---
title: "Expert Testimony (Daubert Standard)"
type: Legal Rule
source: https://casebriefly.com/legal-rules/expert-testimony-daubert-standard
---

# Expert Testimony (Daubert Standard)

Under FRE 702 and the Daubert framework, expert testimony is admissible if the witness is qualified, the testimony is based on sufficient facts and reliable principles and methods, and the expert has reliably applied those methods to the facts. The trial judge serves as a gatekeeper.

## Definition

Federal Rule of Evidence 702, as interpreted by the Supreme Court's Daubert trilogy, governs the admissibility of expert testimony. Under Daubert v. Merrell Dow Pharmaceuticals (1993), the trial judge serves as a gatekeeper with the responsibility of ensuring that expert testimony is both relevant and reliable before it reaches the jury. This replaced the earlier Frye 'general acceptance' test, which had required only that the scientific technique be generally accepted in the relevant scientific community.

The Daubert framework identifies several non-exclusive factors for assessing reliability: whether the theory or technique can be and has been tested, whether it has been subjected to peer review and publication, the known or potential error rate, the existence and maintenance of standards controlling the technique's operation, and whether the theory or technique has gained general acceptance in the relevant scientific community. In Kumho Tire Co. v. Carmichael (1999), the Court extended the Daubert gatekeeping function to all expert testimony — not just scientific testimony — including testimony based on technical or other specialized knowledge.

The 2000 amendment to FRE 702 codified the Daubert requirements, specifying that expert testimony is admissible if: (a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case. The 2023 amendment clarified that the proponent must demonstrate by a preponderance of the evidence that the expert's opinion reflects a reliable application of reliable principles and methods, overruling cases that had applied a more lenient standard.

## Elements

- The witness is qualified as an expert by knowledge, skill, experience, training, or education
- The expert's knowledge will help the trier of fact understand the evidence or determine a fact in issue (relevance/fit)
- The testimony is based on sufficient facts or data
- The testimony is the product of reliable principles and methods
- The expert has reliably applied the principles and methods to the facts of the case
- The proponent demonstrates admissibility by a preponderance of the evidence

## Key Case

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)

## Landmark Cases

| Name | Citation | Significance |
| --- | --- | --- |
| Daubert v. Merrell Dow Pharmaceuticals, Inc. | 509 U.S. 579 (1993) | Replaced the Frye general acceptance test with a multi-factor reliability analysis and assigned the trial judge a gatekeeping role over expert testimony. |
| General Electric Co. v. Joiner | 522 U.S. 136 (1997) | Held that appellate courts review a trial court's Daubert ruling under an abuse of discretion standard, giving trial judges significant latitude. |
| Kumho Tire Co. v. Carmichael | 526 U.S. 137 (1999) | Extended the Daubert gatekeeping function to all expert testimony, including technical and experiential expertise, not just scientific testimony. |
| Frye v. United States | 293 F. 1013 (D.C. Cir. 1923) | Established the pre-Daubert 'general acceptance' test, which some states still follow — expert testimony was admissible only if the underlying technique was generally accepted in the relevant scientific community. |

## Exam Tips

- Remember the Daubert trilogy: Daubert (reliability factors), Joiner (abuse of discretion standard of review), and Kumho Tire (applies to all experts, not just scientists).
- The Daubert factors are non-exclusive and flexible — not every factor applies in every case, especially for non-scientific expertise.
- Distinguish Daubert (federal standard) from Frye (still used in some states like California, New York, Illinois) — know which standard applies in the jurisdiction.
- Focus on the 'fit' requirement: even reliable methodology is inadmissible if it does not help the jury with the specific facts of the case.

## Common Mistakes

- Treating the Daubert factors as a rigid checklist — they are flexible, non-exclusive guideposts that the trial court may apply as appropriate to the type of expertise.
- Assuming Daubert applies only to scientific testimony — after Kumho Tire, it applies to all forms of expert testimony including technical and experience-based expertise.
- Forgetting that some states still use the Frye general acceptance test — Daubert is the federal standard but not universal.

## Mnemonic Or Memory Aid

Daubert's gatekeeping: the judge asks 'Is it Relevant and Reliable?' before the expert takes the stand. Think: R&R for experts.

## Related Rules

- lay-opinion-testimony-fre-701
- relevance-fre-401-403
- authentication-fre-901

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Source: [Expert Testimony (Daubert Standard) — CaseBriefly](https://casebriefly.com/legal-rules/expert-testimony-daubert-standard)