10.3 Witness Competence, Impeachment Methods & Expert Opinion
Key Takeaways
- Under FRE 601, every person is presumed competent to testify as a witness; witnesses must possess personal knowledge of the matter (FRE 602) and take an oath or affirmation to testify truthfully (FRE 603); under FRE 606(b), juror testimony to impeach a verdict is barred except for extraneous prejudicial information, improper outside influence, clerical mistakes, or clear racial animus (Peña-Rodriguez).
- The seven classic methods of impeachment are: (1) Prior Inconsistent Statements (FRE 613), (2) Bias or Interest, (3) Sensory/Mental Defects, (4) Character for Untruthfulness via Reputation/Opinion (FRE 608(a)), (5) Specific Bad Acts Probative of Untruthfulness on Cross (FRE 608(b)), (6) Criminal Convictions (FRE 609), and (7) Contradiction.
- Under FRE 608(b), a witness may be cross-examined regarding specific unconvicted bad acts probative of truthfulness (e.g., filing a false tax return), but the cross-examiner must take the witness's answer and is strictly prohibited from introducing extrinsic evidence to prove the bad act.
- Under FRE 609, prior convictions involving dishonesty or false statement (crimen falsi) are automatically admissible against any witness without 403 discretion; non-crimen falsi felonies are admissible against a criminal defendant only if probative value outweighs prejudicial effect, and against other witnesses under standard 403; convictions older than 10 years require reverse-403 balancing and written notice.
- Present Recollection Refreshed (FRE 612) allows any item to refresh memory without admission as evidence; Past Recollection Recorded (FRE 803(5)) allows a contemporaneous, accurate record to be read into evidence when memory fails; Expert Opinion (FRE 702) requires Daubert reliability and helpfulness, but experts may not give opinions on criminal mental states under FRE 704(b).
10.3 Witness Competence, Impeachment Methods & Expert Opinion
Witness testimony is the primary vehicle for introducing factual evidence at trial. To testify, a witness must satisfy the threshold requirements of competence, personal knowledge, and oath. Once a witness testifies, their credibility is subject to attack through established impeachment methods. Furthermore, the Federal Rules of Evidence govern the use of memory aids and define the boundaries between lay opinion and expert opinion testimony.
1. Witness Competence & Juror Disqualification
General Competency (FRE 601, 602, 603)
- Presumption of Competence (FRE 601): Every person is presumed competent to be a witness regardless of age, mental capacity, or religious belief. In civil actions where state law supplies the rule of decision (diversity cases), state competency rules (such as Dead Man's Statutes) apply.
- Personal Knowledge (FRE 602): A lay witness may testify to a matter only if evidence is introduced sufficient to support a finding that the witness has personal knowledge (perceived through their own senses: sight, hearing, smell, touch).
- Oath or Affirmation (FRE 603): The witness must declare that they will testify truthfully by oath or affirmation in a form calculated to awaken the witness's conscience.
Juror and Judge Disqualification (FRE 605 & FRE 606)
- Presiding Judge (FRE 605): The presiding judge may not testify as a witness at the trial.
- Juror Non-Impeachment Rule (FRE 606(b)): During an inquiry into the validity of a verdict or indictment, a juror may not testify about:
- Any statement made or incident that occurred during jury deliberations;
- The effect of anything on that juror's or another juror's mental processes; or
- Any juror's mental processes concerning the verdict.
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| JUROR VERDICT IMPEACHMENT (FRE 606(b)) |
| |
| GENERAL RULE: Juror testimony is STRICTLY PROHIBITED to impeach verdict |
| (e.g., misinterpreting instructions, coin flips, intoxication, coercion). |
| |
| PERMISSIBLE EXCEPTIONS (Extrinsic Inquiries): |
| [+] Extraneous prejudicial information improperly brought to jury's |
| attention (e.g., reading unauthorized news articles, independent web).|
| [+] An outside influence was improperly brought to bear on any juror |
| (e.g., bribes, threats, private communication by bailiff). |
| [+] A clerical mistake was made in entering the verdict onto the form. |
| [+] Peña-Rodriguez Constitutional Exception: Clear statement showing |
| that racial animus / bias was a motivating factor in a juror's vote. |
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2. The Seven Methods of Impeachment
Impeachment is the process of discrediting a witness's testimony by demonstrating that the witness is unworthy of belief. The table below delineates the seven methods of impeachment and their respective extrinsic evidence rules.
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| IMPEACHMENT METHODS COMPARISON TABLE |
| |
| METHOD LEGAL STANDARD & FRE PROVISION EXTRINSIC EVIDENCE PERMISSIBILITY |
| ------------------- ----------------------------------- ------------------------------------- |
| 1. Prior FRE 613: Inconsistency between Admissible IF witness is given an |
| Inconsistent trial testimony and prior statement. opportunity to explain/deny and |
| Statement Substantive if sworn (801(d)(1)(A)). adverse party can cross-examine. |
| ------------------- ----------------------------------- ------------------------------------- |
| 2. Bias, Interest, Common Law: Relationship, financial ALWAYS ADMISSIBLE via extrinsic |
| or Motive stake, hostility, or plea deal. evidence (must confront on cross). |
| ------------------- ----------------------------------- ------------------------------------- |
| 3. Sensory / Mental Common Law: Impaired sight, hearing, ALWAYS ADMISSIBLE via extrinsic |
| Defects intoxication, or memory deficiency. evidence. |
| ------------------- ----------------------------------- ------------------------------------- |
| 4. Reputation / FRE 608(a): Character witness Admissible via testimony of a |
| Opinion for testifies to untruthful character. reputation/opinion witness (no |
| Untruthfulness Cannot bolster until attacked! specific bad acts on direct). |
| ------------------- ----------------------------------- ------------------------------------- |
| 5. Specific Bad Acts FRE 608(b): Inquiring on cross into EXTRINSIC EVIDENCE STRICTLY BARRED! |
| of Untruthfulness unconvicted acts probative of truth. Must take witness's answer. |
| ------------------- ----------------------------------- ------------------------------------- |
| 6. Prior Criminal FRE 609: Conviction of felony or Admissible via public record or |
| Conviction crimen falsi within 10-year window. admission on cross-examination. |
| ------------------- ----------------------------------- ------------------------------------- |
| 7. Contradiction Showing witness made factual error Admissible unless the matter is |
| regarding a trial fact. purely collateral (extrinsic barred). |
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Detailed Analysis of Critical Impeachment Rules
A. Prior Inconsistent Statements (FRE 613 vs. FRE 801(d)(1)(A))
- Impeachment Purpose (FRE 613): Any prior inconsistent statement (oral, written, sworn, or unsworn) may be used to impeach the credibility of a testifying witness. Extrinsic evidence of the statement is admissible provided the witness is given an opportunity to explain or deny the statement and the adverse party is given an opportunity to examine the witness.
- Substantive Use (FRE 801(d)(1)(A)): A prior inconsistent statement is admissible for its substantive truth (as non-hearsay) only if it was given under penalty of perjury at a trial, hearing, other proceeding, or in a deposition.
B. Specific Bad Acts Probative of Untruthfulness (FRE 608(b))
- Rule Scope: On cross-examination, an attorney may inquire into specific unconvicted instances of conduct if they are probative of the character for truthfulness or untruthfulness of the witness (or another witness whose character the witness being cross-examined has testified about).
- Permissible Subjects: Filing a false tax return, forging a signature, lying on a job application, using a fake ID, academic cheating.
- Impermissible Subjects: Violent crimes (assault, battery), drug possession, drunk driving (these show bad character or lawlessness, but not untruthfulness).
- The "Take the Answer" Rule: The cross-examiner cannot introduce extrinsic evidence to prove the bad act occurred if the witness denies it. Document exhibits and outside witness testimony are strictly inadmissible under Rule 608(b).
C. Impeachment by Prior Criminal Conviction (FRE 609)
FRE 609 establishes a precise three-tier framework governing the admissibility of criminal convictions to impeach a witness's character for truthfulness.
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| FRE 609 CONVICTION DECISION TREE |
| |
| IS CONVICTION A CRIMEN FALSI (Dishonesty or False Statement)? |
| (e.g., Perjury, Fraud, Forgery, Embezzlement, False Pretenses) |
| -> YES: MANDATORY ADMISSION against ANY witness in civil or criminal case.|
| (No judicial discretion, no 403 balancing, regardless of penalty).|
| -> NO: Is it a FELONY (punishable by death or imprisonment > 1 year)? |
| * If NO (Misdemeanor non-dishonesty): CATEGORICALLY INADMISSIBLE. |
| * If YES (Felony): Evaluate identity of witness: |
| |
| FELONY BALANCING TIERS: |
| [ TIER 1: CRIMINAL DEFENDANT TESTIFYING ] |
| Admissible ONLY IF probative value OUTWEIGHS prejudicial effect. |
| (Prosecution bears the burden; stricter than Rule 403). |
| |
| [ TIER 2: ANY OTHER WITNESS (Civil parties, ordinary witnesses) ] |
| Admissible subject to standard FRE 403 (Excluded only if danger of |
| unfair prejudice SUBSTANTIALLY OUTWEIGHS probative value). |
| |
| [ TIER 3: THE 10-YEAR STALE CONVICTION RULE (FRE 609(b)) ] |
| If > 10 years elapsed since conviction or release from prison (later): |
| Inadmissible UNLESS probative value SUBSTANTIALLY OUTWEIGHS prejudicial |
| effect (Reverse-403 favoring exclusion) AND Proponent gives ADVANCE NOTICE|
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3. Present Recollection Refreshed vs. Past Recollection Recorded
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| REFRESHED RECOLLECTION VS. RECORDED RECOLLECTION |
| |
| DIMENSION FRE 612 (REFRESHED) FRE 803(5) (RECORDED) |
| ------------------ --------------------------- ----------------------- |
| Witness Memory Memory is refreshed; Memory fails; witness |
| witness testifies live. cannot recall presently. |
| Permitted Item ANYTHING (writing, photo, Writing made or adopted |
| scent, physical object). by witness when fresh. |
| Evidentiary Status Item is NOT admitted as an Record is READ INTO |
| for Proponent exhibit by proponent. evidence as an exhibit. |
| Adverse Party May inspect, cross-examine, May inspect and OFFER the|
| Rights and offer relevant portions. writing AS AN EXHIBIT. |
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4. Lay vs. Expert Opinion Testimony
Lay Opinion Testimony (FRE 701)
If a witness is not testifying as an expert, opinion testimony is restricted to opinions that are:
- Rationally based on the witness's perception (first-hand sensory observation);
- Helpful to clearly understanding the witness's testimony or to determining a fact in issue; and
- Not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.
- Classic Permissible Lay Opinions: Physical appearance, emotional state, voice/handwriting identification, speed of a vehicle, sobriety/intoxication, value of own property.
Expert Opinion Testimony (FRE 702 & Daubert)
Under FRE 702, an expert witness qualified by knowledge, skill, experience, training, or education may testify in the form of an opinion if:
- The expert's specialized knowledge will help the trier of fact understand the evidence or determine a fact in issue;
- The testimony is based on sufficient facts or data;
- The testimony is the product of reliable principles and methods; and
- The expert has reliably applied the principles and methods to the facts of the case.
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| DAUBERT / KUMHO TIRE RELIABILITY FACTORS |
| |
| 1. TESTABILITY: Can the theory or technique be tested (falsifiability)? |
| 2. PEER REVIEW: Has the methodology been subjected to peer review/pub.? |
| 3. ERROR RATE: What is the known or potential rate of error? |
| 4. STANDARDS: Are there established standards controlling the technique? |
| 5. GENERAL ACCEPTANCE: Has it achieved general acceptance in community? |
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Bases of Expert Opinion (FRE 703) & Ultimate Issue Rule (FRE 704)
- Bases of Opinion (FRE 703): An expert may base an opinion on: (1) facts personally observed, (2) facts made known to the expert at trial, or (3) inadmissible facts/data if experts in the particular field would reasonably rely on those kinds of facts in forming an opinion.
- Ultimate Issue Rule (FRE 704(a)): In general, an opinion is not objectionable just because it embraces an ultimate issue to be decided by the trier of fact.
- The Criminal Mental State Exception (FRE 704(b)): In a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense. Those issues are strictly for the trier of fact alone.
A criminal defendant was convicted by a jury of wire fraud. One week after the verdict, a defense investigator obtained a sworn affidavit from Juror A stating that during deliberations, several jurors discussed how the defendant 'looked like a swindler,' that Juror B stated he flipped a coin to decide his guilty vote, and that the jury foreperson brought in an unadmitted newspaper article summarizing the defendant's prior bankruptcies. The defendant files a motion for a new trial based on the affidavit. Which portion of Juror A's affidavit may the court consider under FRE 606(b)?
In a civil breach of contract trial, a key defense witness testified on direct examination that the seller delivered goods that conformed precisely to contract specifications. On cross-examination, the plaintiff's attorney asked the witness: 'Isn't it true that two years ago, you altered dates on your company expense reports to receive $1,500 in unauthorized reimbursements?' The witness replied: 'No, that never happened.' The plaintiff's attorney then seeks to introduce the altered expense report documents into evidence and call the witness's former supervisor to prove the alteration. How should the court rule?
A criminal defendant is on trial for bank robbery. The defendant takes the stand in his own defense and testifies that he was at home during the robbery. On cross-examination, the prosecution seeks to impeach the defendant with a certified record showing that four years earlier, the defendant was convicted of felony aggravated assault (punishable by 5 years imprisonment) and felony embezzlement (punishable by 3 years imprisonment). The defense objects to both convictions. How should the court rule on the admissibility of these convictions under FRE 609?
In a first-degree murder prosecution, the defendant asserts an insanity defense, claiming severe mental disease prevented him from appreciating the wrongfulness of his conduct. The defense calls a qualified forensic psychiatrist who examined the defendant. During direct examination, defense counsel asks the psychiatrist: 'Doctor, based on your examination and psychiatric evaluation, in your professional medical opinion, did the defendant possess the specific intent to kill the victim at the moment of the shooting?' The prosecution objects. How should the court rule?