词源与由来: From Old French 'empechier' meaning 'to hinder or prevent,' from Late Latin 'impedicare' (to entangle or fetter the feet), from 'pedica' (a shackle).
Impeachment is a central tactic during cross-examination. Any party may impeach any witness, including their own (since the abolition of the voucher rule by Rule 607). The most dramatic form is impeachment by prior inconsistent statement, where counsel confronts the witness with a contradictory statement made earlier — in a deposition, police report, or prior testimony. The cross-examiner must give the witness an opportunity to explain or deny the inconsistency. Impeachment by bias reveals that the witness has a motive to favor one party. Impeachment by prior conviction under Rule 609 requires the court to balance probative value against prejudicial effect for most felonies.
Attorney: "Mr. Foster, you testified today that the light was red. Do you recall giving a deposition in this case on January 10th?" Witness: "Yes." Attorney: "And at that deposition, page 47, line 12, didn't you say, under oath, 'The light was green'?" Witness: "I... I may have been confused."
Attorney: "Isn't it true that the plaintiff is your sister-in-law?" Witness: "Yes." Attorney: "And isn't it true that you stand to benefit financially if she wins this lawsuit?" — Impeachment by bias.
Attorney: "Mr. Harris, you were convicted of fraud in 2021, correct?" Witness: "Yes." Attorney: "That's a crime involving dishonesty, isn't it?" — Impeachment by prior conviction under Rule 609(a)(2).
Students often confuse impeachment with substantive evidence. A prior inconsistent statement used solely for impeachment is not admitted for its truth — it only attacks credibility. However, if the prior statement was made under oath at a proceeding (Rule 801(d)(1)(A)), it may be admitted as substantive evidence as well.
United States v. Abel, 469 U.S. 45 (1984)
Held that evidence of witness bias is always admissible for impeachment and that membership in an organization whose tenets require perjury on behalf of members is relevant to show bias.
Davis v. Alaska, 415 U.S. 308 (1974)
Held that a criminal defendant's Sixth Amendment right to cross-examine witnesses for bias outweighs state policies protecting juvenile records, ensuring the right to expose witness motivation.
Olden v. Kentucky, 488 U.S. 227 (1988)
Reinforced that the right to impeach through evidence of bias is a fundamental component of the Confrontation Clause, reversing a conviction where the defendant was prevented from showing the accuser's motive to lie.
What are the different methods of impeaching a witness?
The main methods of impeachment are: bias or interest, prior inconsistent statements, contradiction by other evidence, defects in perception or memory, character for untruthfulness (reputation or opinion under Rule 608), and prior convictions (Rule 609). Each method attacks credibility from a different angle.
Can you impeach your own witness?
Yes, under Rule 607, any party may impeach any witness, including their own. The old common law "voucher rule" that prohibited impeaching one's own witness was abolished by the Federal Rules. However, a party cannot call a witness solely for the purpose of impeaching them with otherwise inadmissible evidence.
What prior convictions can be used for impeachment under Rule 609?
Under Rule 609, crimes involving dishonesty or false statement (fraud, perjury, forgery) are automatically admissible for impeachment regardless of the sentence. Other felonies are admissible subject to Rule 403 balancing (for non-defendant witnesses) or a stricter balancing requiring probative value to outweigh prejudice (for criminal defendants).
What is the difference between impeachment and substantive evidence?
Impeachment evidence is admitted solely to attack a witness's credibility — the jury may not consider it as proof of the facts stated. Substantive evidence is admitted for its truth. Some evidence (like prior sworn inconsistent statements under Rule 801(d)(1)(A)) can serve both purposes simultaneously.
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