Who Can Attack Credibility?
but you can’t….
Any party can attack the credibility of any witness, including their own.
But: You can’t call a witness just to impeach them
Impeachment evidence is not
substantive proof (it doesn’t prove facts of the case)
4 Common Ways to Impeach a Witness
A. Perception
B. Memory
C. Narration
D. Sincerity / Truthfulness
Prior Convictions (Rule 609)
certain criminal convictions can be used to attack a witness’s credibility.
Typically allowed if the crime involved dishonesty or false statements.
The judge weighs probative value vs. prejudice under Rule 403.
Prior Untruthful Acts (Rule 608(b))
These are specific dishonest acts (like lying on a job application or cheating on taxes).
You cannot prove them with extrinsic evidence (like documents or witnesses).
But the cross-examiner may ask about them if the act is probative of truthfulness.
Example: “Isn’t it true you lied on your police report?”
It’s up to the judge’s discretion whether to allow the question.
Untruthful Reputation or Opinion (Rule 608(a))
A witness’s character for truthfulness can be attacked through reputation or opinion testimony.
Example: Another witness testifies, “In our community, she’s known as dishonest.”
Bias, Interest, Prejudice, or Motive
You can show that a witness has a reason to lie (for example, personal interest, hatred, or loyalty).
Example: A witness testifying for a friend, or hoping for leniency in their own case.
Bias is always relevant to credibility and is not a collateral matter, so extrinsic evidence is allowed.
Prior Convictions
Can Use Extrinsic Evidence?
Sometimes
Allowed for crimes involving dishonesty or false statements
Prior Untruthful Acts Can Use Extrinsic Evidence?
❌ No
May ask on cross, but cannot prove with other evidence
Reputation/Opinion for Untruthfulness
Can Use Extrinsic Evidence?
✅ Yes
Must come from someone who knows the witness’s reputation
Prior Inconsistent Statements
Can Use Extrinsic Evidence?
✅ Sometimes
Only if non-collateral and after giving a chance to explain/deny
Bias/Interest/Motive
Can Use Extrinsic Evidence?
✅ Yes
Always relevant, not collateral
Narrative - Prior Inconsistent Statements
- Identify inconsistency
Find conflict between prior and current statement - Confront witness
Ask about it (no need to show statement yet) - Allow explanation/denial
Witness must get a chance to respond - Use extrinsic evidence (if needed)
Only if witness denies and it’s not collateral - Limiting instruction
Jury can use it only for credibility, not truth
You can’t use extrinsic evidence just to
contradict a witness on a collateral issue.
General Rule of silence
A witness’s or defendant’s silence can sometimes be treated as inconsistent with their later testimony — meaning the silence can be used to impeach their credibility.
If a witness stays silent when asked a question before trial but answers at trial, that silence can be seen as inconsistent with their testimony… if…
A reasonable person in that situation would have responded, and
The silence was not due to confusion, fear, or another reasonable explanation.
Pre-Arrest Silence
the defendant’s pre-arrest silence may not be used as substantive evidence of guilt
— but it may be used for impeachment if the defendant later testifies inconsistently.
Post-Arrest, Pre-Miranda Silence
ust like pre-arrest silence, this type of silence cannot be used as substantive evidence of guilt,
but it can be used to impeach the defendant if they testify inconsistently.
Post-Arrest, Post-Miranda Silence
Once the defendant has been arrested and given Miranda warnings,
their silence may not be used for any purpose — not to prove guilt and not even to impeach.
untruthfulness 4 categories
- bias
- reputation to lie
- past untruthful act
- prior criminal convictions
