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Daubert v. Merrell Dow Pharmaceuticals, 509 US 579 (1993) stated new rules for how a court determines whether to let experts testify. Daubert requires a pre-trial hearing where the trial judge decides whether to let an expert testify.

The Case

Petitioners were two minor children born with serious birth defects. They and their parents (“Plaintiffs”) sued Merrell Dow Pharmecuticals (“drug company”), alleging that the birth defects had been caused by the mothers' use of Bendectin, a prescription anti nausea drug. Drug company removed the suits to federal court on diversity grounds.

(“Diversity” means that all the plaintiffs reside in a different state than the defendant. It is a ground for federal jurisdiction. The theory is that an out of state corporation cannot get a fair trial in California state court, the defendant can move the case to federal court. As a matter of strategy, defendants prefer the federal courts because they tend to be more conservative. And, historically, drug companies have really taken a pounding in California state courts.)

Once in federal court, the drug company filed a motion for summary judgment. A motion for summary judgment is a brief with some evidence attached, arguing that there is no point in having a trial. The drug company contended that Bendectin does not cause birth defects, and that there was no reliable scientific evidence that it did. Plaintiffs conceded that none of the 30 existing human trials had demonstrated that Benedictin was a teratogen, but responded with affidavits by eight (8) experts. Based on in vivo studies, animal studies, structural analysis of the chemical to compare it with known teratogens, and re-analysis of previously published epidemiological studies, Plaintiffs’ experts were willing to testify that Plaintiff’s birth defects were caused by the drug.

The trial court ruled for the drug company. The court threw out Plaintiff’s evidence because the epidemiological re-analysis had not been published or subject to peer review, and the other studies were insufficient, by themselves, to merit going to trial.

The federal Circuit Court of Appeals for the Ninth Circuit affirmed the district court, based on the widely accepted "Frye" test for expert testimony. See Frye v. United States, 54 App. D.C. 46, 47, 293 F. 1013, 1014 (1923).

Under Frye, expert opinion based on a scientific technique was inadmissible unless the technique is "generally accepted" as reliable in the relevant scientific community. 951 F. 2d, at 1129-1130. Under this test, lack of a published paper doomed Plaintiff’s expert’s testimony.

The Supreme Court accepted the case to resolve a conflict among the lower courts about the continuted viability of the Frye test.

The holding

The Frye test no longer states the rules for admitting expert testimony. Frye has been supplanted by the Federal Rules of Evidence. Under Rule 702, “general acceptance” is only one factor among many in determining whether an expert’s opinion is reliable. The trial court put too much emphasis on “general acceptance” and must be reversed. Result: Plaintiffs got another chance to make their case.

The reasoning

The Rules of Evidence determine whether expert testimony should be admitted:

If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education may testify thereto in the form of an opinion or otherwise.

Fed. R. Evid. 702.

("trier of fact" means a jury, or in a case tried without a jury, the judge, to the extent that jury or judge weighs the credibility of the witness and decides fact issues).

In practice, determining whether expert testimony “will assist the trier of fact” is a complicated question. Faced with a proffer of expert testimony under Rule 702, the trial judge must assess whether the testimony's underlying reasoning or methodology is scientifically valid and relevant, that it, can properly can be applied to the facts at issue.

In short (a) is the proposed testimony reliable? and (b) is it relevant?

The Daubert case also gives a non-exclusive list of factors which may be considered in determining whethe a scientific opinion is “reliable”

  • whether the theories and techniques employed by the scientific expert have been tested;
  • whether they have been subjected to peer review and publication;
  • whether the techniques employed by the expert have a known error rate;
  • whether they are subject to standards governing their application; and
  • whether the theories and techniques employed by the expert enjoy widespread acceptance.

Thus, under Daubert, the “general acceptance” or Frye test becomes one factor among many to consider. As the Court has confirmed in later cases, these factors are not “holy writ”, but were intended to be helpful in ascertaining “reliability”. In some areas, where expertise is developed through experience, not through scientific processes, some of the factors are not useful at all.

While the Supreme Court does not have jurisdiction over epistemological theory, it does seem to adopt Karl Popper’s principle of “falsification” as a legal principle. See The Logic of Scientific Discovery, (London, Hutchinson, 1959). The majority opinion asserts that the “criterion of the scientific status of a theory is its falsifiability, or refutability, or testability”. This should not be taken very seriously, though.

In fact, judges don’t decide whether science is reliable or “junk science”. In the court room, cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof, rather than wholesale exclusion under an uncompromising "general acceptance" standard, is the appropriate means by which evidence based on valid principles may be challenged. Screening by the trial judge, on occasion, will prevent the jury from hearing about authentic scientific breakthroughs. This is simply a consequence of the fact that the Rules of Evidence are not designed to seek cosmic understanding but, rather, to resolve legal disputes.

And now for something we hope you’ll really like ...

The Daubert Worldview

Prolegomenon: A Pronunciation Gazetteer

Peter Nordberg, a Pennsylvania lawyer, has a hilarious website on Daubert. It’s jam packed with useful tactical ideas for lawyers, and even a Daubert forum. Highly recommended. Here's a sample:

Q: Before we get to what it all means, how is "Daubert" pronounced?

A: "Dow-burt."

Q: How do you know?

A: From published, peer-reviewed literature authored by a duly licensed attorney who developed his views in the regular course of his professional duties. See Michael H. Gottesman, Admissibility of Expert Testimony After Daubert: The "Prestige" Factor, 43 Emory L.J. 867, 867 (1994).

Q: What makes Gottesman an expert on this subject?

A: He represented Jason Daubert before the Supreme Court and listened to his client pronounce the name.

Q: So Gottesman's opinion on the correct pronunciation was developed for litigation purposes?

A: Yes.

Q: Is "dow-burt" the generally accepted pronunciation?

A: Not universally so. Many lawyers and judges say "dough-bear."

Q: Well, what about the methods Gottesman used to arrive at his conclusion? Is listening to the client a prevalent methodology in the legal field?

A: To a point.

Q: So did Gottesman take any courses on listening to the client during law school?

A: Almost certainly not.

Q: Has the technique of listening to the client been tested?

A: Informally.

Q: Does it have a known error rate?

A: The error rate is thought to be fairly high.

Q: Has Gottesman been consistent, at least, in the position he has taken on the proper pronunciation?

A: No. When he was arguing the case before the Supreme Court, he pronounced the name "dough-bear."

Q: Why?

A: The Justices seemed to prefer that pronunciation.

© 2001-2002 Peter Nordberg (www.DaubertOnTheWeb.com).


  • Void where prohibited. (My favorite!)
  • IANYL (Yeah, sure, I am a lawyer, but: I Am Not Your Lawyer).
  • YMMV
  • See a doctor before commencing any program of litigation
  • See a lawyer to assess any IRL problem. Good legal advice can't be given without knowing the facts of your case, the law in your jurisdiction and whether your check has cleared.
  • WWJD? Jesus would settle. I have it on good authority (Matthew 5:25).

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