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The Admissibility Of Expert Testimony – A Special Report

Introduction

As products become increasingly complex and sophisticated and beyond the realm of “common knowledge,” products liability litigation has become correspondingly more complex.   As a result, the use of expert witnesses has become a central feature in the prosecution and defense of products liability cases.  This is true not only because lawyers need help in presenting technically complex cases, but more importantly because juries need help understanding the evidence and determining the facts in issue.  Consequently, expert testimony is required

Where . . . the ordinary layman cannot reasonably possess well-founded knowledge of the matter and could only indulge in speculation in making a finding, there must be expert testimony, based upon an adequate factual foundation that the thing alleged to have caused the result not only might have caused it but in fact did cause it.¹

At the same time that the importance of experts has increased, judicial scrutiny of the admissibility of expert testimony has been heightened.    Two recent federal court cases, Unrein and Fireman’s Fund (discussed below), highlight just how acute and potentially dispositive such judicial scrutiny has become.

An expert must not only be qualified to testify regarding the particular product at issue, but the expert must also be able to withstand a witness qualification hearing, a so-called “Daubert challenge” or “Frye-Mack challenge”, depending on where the case is venued.  In Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 589 (1993), the United States Supreme Court rejected the Frye test for federal courts, although the Minnesota Supreme Court in Goeb v. Tharaldson, 615 N.W.2d 800, 814 (Minn. 2000), rejected the Daubert test and decided that Minnesota continues to adhere to the Frye-Mack standards. 

Minnesota Standards for Expert Evidence

The Minnesota Supreme Court set the standards for the admission of scientific evidence in the Frye-Mack line of cases.²According to the Frye-Mack standard:

Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define.  Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

Frye v. United States, 293 F. 1013, 1014 (D.C. Ct. App. 1923). The admissibility of expert or scientific evidence under Frye-Mack therefore turns on whether the evidence relied on was “generally accepted” in the relevant scientific community; i.e., admissible scientific evidence must be (1) generally accepted and (2) reliable.  The evidence must also satisfy the requirements of Minn. R. Evid. 402 and 702 that it be relevant and helpful to the trier of fact.  State v. Nystrom, 596 N.W.2d 256, 259 (Minn. 1999).

The Minnesota Supreme Court affirmed Frye-Mack as the controlling standard in Goeb v. Tharaldson, 615 N.W.2d 800, 814 (Minn. 2000).  Members of the Goeb family became ill soon after they moved into a house that had been treated with insecticides. The Goebs sued the pesticide applicator, Tharaldson, and the manufacturer of the pesticide, Dow.  Dow successfully moved to exclude the testimony of two of Goeb’s expert witnesses on the grounds they had failed to follow proper methodology in determining that Goeb’s exposure to the pesticide had caused their health problems.  The Minnesota Supreme Court affirmed summary judgment against the plaintiffs.  In so doing, the court rejected  Daubert on several grounds, including that the “gatekeeper” role requires judges to be “amateur scientists,” whereas Frye-Mack ensures that those most qualified to assess the scientific validity of a scientific method (i.e., the relevant scientific community), has the “determinative voice” in the admissibility of expert testimony in Minnesota.

The Federal Standards for Expert Evidence

Plaintiffs in Daubert were two minor children and their parents. The mother ingested Bendectin during pregnancy and subsequently delivered two severely deformed children. Plaintiffs alleged that the Bendectin was responsible for the children’s birth defects. Merrell Dow’s expert concluded that there was no known correlation between in-utero Bendectin exposure and birth defects, and Merrell Dow moved for summary judgment. The trial court granted Merrell Dow’s motion and the court of appeals affirmed citing the Frye standard and holding that expert testimony was inadmissible unless derivative of a generally accepted scientific technique.

The United States Supreme Court reversed.  The Court held that the Federal Rules of Evidence superseded Frye and “wiped the slate clean.” Fed. R. Evid. 702 specifically addresses the issue of expert testimony and does not incorporate a general acceptance standard:

If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or 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.

The requirement that proffered expert testimony “assist the trier of fact to understand the evidence or determine a fact in issue” is a fundamental requirement of relevance.  The trial judge therefore is a “gatekeeper” who must screen the proposed expert evidence to ensure that “scientific testimony or evidence is not only relevant, but reliable.” The Daubert court identified the following factors that a court may consider in determining whether expert testimony consists of scientific knowledge that will assist the trier of fact:

• Can the expert’s method and technique be tested and reproduced?
• Has the expert’s theory or technique been published and subjected to peer review?What is the known or potential rate of error of the theory?
• Has the theory been generally accepted within the relevant scientific community?

Additional factors identified in Daubert can include whether the expertise was developed for litigation and whether the proposed expert has sufficiently connected the proposed testimony to the facts of the case. The Daubert court did not intend the list to be exhaustive and there is no single factor or requirement of admissibility that is dispositive, so long as the proposed expert testimony shows that the expert’s testimony is reliable and relevant. The purpose of the gatekeeping function of the court under Daubert is to ensure that expert testimony, that by definition concerns subjects beyond a jury’s ordinary knowledge, is both relevant to the issue before the court and can be relied upon by a jury to resolve questions of fact.

There have been several recent cases applying the standards of admissibility of expert testimony, two of which are discussed below to show how the courts deal with this difficult and potentially dispositive evidentiary issue.

²See Frye v. United States, 293 F. 1013 (D.C.Cir. 1923), and State v. Mack, 292 N.W.2d 764, 768-69, 772 (Minn.1980).