Consider the following scenario: In a criminal trial for illegal possession of a firearm, a police officer testifies that she stopped the defendant on the street, frisked him, and found a gun in his pocket. The defense then produces video footage from a bystander that shows the officer actually retrieving the gun from underneath a nearby bush. The defendant is acquitted, but the prosecutor decides not to charge the officer with perjury.1

One year later, a different defendant is charged with assaulting a police officer—the same officer from the first case. The officer testifies that the defendant threw a rock at her. On cross-examination, the defense attorney asks the officer, “One year ago, didn’t you get away with lying on the stand in this very courtroom?” The officer denies it. Should the defense attorney be able to introduce a transcript of the officer’s prior testimony, as well as the contradictory video? Current understandings of the Federal Rules of Evidence (FRE)—specifically, FRE 608(b)—and similar state evidence codes would say no, because the officer was never convicted of perjury.

The FRE codify a permissive theory of evidence adapted from the common law of evidence. Relevant evidence is presumptively admissible, subject to exceptions in the Constitution, federal statutes, the FRE, or other rules created by the Supreme Court.2 The basic test for excluding evidence is embodied in FRE 403, which allows a trial court to exclude evidence “if its probative value is substantially outweighed” by certain dangers: “unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.”3 Other exclusionary rules in the FRE are derived from FRE 403, replacing the broad standard with a specific rule governing a particular circumstance.4

One such rule is FRE 404(b), which forbids introducing “[e]vidence of a crime, wrong, or other act . . . to prove a person’s character in order to show that on a particular occasion the person acted in accordance with the character.”5 It does allow evidence of prior acts to be admitted “for another purpose, such as proving motive, opportunity, intent, preparation, plan, knowledge, identity, absence of mistake, or lack of accident.”6 FRE 608(b), in turn, allows “specific instances of a witness’s conduct” to be “inquired into [on cross-examination] if they are probative of the character for truthfulness or untruthfulness of” either “the witness” or “another witness whose character the witness being cross-examined has testified about.”7

FRE 608(b) also codifies a long-standing common-law rule of evidence, known as the extrinsic evidence bar. While the witness may be asked on cross-examination about prior acts relevant to his character for truthfulness, the cross-examining party may not introduce extrinsic evidence of those acts,8 unless the acts resulted in a criminal conviction.9 Thus, in the hypothetical above, the defense attorney would not be able to contradict the officer’s denial with the video and prior testimony because both pieces of evidence would be extrinsic to the officer’s testimony on the stand.

Prior acts may be proven by extrinsic evidence when they relate to other forms of impeachment, including bias and interest.10 Together, bias and interest make up the category of motive to lie (or slant or distort one’s testimony).11 Courts are divided over whether impeachment is “another purpose,” albeit an unlisted one, for which extrinsic evidence is admissible under FRE 404(b)(2), or whether FRE 404(b) does not apply to impeachment evidence at all.12 Either way, courts admit evidence of other acts when they are relevant to bias.13

A recently resurrected theory of impeachment would allow the defense attorney to introduce the video and prior testimony in the opening hypothetical. In the last few years, the DC Court of Appeals14 has issued several opinions developing a theory of impeachment called “corruption bias.” This type of impeachment involves demonstrating that a witness is willing to obstruct the discovery of truth by manufacturing or suppressing testimony. Proof of such willingness typically takes the form of prior instances of uncharged perjury. According to the DC Court of Appeals, corruption bias, as a subset of bias, is distinct from evidence of a bad character for truthfulness. Corruption bias evidence is therefore not subject to the DC Court of Appeals’ version of the FRE 608(b) extrinsic evidence bar and is potentially admissible.15

The DC Court of Appeals’ result is largely correct and should be adopted by other courts, but its classification of this evidence as a type of bias evidence is misleading and obscures the justification for the rule. Corruption is not bias, but rather a historically and doctrinally distinct species of impeachment. In addition, the DC Court of Appeals has not paid attention to whether the witness was punished for prior perjury. As defended in this Comment, corruption evidence is evidence that tends to show a witness previously committed perjury—or a related act, such as witness tampering or obstruction of justice—for which she either was not punished or was punished less than she could have been. Corruption evidence counters the special credibility that juries attach to witnesses who testify in court and under oath by demonstrating that the witness has less reason to fear the consequences of lying under oath. The lack of prior punishment and the lack of fear of future punishment are generally caused by a relationship between the witness and the government—such as when the witness is a police officer or a government informant. While bias evidence demonstrates that the witness has a special motive to lie, corruption evidence contradicts the inference that the witness has a special motive to tell the truth.

Resurrecting corruption as a valid theory of impeachment that is exempt from the extrinsic evidence bar will increase many witnesses’ incentives to be truthful and will reduce the systemic bias created by prosecutors’ decisions not to charge government witnesses with perjury.16 Resurrecting corruption will also address some of the problems with the current, artificially enlarged extrinsic evidence bar that have caused some judges—led by Judge Richard Posner of the Seventh Circuit17—to adopt a constrained definition of extrinsic evidence. This constrained definition has allowed extrinsic evidence to be smuggled in through cross-examination.18 Posner’s approach has strong appeal as a matter of policy, but corruption impeachment provides a more solid analytical basis for the result. At the same time, admitting extrinsic evidence of corruption will not violate FRE 404(b),19 require jurors to make careful distinctions between character inferences and corruption inferences,20 or overwhelm courts with an endless stream of time-consuming disputes over prior acts.21

Part I discusses the historical development and modern understanding of the extrinsic evidence bar, and Part II presents the two modern developments that challenge that understanding: the DC Court of Appeals’ corruption bias cases and attempts by federal courts to circumvent the extrinsic evidence bar by redefining extrinsic evidence. Part III argues that corruption impeachment should be accepted by federal and state courts, while Part IV responds to objections to the argument. Finally, Part V explores the practical issues courts will face in evaluating the admissibility of corruption impeachment when the evidence is less clear-cut than in the hypothetical explored above.

  • 1. Perjury occurs when a person either willfully testifies under oath to a material matter which she does not believe to be true or, in a declaration under penalty of perjury, gives information identified as true that she does not believe to be true. See 18 USC § 1621.
  • 2. See FRE 402. For the definition of “relevant evidence,” see FRE 401 (“Evidence is relevant if: (a) it has any tendency to make a fact more or less probable . . . and (b) the fact is of consequence in determining the action.”).
  • 3. FRE 403.
  • 4. See, for example, FRE 802 (providing that hearsay is presumptively inadmissible); FRE 803–04 (creating specific exceptions to the general rule against hearsay).
  • 5. FRE 404(b)(1).
  • 6. FRE 404(b)(2).
  • 7. FRE 608(b).
  • 8. Extrinsic evidence is anything other than the witness’s own testimony about the prior act, including the testimony of another witness. For discussion of a complication in this definition, see Part II.B.
  • 9. See FRE 609 (providing for certain circumstances in which “evidence of a criminal conviction” may be introduced to “attack[ ] a witness’s character for truthfulness”).
  • 10. See Edward J. Imwinkelried, Formalism versus Pragmatism in Evidence: Reconsidering the Absolute Ban on the Use of Extrinsic Evidence to Prove Impeaching, Untruthful Acts That Have Not Resulted in a Conviction, 48 Creighton L Rev 213, 222–23 (2015).
  • 11. “Motive to lie” is shorthand for a collection of motives that need not operate consciously. Biases and other motives can influence a witness to subconsciously slant or distort the truth in ways that fall short of outright lies.
  • 12. The Second and Tenth Circuits treat FRE 404(b) as applying only to substantive evidence, not evidence that is admitted for impeachment purposes. See United States v Watson, 766 F3d 1219, 1244–46 (10th Cir 2014); United States v Schwab, 886 F2d 509, 511 (2d Cir 1989). See also David A. Moran, Evidence, 1993 Detroit Coll L Rev 703, 710 (describing FRE 404(b) as applying to evidence “admitted for substantive purposes” and FRE 608(b) and 609(a) as applying to evidence offered “to impeach witnesses”). The Third, Fourth, and Eleventh Circuits, on the other hand, hold that FRE 404(b) does apply to impeachment evidence, thus implying that FRE 608(b) functions as an exception to the general rule. See United States v Bradley, 644 F3d 1213, 1273 (11th Cir 2011); United States v Stockton, 788 F2d 210, 219 n 15 (4th Cir 1986); Pounds v Board of Trustees, 2000 WL 655936, *4 (4th Cir); United States v Shannon, 766 F3d 346, 352 n 9 (3d Cir 2014). See also FRE 404, Advisory Committee Notes to the 1991 Amendment (“The amendment requires the prosecution to provide notice, regardless of how it intends to use the extrinsic act evidence at trial, i.e., during its case-in-chief, for impeachment, or for possible rebuttal.”).
  • 13. See, for example, United States v Watler, 461 F3d 1005, 1009–10 (8th Cir 2006) (holding that the defense should have been able to introduce the fact that a witness had threatened to kill the defendant because “a death threat suggests personal animus,” although ultimately finding that the error was harmless).
  • 14. The DC Court of Appeals, not to be confused with the United States Court of Appeals for the DC Circuit, is the local appellate court in the District of Columbia. It hears appeals from the DC Superior Court, and its decisions may be appealed to the United States Supreme Court. See 28 USC § 1257.
  • 15. See, for example, Longus v United States, 52 A3d 836, 852–53 (DC 2012). For DC’s common-law version of FRE 608(b), see Sherer v United States, 470 A2d 732, 738 (DC 1983).
  • 16. See Part III.D.
  • 17. See text accompanying notes 142-46.
  • 18. See Parts II.B, III.E.
  • 19. See Part IV.A.
  • 20. See Part IV.B.
  • 21. See Part IV.C.