Also known as: collateral matter · collateral issue
Written by attorneys · grounded in primary & secondary sources — see below
A fact or circumstance that does not affect the essential character of conduct or bear on any material issue in a case. Consent induced by fraud or mistake as to such a matter remains effective. Extrinsic proof contradicting a witness on such a matter is ordinarily excluded to avoid confusion and delay.
Catherine Carter agreed to let Carlos Castillo photograph her for a modeling portfolio after he assured her the images would remain private. Castillo later sold the photos to a magazine. Because the misrepresentation concerned only the subsequent use of the images and not the essential character of the photography session itself, Carter's consent barred her battery claim.
Cameron Cruz testified on direct examination that he had never possessed the drugs found in his car. The government sought to introduce his earlier statement admitting possession for impeachment. Because the prior statement directly contradicted testimony on a central fact, the court permitted its use even though the statement had been obtained in violation of Miranda.
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Chloe Chen took the stand and denied making any incriminating statements to police. The prosecution offered her earlier statements taken without proper warnings. The court allowed the statements to impeach her testimony on the events in question because the statements bore directly on the charged conduct rather than a peripheral point.
Cecilia Cabrera testified that she had seen the defendant at the scene. The defense offered evidence that she had once misidentified a different person in an unrelated matter. The court excluded the evidence because the prior misidentification was a collateral matter bearing only on general credibility and not on any issue in the present case.
Extrinsic evidence is generally excluded when the matter is collateral because it does not bear on any material issue and risks confusing the jury or wasting time. The trial judge retains discretion under Rule 403 to exclude such proof even when the Federal Rules do not expressly codify the common-law collateral-matter bar. Direct contradiction on a fact placed in issue by the witness's own testimony is not treated as collateral.
Supporting sources
No. Otherwise inadmissible evidence may be used to impeach a defendant on matters raised during direct testimony. The rule against collateral impeachment does not shield a defendant who opens the door by testifying about facts that can be contradicted by otherwise excludable proof.
Supporting sources
Consent induced by fraud or mistake remains valid when the misrepresentation concerns only a collateral matter that does not change the essential character of the conduct. The rule preserves the effectiveness of consent in such circumstances while allowing rescission when the fraud goes to the nature of the invasion itself.
Supporting sources
…on the Government’s disability to challenge his credibility.” 347 U. S., at 65. It is true that Walder was impeached as to collateral matters included in his direct examination, whereas petitioner here was impeached as to testimony bearing more directly on the crimes charged. We are not persuaded that there is a difference in…