Impeachment Evidence: Attacking Credibility And Proving Its Truth?  

Feb 23, 2019

When it comes to impeachment—attacking the credibility of a witness—lawyers sometimes fail to consider whether the evidence is substantive or pure impeachment. It can lead to an exchange like the following:

Judge: Are you offering this evidence as pure impeachment or to establish its truth?

Lawyer: Yes.

Knowing whether impeachment evidence may also be substantive is important. Substantive evidence “is offered to establish the truth of a matter to be determined by the trier of fact.” Chiasson v. Zapata Gulf Marine Corp., F. 2d 513, 517 (5th Cir. 1993). Impeachment evidence, meanwhile, is “offered to discredit a witness [and] reduce the effectiveness of her testimony by bringing forth evidence which explains why the jury should not put faith in her … testimony.” Id.

Impeachment by contradiction, for example, is evidence used “[t]o attack the credibility of witnesses by the presentation of evidence showing that facts asserted or relied upon in their testimony are false…” Wegener v. Johnson, 527 F. 3d 687, 691 (8th Cir. 2008). Separate and apart from whether the impeachment evidence contradicts a witness’ testimony, there are occasions where impeachment evidence also tends to establish the truth of a necessary fact or issue. Whether impeachment evidence provides some utility beyond impeachment can be a deciding factor in federal court cases when a party seeks to introduce “impeachment” evidence that was not otherwise provided in that party’s pretrial disclosures. See e.g., Stanley v. Edmonds-Leach, 783 F. 3d 1276, 1283 (D.C. Cir. 2015).


To be sure, whether impeachment evidence is also substantive during trial is often of little practical significance. Once a jury has heard or seen something, adhering to a judge’s limiting instruction is not terribly realistic. (Don’t believe me? Try to spend the next five minutes not thinking about giant kangaroos.) There are some occasions, however, where the distinction is significant.  

Inconsistent Statements as Impeachment and Substantive Evidence 

Consider, for example, a wrongful death case where the defendant’s car collided with the decedent. The issue in the case is whether the defendant ran a red light. The defendant claims the light was green. The decedent passed away immediately, but an eyewitness told an investigator in an interview (months before trial) that the defendant ran a red light. At trial, the same eyewitness takes the stand and testifies that the light was green. The plaintiff’s lawyer wishes to impeach the eyewitness with her prior inconsistent statement that the light was red. The plaintiff’s lawyer also wishes to introduce the prior inconsistent statement as substantive evidence that the defendant ran the red light. If the statement is only admitted as impeachment evidence, the plaintiff is without any substantive evidence that the defendant ran a red light, and could face a motion for judgement. 

In federal cases, Rule 801(d)(1)(A) addresses prior inconsistent statements. It provides that a statement is not hearsay (i.e., it is admissible to prove the truth of the matter asserted) so long as the inconsistent statement “was given under penalty of perjury at a trial, hearing, or other proceeding or in a deposition…” Because the prior inconsistent statement—to be admissible as substantive evidence—must have been under penalty of perjury, our eyewitness’ prior inconsistent statement from the above-hypothetical would not be admitted as substantive evidence. 

California’s Code of Evidence provides different result. Section 1235 provides that “[e]vidence of a statement made by a witness is not inadmissible by the hearsay rule if the statement is inconsistent with his testimony at the hearing and is offered in compliance with Section 770.” Unlike the Federal Rules of Evidence, Section 1235 does not require that the prior inconsistent statement have been made under oath; however, it must be offered “in compliance with Section 770[,]” which provides as follows:

Unless the interests of justice otherwise require, extrinsic evidence of a statement made by a witness that is inconsistent with any part of his testimony at the hearing shall be excluded unless:

(a) The witness was so examined while testifying as to give him an opportunity to explain or to deny the statement;  or

(b) The witness has not been excused from giving further testimony in the action.

Cal. Evid. Code § 770.

Returning to our wrongful death hypothetical, there are a couple ways the plaintiff could—in California state court—introduce the eyewitness’ prior inconsistent statement as substantive evidence. The plaintiff could introduce the prior statement through the eyewitness and allow the eyewitness to either explain or deny the prior statement. If the eyewitness denies making the statement, the plaintiff’s lawyer—both for reasons of persuasion and procedure—will want another witness introduce the statement so there is actual affirmative evidence that the eyewitness made the statement. The reason for this is that even if the eyewitness’ denial is not believable, an unreliable denial does not constitute affirmative evidence. “Disbelief does not create affirmative evidence to the contrary of that which is discarded. ‘The fact that a jury may disbelieve the testimony of a witness who testifies to the negative of an issue does not of itself furnish any evidence in support of the affirmative of that issue, and does not warrant a finding in the affirmative thereof unless there is other evidence in the case to support such affirmative.’” Estate of Bould, 135 Cal. App. 2d 260, 264 (1955), citing Marovich v. Central Calif. Traction Co., 191 Cal. 295, 304 (1923); see also Edmondson v. State Bar, 29 Cal. 3d 339 (1981) (“[T]he rejection of testimony ‘does not create affirmative evidence to the contrary of that which is discarded.’”).

Alternatively, after the eyewitness’ examination has concluded, the plaintiff’s lawyer can advise the court that eyewitness should not be excused from providing further testimony in the trial (e.g., “Pursuant to Section 770, the plaintiff requests that the court not excuse this witness from providing further testimony.”). So long as the eyewitness is not excused, the plaintiff’s lawyer is free to call its investigator who can then tell the jury what the eyewitness said months earlier.


The next time a trial judge asks whether some proposed evidence is impeachment or substantive, you now know the best response is not, “tomayto, tomahto!”  

David Sugden is a shareholder at Call & Jensen. He can be reached at [email protected].  


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