courtroom regarding a proponent's offer of what is—or turns out to be—false testimony are somewhat different, however, depending on which side proffers the testimony. No lawyer can “knowingly” make or fail to correct “a false statement of material fact” and, if the lawyer learns that material evidence is false, he “shall take remedial measures, including, if necessary, disclosure to the tribunal.” But: “A lawyer may refuse to offer evidence, other than the testimony of a defendant in a criminal matter, that the lawyer reasonably believes is false.” NY Rule of Professional Conduct 3.3(a), ABA Model Rule of Professional Conduct 3.3(a). Yes, a defendant has the absolute right to testify even if his attorney doesn't believe his account, as long as the attorney doesn't actually “know” the testimony would be false. Meaning, an attorney must call his insistent client (but not a witness) to the stand notwithstanding his personal beliefs as to that testimony.

A prosecutor's burden is different. A “prosecutor … shall make timely disclosure … of evidence or information … that tends to negate the guilt of the accused, mitigate the degree of the offense, or reduce the sentence … ” NY Rule 3.8(b); ABA Rule 3.8(d). See ABA Rules for the Prosecution Function 3-3.11. We're not talking about Brady material, where criminal defendants have a due process right to receive favorable, material evidence. Brady v. Maryland, 373 U.S. 83 (1963). Look again at the language of Rule 3.8—a prosecutor must disclose if information tends to negate guilt. Meaning, the obligation goes “beyond the corollary duty imposed upon prosecutors by constitutional law.” ABA Formal Op. 09-454, at n 17 quoting commentary to 3-3.11.

A prosecutor's duty is not simply to win, but to assure that justice prevails. Berger v. U.S., 295 U.S. 78 (1935) (a prosecutor is a “minister of justice”).

Trial Testimony

So what if a prosecution witness lies? Not that the prosecutor suborned perjury, he just failed to correct the record. In Alcorta v. Texas, 355 U.S. 28 (1957), a defendant claimed he killed his wife in the heat of passion because of her infidelity. The lover testified for the prosecution at trial and claimed they were not having an affair, despite having earlier told the prosecutor the opposite. When the witness later gave a sworn statement that he lied at trial, and the prosecutor acknowledged the witness's pre-trial disclosure, the judgment was reversed on due process grounds.