## Facts

- Parents and minor children sued a drug manufacturer, alleging that prenatal ingestion of an anti-nausea drug caused serious birth defects.
- The manufacturer moved for summary judgment with expert testimony and scientific literature concluding the drug had not been shown to cause human birth defects.
- Plaintiffs offered multiple expert witnesses opining causation, relying on animal studies, chemical-structure analysis, and an unpublished reanalysis of epidemiological data.
- The federal district court excluded plaintiffs’ expert evidence under the Frye “general acceptance” test and granted summary judgment for the manufacturer.
- The Ninth Circuit affirmed, treating Frye’s general-acceptance requirement as controlling for scientific techniques.
- The Supreme Court granted review to determine the governing standard for admissibility of scientific expert testimony in federal court after adoption of the Federal Rules of Evidence.

## Issues

1. Whether the Frye “general acceptance” test governs admissibility of scientific expert testimony in federal courts after adoption of the Federal Rules of Evidence.
2. Whether Federal Rule of Evidence 702 requires a different admissibility analysis centered on reliability and relevance, with a trial-judge screening function.
3. What considerations may guide a trial court’s reliability assessment of scientific testimony under Rule 702.

## Decision

- The Court held that the Federal Rules of Evidence, not Frye, provide the standard for admitting scientific expert testimony in federal trials.
- Frye’s general-acceptance test was superseded by the Federal Rules.
- Rule 702 requires the trial judge to act as a gatekeeper, admitting scientific testimony only if it is sufficiently reliable and relevant to assist the trier of fact.
- The Court vacated the Ninth Circuit’s judgment and remanded for application of the Rule 702 framework.

## Legal Principles

- Scientific expert testimony is admissible under Rule 702 only if it reflects “scientific knowledge” (reliability) and will “assist the trier of fact” (relevance/fit).
- The trial judge must make a preliminary assessment under Rule 104(a) of whether the reasoning or methodology is scientifically valid and can be applied to the facts at issue.
- Reliability is a flexible inquiry focused on principles and methodology rather than the correctness of conclusions.
- Relevant reliability considerations may include:
  - 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 and the existence of standards controlling the technique’s operation.
  - General acceptance in the relevant scientific community (as a factor, not a prerequisite).
- Weak but admissible expert evidence is addressed through cross-examination, competing proof, and instructions on the burden of proof.

## Conclusion

The Court replaced Frye’s general-acceptance rule in federal court with a Rule 702 framework requiring trial judges to screen scientific expert testimony for methodological reliability and relevance to the disputed issues, and it remanded for reconsideration under that standard.


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