Expert testimony is of increasing importance in litigation and can make or break a case. However, if an expert’s testimony is deemed inadmissible or is largely curtailed in scope, it can be rendered useless. Whether you are seeking to admit your own expert or arguing against the admissibility of your adversary’s, it is important to be mindful of the ways an expert’s testimony can be objected to or otherwise challenged.
Know the Governing Standard
Each jurisdiction has a different standard for expert admissibility but generally speaking, most states either follow some variation of the Daubert or Frye tests. In the D.C. Circuit case, Frye v. United States, 293 F. 1013 (D.C. Cir. 1923) the Court held that an expert opinion is admissible if the scientific technique on which the opinion is based is “generally accepted” as reliable in the relevant scientific community. Commonly referred to as the “general acceptance” test, a number of states follow this standard, which focuses on the consensus of the expert’s own community.
70 years later, the United States Supreme Court set forth a competing standard in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), which listed several factors that a court may consider when determining the admissibility of an expert. Aside from general acceptance within the scientific community, which Daubert includes as a factor, the Court also asks (1) whether the expert’s technique or theory can tested and 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; and (4) the existence and maintenance of standards and controls. Approximately 27 states use some version of the Daubert test with 9 states having fully adopted the standard. The Daubert standard is also utilized in federal court, codified in Rule 702 of the Federal Rules of Evidence.
Although there is no evidence that one standard is stricter than the other (several studies have been conducted but a consensus cannot be reached), it is nonetheless critical to know the standard within your practicing jurisdiction and tailor your arguments accordingly.
Motions In Limine
The battleground for expert admissibility typically begins well in advance of trial. Typically, parties are obligated to provide a disclosure notice if they intend to use an expert (in the federal context, this is governed by Rule 26 of the Federal Rules of Civil Procedure and Rule 16 of the Federal Rules of Criminal Procedure). Therefore, if you intend to object to the entirety (or a portion) of your opposing party’s expert, it is helpful to make those arguments via a motion in limine (a pre-trial motion requesting the exclusion of certain testimony or evidence). Although the entirety of the opposing expert’s testimony will not be disclosed to you at this stage, the notice requirement should provide you sufficient information on which any objections can be based. A motion in limine can challenge the reliability of the expert’s testimony or the expert’s qualifications as a whole from an inspection of their credentials.
Pre-trial motions are also an opportune time to bring to light any potential conflicts of interest that may exist that would disqualify the opposing expert. For example, if an expert previously worked for or testified on behalf of the plaintiff in another case, it would be deemed a conflict of interest for the expert to then testify as a defense witness. In these instances, conducting research into the opposing expert and their proposed testimony and then succinctly drafting a written argument can save time down the line at trial. It also avoids reliance on oral, spontaneous objections, which by their nature, will be less informative than a written motion.
Be Alert During Trial
During trial, it is important to object accordingly to any expert testimony that is improper or otherwise irrelevant. As an initial matter, opposing counsel does have the right to conduct a brief voir dire to establish the expert’s qualifications before the jury. This occurs before the expert’s direct examination and the questions are typically limited to educational background, training, or experience. Although the expert’s qualifications may have already been argued in a motion in limine, a voir dire can bring out additional information that may further support an objection to admissibility.
Once an expert passes the voir dire process and begins their direct examination, it does not mean the testimony is inimitable. Even an otherwise qualified expert may veer into areas that are beyond the permissible scope, which is why it is important to stay vigilant for potential objections during trial. Such impermissible areas would include topics that are not within the expert’s expertise or theories that are not sufficiently reliable. On the other end of the spectrum, an expert, by definition, is not a lay witness or fact witness. Therefore, their testimony should be limited to matters for which the jury would not be capable of understanding without an expert’s help.
Lastly, an expert’s testimony (like all witness testimony) needs to be relevant to the facts at issue. In matters of scientific testimony, it is easy to become confused as to what is or is not relevant to the disputed facts. However, timely objecting to irrelevant testimony can save precious trial time while also preventing the expert from appearing more knowledgeable in the eyes of the jury.
Overall, the potential for objections to expert testimony begin the moment the expert’s identity is disclosed and do not end until the expert is off the stand.