Flexible standards, deferential review: Daubert's legacy of confusion.

• Author: Welch, Cassandra H.

1. INTRODUCTION

   Expert evidence--particularly expert scientific evidence--has long been thought to require special treatment in the courtroom. (1) Concern about "junk science" and fear that jurors will be easily impressed by such evidence are two oft-cited reasons for giving special attention to expert testimony. (2) Addressing these concerns, the Supreme Court set the standard for the admissibility of expert testimony in the 1993 case of Daubert v. Merrell Dow Pharmaceuticals. (3) The holding of Daubert and two other cases, referred to as the "Daubert trilogy," (4) were later codified in Rule 702 of the Federal Rules of Evidence: (5)

   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, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case. (6) The exact standard for the admission of expert testimony remains uncertain, and because evidentiary decisions under Daubert are reviewed only for abuse of discretion, courts have had little opportunity to reconsider or redefine the standard of admissibility. (7)

   This Note argues that the flexible standard for admissibility of expert testimony and the abuse of discretion standard of review on appeal result in continued confusion about when expert testimony is reliable enough to be considered by the factfinder. Part II outlines the history of the Daubert trilogy. Part III describes the current application of Daubert, giving an example of how little guidance Daubert provides and elucidating the problems with the flexible approach and the deferential standard of appellate review. Part IV examines the practical application of the Daubert standards by judges across circuits, the debate on whether Daubert is liberal or conservative, and the confusion among scholars and jurists following the opinion. It also explores judges" confusion and their perceptions of their role as gatekeeper. Part V addresses the goals of both the Federal Rules of Evidence and Daubert and the ways the current approach to the admissibility of expert testimony fails to achieve those goals. Finally, this Note concludes that a more conservative standard is needed to provide guidance to judges when expert testimony is at issue and that more appellate oversight is necessary to ensure that expert testimony is appropriately reviewed and admitted or excluded.

2. THE DEVELOPMENT OF CURRENT STANDARDS: FROM FRYE TO THE DAUBERT TRILOGY

   For seventy years following the decision of the Court of Appeals for the District of Columbia in Frye v. United States, (8) expert testimony based upon a scientific principle was inadmissible unless the principle had gained "general acceptance" in its field. (9) In Frye, the defense had sought to introduce an expert to testify to the results of a systolic blood pressure deception test--the precursor of the modern polygraph--to which the defendant had been subjected. (10) Citing no previous cases, the court held that the systolic blood pressure deception test had not achieved general acceptance within the fields of physiology and psychology and that expert testimony deduced from the test was therefore inadmissible. (11)

   In the years after Frye, "sharp divisions" developed among the circuits about the proper standard for the admission of expert testimony, with some courts applying the Frye test and others rejecting it. The Supreme Court resolved the conflict in Daubert v. Merrell Dow Pharmaceuticals, Inc. (12) In Daubert, plaintiffs Jason Daubert and Eric Schuller, born with serious birth defects, had alleged that these defects were a result of their mothers' ingestion of the drug Bendectin and sought to introduce expert testimony that Bendectin could cause such defects. (13) Applying the Frye test, the district court found that the scientific principles upon which the plaintiffs' expert testimony was based were not generally accepted. The court therefore granted the defendant's motion for summary judgment, which had asserted that the plaintiffs could not produce admissible evidence that Bendectin caused their birth defects, (14) and the Court of Appeals for the Ninth Circuit affirmed. (15)

   The Supreme Court disagreed, noting that Frye predated the Federal Rules of Evidence and thus was superseded by them. (16) Furthermore, nothing in the drafting history of the rules suggested that general acceptance was intended to be a prerequisite for the admission of expert testimony, and requiring general acceptance would go against the "liberal thrust" of the Rules and their "general approach of relaxing the traditional barriers to 'opinion' testimony." (17) Frye's rule was not assimilated in the Federal Rules; instead, it was incompatible with them and Frye's general acceptance standard should not be applied in federal courts. (18)

   Although it rejected Frye's limits on the admissibility of expert testimony, the Court did not leave in its place a standard-less regime. (19) Instead, the Court directed the trial judge to apply a two-prong test for admissibility: the evidentiary proffer must be both relevant and reliable. (20) First, to be admissible, the evidence must qualify as relevant under Rule 702, which states that such evidence must "assist the trier of fact to understand the evidence or to determine a fact at issue." (21) Thus, as with any other type of evidence, the relevance requirement will cause expert scientific evidence to be admissible for some purposes but not for others. Second, the evidentiary proffer must be "reliable"; the Court listed several factors to assist the trial judge in determining whether the evidence exhibits sufficient indicia of reliability to be admissible. (22) The first and most important factor to determine reliability is whether the scientific principle sought to be adduced is testable. (23) Subsidiary factors include publication and peer review; (24) the "known or potential error rate"; (25) and general acceptance. (26) The overriding principle enunciated by the Court is that the inquiry should be flexible and focused on scientific methodology rather than the substantive scientific conclusions advocated by the expert. (27) The Court vacated and remanded the judgment of the Ninth Circuit because its decision rested almost entirely on general acceptance. (28)

   In General Electric Co. v. Joiner, the Court addressed the proper standard of review for an appellate court reviewing a trial court's decision on the admissibility of expert testimony. (29) Plaintiff Robert Joiner was a city electrician and worked with electrical transformers that were cooled by a fluid--with which Joiner frequently came in contact-containing polychlorinated biphenyls (PCBs), which "are widely considered to be hazardous to human health." (30) When he was diagnosed with lung cancer, Joiner sued the manufacturers of the transformers and PCBs, alleging that, although he had been a smoker, it was the PCBs that had "promoted" his cancer, and proffering scientific experts to support this allegation. (31) The court granted summary judgment for the defense, stating that the testimony of the plaintiff's experts "did not rise above 'subjective belief or unsupported speculation." (32) The Court of Appeals for the Eleventh Circuit reversed, noting that the Federal Rules show a preference for admissibility and concluding that appellate courts must apply a very stringent standard of review when expert testimony is excluded. (33)

   The Supreme Court reversed the judgment of the Court of Appeals, holding that evidentiary rulings are to be reviewed by appellate courts under an abuse of discretion standard. (34) Although the Eleventh Circuit suggested that Daubert had altered that standard, the Court found that Daubert did not address the standard of review at all. (35) The Court noted that although Daubert provided a more liberal application of the Federal Rules, trial judges' gatekeeping role was unaltered. (36) Therefore, no distinction should be made between an exclusion of expert testimony and an inclusion of expert testimony on review by an appellate court, and the applicable standard for both is abuse of discretion. (37) The Court held that the district court did not abuse its discretion. (38)

   In Kumho Tire Co. v. Carmichael, the Court further clarified the extent to which the Daubert standard applies to proffers of evidence under Rule 702. (39) The plaintiffs, who brought a products liability suit after a tire blowout on their minivan resulted in a fatal accident, sought to introduce the testimony of an expert who was to testify that the tire's defect caused the blowout, relying, in part, on visual and tactile inspection rather than scientific methodology. (40) The district court reviewed the expert's methodology, which was described as technical, and applied the Daubert factors. (41) Even after considering the expert's testimony under a "more flexible" interpretation of Daubert, the district court found that the expert's testimony was not reliable. (42) The Eleventh Circuit reversed and remanded, stating that Daubert applies only to scientific knowledge. (43) The Supreme Court granted certiorari to clarify the confusion among the lower courts about whether Daubert applies to nonscientific expert testimony. (44)

   The Supreme Court held that a judge's basic gatekeeping function applies to all expert testimony. (45) The Court noted that the language of Rule 702 and Daubert suggests that there should be no distinction between scientific knowledge and other knowledge. (46) Furthermore, the Court could not identify a convincing reason to draw such a distinction, as the judge's role as...