Chapter 4: Witness Competency, Qualification, Examination

Rule 601: Competency to Testify in General

Every person is competent to testify unless rules provide otherwise.

In civil cases, state law governs competency where state law governs rule of decision.

If state law is “procedural,” forum state competency law will apply.

If state law is “substantive,” state where injury happened might apply.

Rule 606: Juror’s Competency as Witness

• Jurors cannot testify as a witness at trial before the other jurors. If they do, parties must be given opportunity to object.

• During inquiry into validity of verdict/indictment:

  • Jurors cannot testify about statements made during deliberations, mental state considerations, votes

  • Exceptions:
    - Introduction of improper prejudicial information to jury
    - Outside influence
    - Mistake made on jury form

Rule 605: Judge’s competency as witness

Presiding judges cannot testify as witnesses during trial.
(Does not mean literally taking the stand as a witness, also means their own personal comments)

Parties need not object to preserve the issue (can bring this up later)

Rule 611: Mode and Order of Examining Witnesses and Presenting Evidence

• Court has discretion to control examination of witnesses and evidence as to:
  - Avoid undue embarrassment and harassment
  - Avoid wasting time
  - Make effective truthfinding procedures

• Scope:
  - Cross should not go beyond scope of direct exam/witness credibility (unless court says otherwise)

• Leading question:
  - Only on cross-exam
  - When party introduces hostile witness/adverse party

Rule 612: Writing Used to Refresh Witness

When a witness uses a writing to refresh memory:
Scope
- Before testimony: court has discretion
- While testifying: automatic right to

Rights of adverse party:
- entitled to have the writing produced at hearing
- inspect it
- cross-examine witness
- introduce relevant part of writing based on witness testimony

Rule 602: personal knowledge

Witness may only testify to a matter if there is evidence that the witness has personal knowledge of the matter.

Without PK, could fall within hearsay exception, but the chain of hearsay must end with someone who has personal knowledge.

Rule 614: Court Calling/Examining a Witness

• Court can call its own witnesses

• Court can examine a witness no matter who brings the witness

• Party can object to the court’s calling of a witness.

Rule 701: Opinion Testimony by Lay Witnesses

Non expert testimony about opinion:
- Rationally based on witness’s perception
- helpful to clearly understanding the fact at issue (helpfulness requirement)
- Not based on specialized scientific or technical knowledge

Collective Facts Doctrine

Some concepts can only be easily explained via inferences, vs. in a fact-like manner.

These inferential “collective facts” are ok because they are more helpful.

I.e. instead of “brow furrowed, frowning face, increased heart rate", you can just say “he is angry” as a “collective fact.”

Rule 702: Testimony by Expert Witness

Expert witnesses who are qualified by training, experience, etc. may testify in the form of an opinion if the proponents demonstrates that it is more likely than not that:
- expert’s scientific, technical, or other knowledge will help jury understand evidence or fact at issue
- testimony is based on facts and data
- testimony is the result of reliable principles and methods
- the expert’s opinion reflects a reliable application to facts of case

Cannot actually call the witness an “expert” for prejudicial impact

Cannot admit information that is just within the general knowledge of jurors

Frye Standard

General Acceptance test:
- Is this expert’s testimony generally accepted within the field that they are in.

Tanner v. US

Juror wants to report that the other jurors were deeply intoxicated during the deliberations.

Denied under rule 606.

Alcohol or other substance intoxication is not an admissible “outside influence” for the purposes of impeaching a jury decision.

Pena Rodriguez v. CO

• Juror testimony about other juror’s deep racial animus IS admissible and can overcome Rule 606 (no impeachment rule).

• In this case, one juror kept talking about their belief that Mexicans were inherently criminal

Daubert v. Dow Pharmaceuticals (Daubert Standard)

• Replaces the Frye general acceptance test

• Creates factors to consider for admissibility of the expert testimony:

  • Whether the technique or theory in question can be, and has been tested;

  • Whether it has been subjected to publication and peer review;

  • Its known or potential error rate;

  • The existence and maintenance of standards controlling its operation; and

  • Whether it has attracted widespread acceptance within a relevant scientific community.

Rule 703: Bases for Expert Witness Testimony

• Experts can base their testimony off of things that they have personally seen or observed.

  • 4 categories:

  • first hand observation

  • presentation at trial (testimony heard by expert, or a hypothetical)

  • outside data known to expert prior to trial

• If this is something other experts in the field would reasonably rely on those facts or data, it need not be admissible for the opinion to be admitted.

• If the basis would be otherwise inadmissible, the proponent may disclose them to the jury only if the probative value in helping jury understand the information outweighs prejudicial effect.

Rule 705: Disclosing the Facts or Data Underlying an Expert

• Experts may state opinion without testifying to underlying facts or data.

• May be required to disclose that information on cross-examination.

Rule 704: Ultimate Issue

• Experts stating what the “ultimate issue” to be determined in a case is not automatically inadmissible.

• Exception: Experts cannot state opinions about whether the D had the requisite mental state for an offense/defense.

Diaz v. US

• Diaz is caught with drugs in her car, she claims ignorance.

• Expert witness says “most traffickers know that there are drugs in the car.”

• This is NOT a 704 violation, because “most traffickers” is a generalization, not specifically about Diaz.

Rule 707 (proposed): Machine Generated Evidence

• If machine generated evidence (like AI) is offered without an expert witness, and would be subject to 702 if brought by an expert witness, the court may admit only if the evidence meets the requirements of 702.

• Does not apply to simple output of scientific instruments.

Rule 615: Excluding Witnesses

• At a party’s (or court’s) request, court must exclude witnesses from the courtroom to not hear the testimony of other witnesses.

• Cannot exclude another party or a representative for the party

• Cannot exclude someone a party deems necessary for presenting their claim

• Cannot exclude someone deemed by statute to be present.

Can also block excluded witnesses from accessing trial testimony later, or disclosure of trial testimony to those witnesses. (Sequestration)