The Standard Governing Expert Witness Testimony

Expert witnesses are routinely utilized in civil court cases to help one side obtain a favorable outcome. Their testimony is often the key factor in winning, or losing, the case. An expert is a person with “scientific, technical, or other specialized knowledge."

For many years the “Frye” case was the standard used to determine that evidence could be admitted in court only if the thing from which the deduction is made is sufficiently established to have gained general acceptance in the particular field in which it belongs (Frye v. United States, 293 F. 1013 [D.C. Cir. 1923] ).

However, in the 1993 Daubert case (Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 ), the U.S. Supreme Court ruled that the standard for admitting expert testimony in federal courts was based on the enactment of the Federal Rules of Evidence (1975) which overturned the Frye standard. In effect, the Court established three new rules governing admission of expert testimony in court.

The first was scientific knowledge. This means that the testimony must be scientific in nature, and that the testimony must be grounded in "knowledge." Of course, science does not claim to know anything with absolute certainty; science "represents a process for proposing and refining theoretical explanations about the world that are subject to further testing and refinement." The "scientific knowledge" contemplated by Federal Rules of Evidence 702 had to be arrived at by the scientific method.

Second, the scientific knowledge must assist the trier of fact (jury or judge) in understanding the evidence or determining a fact in issue in the case. To be helpful to the trier of fact, there must be a "valid scientific connection to the pertinent inquiry as a prerequisite to admissibility." As an example, although it is within the purview of scientific knowledge, knowing whether the moon was full on a given night does not typically assist the trier of fact in knowing whether a person was sane when he or she committed a given act.

Third, the Rules expressly provided that the judge would make the threshold determination regarding whether certain scientific knowledge would indeed assist the trier of fact in the manner contemplated by Rule 702. This preliminary assessment can turn on whether something has been tested, whether an idea has been subjected to scientific peer review or published in scientific journals, the rate of error involved in the technique, and even general acceptance, among other things. It focuses on methodology and principles, not the ultimate conclusions generated.

["...Scientific conclusions are subject to perpetual revision. Law, on the other hand, must resolve disputes finally and quickly …"]

The Court stressed that the new standard under Rule 702 was rooted in the judicial process and intended to be distinct and separate from the search for scientific truth. "Scientific conclusions are subject to perpetual revision. Law, on the other hand, must resolve disputes finally and quickly. Rule 702 was intended to resolve legal disputes, and thus had to be interpreted in conjunction with other rules of evidence and with other legal means of ending those disputes. Cross examination within the adversary process is adequate to help legal decision makers arrive at efficient ends to disputes.

How does this affect expert witness testimony by non-scientific witnesses? The Supreme Court later ruled that the standard in Daubert could apply to merely technical evidence or specialized knowledge, provided the testimony of the expert was reliable.

Nelson Tucker of Process Service Network in California a qualified Expert Witness on service of process issues and has authored 3 books on the subject. Process Service Network can be found at http://www.processnet1.com/ or email at processnet@sbcglobal.net