4 Key Factors to Withstand a Daubert Challenge

expert witness testimony courtBy Anjelica Cappellino of The Expert Institute

Preparing for trial with an expert witness is not an easy task. It requires finding a qualified expert in the specific field, conducting analysis and studies that confirm the case theory, and organizing and strategizing testimony that will come across favorably to the trier of fact.

One of the most daunting roadblocks, however, is an adversary challenging the reliability of your expert’s testimony. A Daubert motion, named after the seminal Supreme Court case upon which the governing standard for expert testimony is based, is a specific type of motion in limine that seeks to exclude the testimony of an expert witness that used questionable methods or does not possess the requisite level of expertise. It is the party seeking to admit expert testimony, not the moving party, that bears the burden of proof to establish the admissibility of the testimony by a preponderance of the evidence. In deciding whether to admit the expert testimony, a judge will consider the enumerated factors outlined in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

Daubert held that Rule 702 of the Federal Rules of Evidence is the standard for admitting expert scientific testimony in a federal trial, superseding the previous standard set forth in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), which stated that expert opinion based on a scientific technique is inadmissible unless the technique is “generally accepted” as reliable in the relevant scientific community. While FRE 702 does not require that the evidence is “generally accepted” in the scientific community, Daubert noted that courts have a “gatekeeping responsibility” to ensure the evidence is reliable and relevant. Daubert set forth a non-exclusive checklist for trial courts to use in assessing the reliability of scientific expert testimony, and depending upon the particular circumstances of the particular case at issue, non-scientific testimony as well, as established by its progeny.

Specific Factors

The specific factors explicated by the Daubert Court are:

  1. Whether the expert’s technique or theory can be or has been tested—that is, whether the expert’s theory can be challenged in some objective sense, or whether it is instead simply a subjective, conclusory approach that cannot reasonably be assessed for reliability;
  2. Whether the technique or theory has been subject to peer review and publication;
  3. The known or potential rate of error of the technique or theory when applied and the existence and maintenance of standards and controls; and
  4. Whether the technique or theory has been generally accepted in the scientific community.

In order to overcome the challenge, it is vital to understand said factors so that they can be strategically used for the expert testimony’s survival.

Tested and Assessed for Reliability?

The takeaway point of the first Daubert factor – whether the technique or theory can be or has been tested – is that admissibility rests only on the expert’s principles and methodology, not the conclusions. The court’s gatekeeper function is intended to screen the expert, not to decide whether the expert presents the right answer, which is a task for the trier of fact. Experts need not identify themselves as correct but must only demonstrate by a preponderance of evidence that their opinion is reliable. While the “evidentiary requirement of reliability is lower than the merits standard of correctness… any step that renders the analysis unreliable… renders the expert’s testimony inadmissible.” Because the key focus is reliability, experts should highlight the methodology and reliability of their procedures, regardless of their conclusions.

Subject to Peer Review and Publication?

The Daubert Court held that the scrutiny of the scientific community would increase the likelihood of an expert’s methodological flaws being exposed. But whether the expert’s theory has been subject to peer review and publication is not, as Daubert describes, “a sine qua non of admissibility.” In rendering its opinion, the Court was careful to note that some theories are too particular, new, or limited to be published. In evaluating an expert’s reliability under this factor, it is important to recognize the limitations of peer reviewed publications, such as fact-checking failures, publisher bias, and outright fraud. In the absence of a formal publication, the peer review of an expert’s opinion can be shown in a broader sense, that is, whether the opinion has history within the scientific community.

Potential Rate of Error?

Assessing the potential rate of errors and the maintenance of any standards and controls is a factor associated more with scientific technique, such as the false positive rate of a drug test or the matching percentages of a DNA report. In plain language, however, this factor evaluates the expert’s likelihood of being wrong. Determining a numerical error rate might not always be possible, in which case, the expert should be prepared to offer reasons why alternative opinions or conclusions are deemed incorrect. Because Courts are less concerned with whether an expert’s assertions are actually correct, but rather, whether they are reliable, the point of this factor is to enumerate, but not necessarily strictly quantify, the likelihood that the expert is wrong.

Accepted in the Scientific Community?

Lastly, whether the expert’s opinion has been generally accepted in the scientific community is a revisit to the previous Frye standard. However, Daubert does not rely on general acceptance to establish reliability, but rather, uses the factor as a gauge. The Court notes that while widespread acceptance can be important in its ruling, a known technique that has only attracted minimal support can be a strike against admissibility. Therefore, a relatively new or less known theory in the scientific community may fare better before the courts than a well known, but not widely accepted opinion.

Thinking Outside the Factors

Arguably, the most important Daubert factor, however, is not in Daubert at all.

Daubert itself emphasized that the factors were not an exclusive and dispositive list, as not all of the specific factors can be applicable to every expert witness. In assessing reliability, Courts have acknowledged other considerations such as the “analytical gap” between the data and the expert’s opinion, See General Elec. Co. v. Joiner, 522 U.S. 136, 146 (1997), whether a medical expert considered other obvious causes of a health condition, See Claar v. Burlington N.R.R., 29 F.3d 499 (9th Cir. 1994), and whether an expert applies the same standard and “intellectual rigor” in one’s field as in the courtroom. See Kumho Tire Co. v. Carmichael, 119 S.Ct. 1167, 1176 (1999). Therefore, if an expert does not strictly satisfy the Daubert factors, there are other alternatives to proving the testimony is still otherwise reliable and relevant. After all, the original purpose of Daubert was to liberalize the use of expert testimony. So experts across the spectrum – from archaeology to zoology and everything in between – may display the reliability of their testimony in a number of ways particularized to their specific field.


Share this Post: