On bias, extrinsic evidence, and other matters in Longus v. U.S.

Bias is “the powerful distorting effect on human testimony of the witness’ emotions or feelings towards the parties or the witness’ self-interest in the outcome of the case.”  That is McCormick on Evidence, and it is the clearest, most accurate definition I have ever seen of what constitutes bias.

McCormick continues: “[B]ias, or any acts, relationships, or motives reasonably likely to produce it, may be proved to impeach credibility.

Finally, says McCormick, “the right to cross-examine to expose a prosecution witness’s bias has a constitutional dimension.”  McCormick’s source for this last assertion:  the U.S. Supreme Court holding in Davis v. Alaska, 415 U.S. 308, 316 (1974):

The partiality of a witness is subject to exploration at trial, and is always relevant as discrediting the witness and affecting the weight of his testimony.  We have recognized that the exposure of a witness’ motivation in testifying is a proper and important function of the constitutionally protected right of cross-examination.  (Internal quotation marks and citations omitted.)

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Chandra Cooley-Hinton was arrested for drug possession. While in police custody, she told police that she knew something about a recent homicide. Presumably, she was hoping to use this information to secure preferential treatment in her own case. Detective Brown interviewed her. He wrote down in his report that she saw someone who went by the nickname of “L” walk up to the victim and shoot him three times before fleeing the scene.

Cooley-Hinton testified very differently at the defendant’s trial. Specifically, she testified that she was sitting in a parked car getting ready to smoke cocaine when she saw a truck drive by and shoot the victim. There were two people in the truck. She identified the defendant as the driver, not the shooter.

The defense first confronted Cooley-Hinton with the inconsistency between her statement to the detective and her testimony at trial.  Cooley-Hinton denied that she had ever made such a statement to Detective Brown.

The defense then summoned Detective Brown to the stand to impeach Cooley-Hinton’s trial testimony. But the detective contradicted his own report. Cooley-Hinton had in fact told him that “L” was driving, he testified, not walking. That the report said “L” used the term “walked up” instead of “drove up” was a “typographical error.”

Finally, the defense attempted to impeach Detective Brown by asking him about an ongoing government investigation into allegations that he and other officers had coached witnesses to change their stories in another case. The government objected, and the trial court limited the defense to general questions about the existence of the investigation itself. Holding that the specifics of the investigation would constitute inadmissible extrinsic evidence on a collateral issue, the court precluded the defense from asking the detective about the substance of the allegations against him, the status of the investigation, and the potential sanctions the detective would face should the allegations be proven true.

The defendant was ultimately convicted of armed second-degree murder and possession of a firearm during a crime of violence (PFCV). He argued on appeal that:  (1) his Fifth Amendment due process rights were violated when the government failed to correct the detective’s false statement that corroborated Cooley-Hinton’s testimony, and (2) his Sixth Amendment right to confront adverse witnesses was violated by improper limitations on defense counsel’s examination of the detective for corruption and bias.

In Longus v. United States, 52 A.3d 836 (D.C. 2012), the D.C. Court of Appeals declined to rule on the first issue raised by the defendant, holding that the second argument alone was grounds for overturning the conviction and remanding for a new trial.

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“The topic of the collateral fact rule can be confusing.”  So says McCormick.  This is an understatement.  So is the sub-issue of “intrinsic” versus “extrinsic” evidence, so much so that the defense attorney in Longus kept using the term “intrinsic” when what he clearly was referring to was “extrinsic” evidence.

The Sixth Amendment guarantees a defendant in a criminal case the right to confront witnesses against him. Testing the witness’ credibility is an important element of impeachment. And bias is always relevant with respect to credibility.

At the same time, the right to cross-examination is not unlimited, and the trial court has significant discretion to limit the introduction of evidence. To avoid wasting the court’s time on a “trial within a trial,” for example, the trial court may limit evidence on “collateral issues”; namely, those issues that are not directly related to the matter in dispute.

The court may in some cases limit cross-examination to “intrinsic impeachment,” which McCormick defines as requiring the cross-examiner to take the witness’ testimony as it “stands.” In other words, the cross-examiner is unable to introduce evidence independent of the witness’ testimony – e.g., other witnesses or documents – to impeach the witness’ testimony even though that contradictory information might be readily available. This is in contrast to “extrinsic impeachment,” which McCormick defines as “evidence other than through the witness himself.”

Although deciding whether an issue is collateral or non-collateral or whether evidence is intrinsic or extrinsic is always very complicated, the Court in Longus concluded that evidence about the ongoing investigation of Detective Brown’s alleged witness tampering in another case related to bias. And, because bias is always relevant with respect to a witness’ credibility, the defense should have been allowed to introduce extrinsic evidence to impeach the detective:

. . . the trial court’s ruling was based on the erroneous belief that cross-examination about the fact of a pending investigation, without allowing defense counsel to probe into and present extrinsic evidence of the underlying facts, satisfied [the defendant’s] right under the Sixth Amendment to expose all of Detective Brown’s potential biases relevant to his testimony in [the defendant’s] trial.  This cross-examination was probative.  It would have permitted the jury reasonably to infer not only that Detective Brown was motivated to curry favor with the government because he was under criminal investigation, but also that he was not a trustworthy witness as shown by his prior corrupt behavior [during another investigation].