How Expert Evidence is Evaluated by the Courts
by Moderator on Feb.09, 2011, under Topics for discussion
Rule 702 of the US Federal Rules of Evidence, Testimony by Experts, states:
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.
In the 2000 Amendment, Committee Notes on Rules, it further states, in part:
Rule 702 has been amended in response to Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), and to the many cases applying Daubert, including Kumho Tire Co. v. Carmichael, 119 S.Ct. 1167 (1999). In Daubert the Court charged trial judges with the responsibility of acting as gatekeepers to exclude unreliable expert testimony, and the Court in Kumho clarified that this gatekeeper function applies to all expert testimony, not just testimony based in science. … The amendment affirms the trial court’s role as gatekeeper and provides some general standards that the trial court must use to assess the reliability and helpfulness of proffered expert testimony. Consistently with Kumho, the Rule as amended provides that all types of expert testimony present questions of admissibility for the trial court in deciding whether the evidence is reliable and helpful. Consequently, the admissibility of all expert testimony is governed by the principles of Rule 104(a). Under that Rule, the proponent has the burden of establishing that the pertinent admissibility requirements are met by a preponderance of the evidence.
These statements are the basis of how expert evidence is evaluated by the courts and the requirements experts must provide to assist judges to determine the admissibility of evidence. Of course, it places the onus on judges to be able to understand arcane scientific matters in order to issue their findings of admissibility.
Judges serve as “Gate Keepers” and decide which expert testimony jurors may consider. How can judges and for that matter lawyers, be better trained in science to perform their task?
February 11th, 2011 on 10:43 am
In states (like California), that retain the Frye test of general acceptance, the judge is not evaluating the “nuts and bolts” of the new scientific technique to determine its fundamental validity. Rather, the proponent of the evidence must demonstrate that the technique is generally accepted in the relevant scientific field. In other words, it is a survey of sorts, and the courtroom does not become a laboratory.
This approach has appeal, because how can one expect a non-scientist trial judge to competently evaluate the validity of a scientific technique in the limiting context of pretrial litigation, when outside experts have potentially felt it appropriate to conduct validation studies, debate in scientific journals, and present at conferences on a topic? The Frye general acceptance standard obviates the need for judges to become scientific experts themselves.
On the other hand, if a trial court cannot understand proposed scientific testimony (even if it finds it generally accepted), then how can we expect jurors to understand it to the extent that they can accord it the evidentiary weight it deserves? I think the answer lies in part in giving criminalists and other expert witnesses training in the commuication skills necessary to simplify (not oversimplify) complex topics so that a layperson juror can understand them. This is easier said than done, but scientists appearing in the courtroom have the special challenge of needing both scientific expertise and the rhetorical skill to educate non-scientists about their scientific fields, testing, and results.