## Facts

- A Marine Midland Bank branch in Buffalo, New York, was robbed on April 22, 1975 by a person disguised as a woman.
- A bank teller described the robber’s physical features and disguise but could not positively identify Ronald William Harvey as the robber.
- The prosecution’s only witness who positively identified Harvey was Priscilla Martin, who testified she saw Harvey near the bank around the time of the robbery.
- Martin had known Harvey for about 19 years and had previously lived with him.
- The defense theory was that Martin harbored hostility and had a motive to fabricate tied to a personal dispute involving paternity and child support and alleged threats to “take revenge.”
- On cross-examination, Martin denied having trouble with Harvey, accusing him of fathering her child and refusing support, or making revenge threats to his mother.
- The defense sought to call Harvey’s mother to testify that Martin had made the accusations and threats, to show Martin’s bias and motive to testify falsely.
- The trial court excluded the mother’s testimony as “collateral” impeachment.
- The jury convicted Harvey of bank robbery and bank larceny arising from the same incident.

## Issues

1. Whether the trial court committed reversible error by excluding extrinsic defense evidence offered to prove bias and motive to falsify of the government’s principal identification witness as “collateral.”
2. Whether any error in excluding the bias evidence was harmless given the remaining evidence.

## Decision

- The Second Circuit reversed the convictions and remanded for a new trial.
- The court held the exclusion of the mother’s testimony was error because it was directed to bias, not a merely collateral contradiction.
- The court further held the error was not harmless because the prosecution’s case depended heavily on Martin’s credibility as the sole positive identification witness.

## Legal Principles

- Evidence showing a witness’s bias, hostility, or motive to testify falsely is generally not treated as “collateral” and may be proved through extrinsic evidence.
- Trial courts have discretion to limit otherwise relevant impeachment evidence, but that discretion is constrained when the evidence concerns bias of a central prosecution witness and is highly probative.
- When the government’s proof turns largely on the credibility of a single identification witness, improper restrictions on bias impeachment can require reversal because the jury’s ability to assess credibility is materially impaired.

## Conclusion

The court ordered a new trial because the defense was improperly prevented from presenting extrinsic evidence that the government’s key identification witness had a personal motive to harm the defendant, and the prosecution’s case relied so strongly on that witness that the limitation could not be treated as harmless.


United States v. Harvey, 547 F.2d 720 (2d Cir. 1976)