Four-Factor Test to Determine Expert Testimony Reliability

The Daubert standard main purpose is to determine the scientific validity of the offered expert testimony, giving defense attorneys more ways in which to attack such testimony. Thus, judges as “gatekeepers” must use four factors to determine whether the theories and methodologies of the offered expert testimony are reliable, taking under consideration:

whether the expert’s theory or technique can, or has been, tested;
whether the theory or technique has been subjected to peer review and publication;
the known or potential rate of error of the technique or theory for a particular scientific technique; and
whether the theory or technique is generally accepted in the relevant scientific community.

Judges must use four factors to determine whether the theories and methodologies of expert testimony are reliable

Although, all of the above factors remain relevant to the determination of the reliability of expert testimony, other factors may also be relevant; so far no factor alone is necessarily dispositive of the reliability of a particular expert witness’s testimony. See Kumho Tire Co.

Courts have found other factors relevant in assessing whether the expert’s testimony is sufficiently reliable in order to be considered by the jury. These other relevant factors are:

Whether expert’s testimony is about matters growing naturally and directly out of research that he has conducted independently of the litigation;
Whether the expert has inexcusably extended from an accepted method to an speculative conclusion where the court may conclude that is too great an analytical gap between the data and the given opinion;
Whether the expert has effectively considered for apparent alternative explanations testimony excluded where the expert failed to review other evident causes for the plaintiff’s condition;
Whether the expert is being as careful as he would be in his regular professional work outside his paid litigation consulting; and
Whether the expert’s field of expertise is known to reach reliable results for the type of expert opinion given.

Likewise, the Daubert standard reflects Federal Rule of Evidence 702 and requires a court to contemplate three underlying requirements when assessing reliability of scientific expert testimony. The factors to consider by the Daubert court are:

whether the expert’s testimony is based upon sufficient facts or data;
the expert’s testimony is the product of reliable theory and methods; and
the expert applied the above theory and methods reliably to the specific facts of the case.

Also, under Kumho Tire Co., these three requirements must be interpreted and applied in accordance with the four-part Daubert test, which facilitates to assess the reliability and helpfulness of proffered expert testimony.

This new standard has widened the reach of expert’s evidence standard by exposing pure opinion testimony to its analysis. It also applies to new-and-novel or tried-and-true techniques. All are subject to analysis under the new standard. Further, the new standard applies to scientific and technical testimony and other specialized knowledge, including other experts who are not scientists since Rule 702 does not evaluate academic training over demonstrated practical experience because all that is needed is ordinary skill in the matter at issue. See also Kumho Tire Co.

Therefore, the Daubert standard gives attorneys the chance to more carefully analyze expert testimony since it will avoid decisions based upon “junk science” and show more credible expert testimony. Accordingly, attorneys should consider challenging the admissibility of scientific expert witness testimony especially in products liability cases based on challenges frequently associated with Daubert, such as testability of the theory, peer review, quantitative analysis, and error rate.

Consolidated Consultants Co.