Expert reliability (Rule 702, Daubert, Joiner, Kumho), judicial notice (Rule 201), and the spousal testimonial privilege (Trammel)

Black-letter propositions

1. 01

   A witness qualified as an expert by knowledge, skill, experience, training, or education may give an opinion if the proponent shows that it is more likely than not that the testimony will help the trier of fact, is based on sufficient facts or data, is the product of reliable principles and methods, and reflects a reliable application of those principles and methods to the facts.

2. 02

   The Federal Rules of Evidence and not the Frye general-acceptance test provide the standard for admitting expert scientific testimony in federal court, and the judge acts as a gatekeeper to ensure that expert testimony rests on a reliable foundation and is relevant.

3. 03

   Factors relevant to reliability include whether the theory or technique can be and has been tested, whether it has been subjected to peer review and publication, its known or potential error rate and standards controlling its operation, and whether it has attracted widespread acceptance in the relevant community, but the inquiry is flexible and focuses on principles and methodology, not on the conclusions they generate.

4. 04

   The gatekeeping obligation applies to all expert testimony, including that of engineers and other nonscientists, and the Daubert factors may be considered but are not a definitive checklist and may or may not be pertinent depending on the expert and the subject.

5. 05

   A court need not admit opinion evidence connected to existing data only by the expert's own say-so, and a trial judge's decision to admit or exclude expert evidence is reviewed for abuse of discretion.

6. 06

   Cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof, and not wholesale exclusion, are the appropriate means of challenging evidence that rests on valid principles.

7. 07

   A court may judicially notice a fact that is not subject to reasonable dispute because it is generally known within the trial court's territorial jurisdiction or can be accurately and readily determined from sources whose accuracy cannot reasonably be questioned.

8. 08

   The court may take judicial notice on its own and must do so if a party requests it and supplies the necessary information, and the court may do so at any stage of the proceeding, and a party on timely request is entitled to be heard on the propriety of taking notice.

9. 09

   In a civil case the court must instruct the jury to accept a noticed fact as conclusive, but in a criminal case the court must instruct the jury that it may or may not accept the noticed fact as conclusive.

10. 10

    In federal criminal cases the witness-spouse alone has a privilege to refuse to testify adversely to the defendant spouse, so the defendant cannot prevent a spouse from testifying and the witness may be neither compelled to testify nor foreclosed from testifying, and a spouse who chooses to testify does so voluntarily even after a grant of immunity.

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Common wrong turns

• General acceptance is not the sole test for scientific evidence under the federal rules.
• Daubert reliability screening applies to nonscientific experts too.
• An expert's opinion linked to the data only by the expert's own say-so can be excluded.
• In a criminal case the jury may reject a judicially noticed fact, unlike in a civil case.

Worked example

In a federal prosecution, a wife whom the defendant married years ago is offered to testify against him and agrees to do so voluntarily after receiving a promise of leniency. The defendant invokes the marital testimonial privilege.

Practice this topic

Rule 702 and Daubert

Rule 702 permits an expert to testify if the proponent demonstrates that it is more likely than not that the expert's specialized knowledge will help the trier of fact, that the testimony is based on sufficient facts or data, that it is the product of reliable principles and methods, and that the opinion reflects a reliable application of the principles and methods to the facts.

Daubert v. Merrell Dow Pharmaceuticals held that the Federal Rules of Evidence and not the Frye test provide the standard for admitting expert scientific testimony and that the judge must ensure that the testimony rests on a reliable foundation and is relevant, and it listed considerations including testing, peer review and publication, error rate and standards, and widespread acceptance, in a flexible inquiry that focuses on principles and methodology and not on conclusions. It also said cross-examination, contrary evidence, and careful instruction are the appropriate means of challenging evidence based on valid principles.

Later expert decisions

General Electric Co. v. Joiner held that abuse of discretion is the standard for reviewing a decision to admit or exclude expert scientific evidence and that nothing in Daubert or the rules requires a court to admit opinion evidence connected to existing data only by the ipse dixit of the expert.

Kumho Tire Co. v. Carmichael held that the Daubert gatekeeping obligation applies to all expert testimony and not just scientific testimony, that the Daubert factors may apply to the testimony of engineers and other experts who are not scientists, and that they are not a definitive checklist and may or may not be pertinent depending on the nature of the issue, the expert's expertise, and the subject of the testimony.

Judicial notice and spousal testimony

Rule 201 permits judicial notice of a fact not subject to reasonable dispute because it is generally known within the trial court's territorial jurisdiction or can be accurately and readily determined from sources whose accuracy cannot reasonably be questioned, allows notice on the court's own or on a party's request with the necessary information, at any stage, with an opportunity to be heard, and requires the jury in a civil case to be instructed to accept the fact as conclusive and in a criminal case to be told it may or may not accept it as conclusive.

Trammel v. United States modified the earlier rule so that the witness-spouse alone has a privilege to refuse to testify adversely to the other spouse, held that the witness may be neither compelled to testify nor foreclosed from testifying, and held that the wife's testimony after a grant of immunity and assurances of lenient treatment was not involuntary.

Frequently asked questions