The admissibility of expert testimony can be a game changer during trial. This is particularly true in federal court, which has its own rules and evidentiary standards. In federal court, an expert’s testimony can be challenged on a number of grounds. Typically, objections can be made during the pre-trial stage through motions in limine, particularly as they relate to expert disclosure obligations and written report requirements under Rule 26 of the Federal Rules of Civil Procedure and Rule 16 of the Federal Rules of Criminal Procedure. It is through these discovery requirements that an adversary is first put on notice of the expert’s identity and opinions and thus, can accordingly file any necessary motions to seek preclusion or limitation of the expert’s testimony. However, not all issues are handled via written motions in limine and oftentimes, objections need to be made in real time during trial, in front of the jury. In order to properly prepare and avoid unnecessary surprises at trial, it is incumbent that both the attorney and expert are aware of any potential objections that may be raised at trial.
1) The Expert is a Lay Witness
Because there are different standards of admissibility for experts and lay witnesses, an expert needs to be properly designated as such prior to providing any testimony.Under Rule 701 of the Federal Rules of Evidence, if a witness is not testifying as an expert, opinion testimony must be:
- a) rationally based on the witness’s perception
- b) helpful to clearly understanding the witness’s testimony or to determining a fact in issue
- c) not based on scientific, technical, or other specialized knowledge within the scope of Rule 702
In other words, a lay witness’ testimony needs to be based on first-hand knowledge or observation that is important to understanding a fact at issue, opposed to scientific knowledge on which an expert’s opinion is based. Because lay opinions must rely on facts personally observed, a witness offering lay opinion testimony must show that their opinion is based on personal knowledge, rationally related to the facts, and is helpful to the jury. Unlike a lay witness, an expert’s opinion need not be based on personal observation. But sometimes, a lay witness’ opinion is presented under the guise of an expert, or vice versa. Because the admissibility of expert testimony is, in many ways, more lenient than that of lay testimony, it is critical to object to any witness offering testimony beyond the scope of their designation. Likewise, if an expert is testifying to knowledge that more rightfully falls under the strictures of lay opinions, it is important to object accordingly.
2) The Expert is Not Sufficiently Qualified to Pass the Voir Dire Process
The purpose of the voir dire process is to establish the expert’s qualifications before the jury. At the beginning of an expert’s direct examination, counsel typically questions the witness about their educational background, work experience, training, and any other factor that goes to his qualifications within his specific field. A witness should be qualified through “knowledge, skill, practical experience, training, education, or a combination of these factors” and most importantly, be competent in the subject matter at hand. After the preliminary inquiry is complete, opposing counsel has the opportunity to question the witness’ qualifications and object to the witness if necessary. While the exact objections raised are dependent upon the specific qualifications (or lack thereof) of the witness, the voir dire process presents opposing counsel their first opportunity to expose the weaknesses in the witness’ credentials before a jury.
3) An Unwaivable Conflict Exists
Conflicts of interest oftentimes arise when an expert has an ongoing duty of loyalty to the opposing party, such as being a former employee, consultant, or expert for the other side. Ideally, potential conflicts of interest are addressed prior to trial. However, it is possible that an expert’s past associations or affiliations are not fully disclosed until he is testifying. At which point, an objection on conflict grounds would be appropriate. In order to successfully object to an expert’s testimony on these grounds, the moving party needs to establish that the expert had a previous, confidential relationship with the adversary, that the party disclosed privileged information to the expert, and that there is a public interest in excluding the testimony.
Surprisingly, there is scant case law regarding expert disqualification, as it is often seen as a drastic last measure. Nonetheless, courts throughout the country generally follow a three-prong analysis when deciding whether an expert should be disqualified from testifying based on his previous relationship with the opposing party. The Court asks:
- Was it reasonable for the opposing party to believe a confidential relationship existed with the expert?;
- Was confidential or privileged information disclosed by the opposing party to the expert?; and
- What is the public interest in admitting (or excluding) the expert’s testimony?
Generally, an expert will not be disqualified if he was not retained or otherwise employed by the opposing party and/or not provided any confidential information relevant to the case. However, if a party feels that the adversary’s expert has any duty of loyalty to them due to a previous relationship, an objection should be duly raised to preserve the issue and potentially exclude the testimony.
4) The Expert’s Testimony Fails to Fulfill the Standards Set Forth in Daubert and Rule 702 of the Federal Rules of Evidence
Although admissibility challenges are typically handled during pre-trial motions, a number of objections may be raised during trial testimony concerning the reliability of the expert. Rule 702 of the Federal Rules of Evidence, which codified the standard set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), guides federal court analysis in determining admissibility of expert testimony. Rule 702 states that an expert’s opinion is admissible if:
- a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue
- b) the testimony is based on sufficient facts or data
- c) the testimony is the product of reliable principles and methods
- d) the expert has reliably applied the principles and methods to the facts of the case
Rule 702 focuses on the reliability of the expert’s methods, rather than the actual conclusions. Therefore, the main question when determining admissibility of an expert’s testimony is whether the witness based his conclusions on sufficient facts or data and is the product of reliable principles and methods applied to the facts of the case. Because experts need not disclose all of the information on which they rely, whether their opinions are reliably drawn may not always be readily apparent from pretrial notices. Thus, opposing counsel should inquire as to an expert’s methods and object on reliability grounds, if necessary.
5) The Expert’s Opinion is Not Based on Reasonable Information
As a continuation to Rule 702, Rule 703 of the Federal Rules of Evidence establishes the bases on which experts may form their opinions, and notably, allows experts to base their opinions on information that is inadmissible at trial.
As Rule 703 states:
“An expert may base an opinion on facts or data in the case that the expert has been made aware of or personally observed. If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject, they need not be admissible for the opinion to be admitted. But if the facts or data would otherwise be inadmissible, the proponent of the opinion may disclose them to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect.”
Under Rule 703, experts may base their opinions on inadmissible evidence so long as such information is reasonable to rely upon. In addition, the inadmissible evidence can only be disclosed to the jury if its helpful in aiding the jury’s understanding and its probative value substantially outweighs any prejudicial effect.
In other words, experts may rely on hearsay or other types of evidence inadmissible by the other rules of evidence and the Constitution. Experts may be permitted to disclose inadmissible evidence to the jury for the limited purpose of evaluating the expert’s testimony. However, whenever otherwise inadmissible evidence runs the risk of being presented to the jury, opposing counsel should tread carefully and object to anything that can create a prejudicial effect.
6) The Expert’s Testimony is Not Relevant or Unduly Prejudicial
Expert testimony, like all testimony in a trial, must be relevant otherwise an objection should be raised to exclude. Rule 401 of the Federal Rules of Evidence permits the introduction of relevant evidence—that is, evidence that “has any tendency to make a fact more or less probable than it would be without the evidence; and . . . is of consequence in determining the action.” As stated in Rule 402, “Irrelevant evidence is not admissible.” Even if evidence is relevant and admissible for a proper purpose, it may still be excluded at the Court’s discretion under Rule 403. Under Rule 403, “The court may exclude relevant evidence if its probative value is substantially outweighed by a danger of one or more of the following: unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.”
An expert’s testimony should be relevant to the issues at hand. If an expert is testifying to facts that have no bearing on the case, an objection should be raised. However, even if an expert’s testimony can be deemed relevant, the probative value still must outweigh any prejudicial effect or other adverse dangers that the testimony could cause.