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The Value Of A Rebuttal Expert Witness

Expert witnesses are frequently used by attorneys to establish essential elements of their case in chief. Yet an expert’s testimony can be invaluable at other points in the trial as well, such as during rebuttal.

Dani Alexis Ryskamp, J.D.

Written by
— Updated on December 8, 2021

The Value Of A Rebuttal Expert Witness

Here, we look at the role rebuttal expert witnesses play in the trial process. We’ll explore how these witnesses are used, why attorneys use them, and the types of cases in which a rebuttal expert witness is most likely to appear.

Why Choose a Rebuttal Expert Witness?

Rebuttal expert witnesses are most commonly used in cases in which one side must offer an alternative explanation for the opposing party’s view of the facts in order to persuade the jury to take their view. Often, the need for them appears during discovery: One party discloses their expert, the opposing party makes a Daubert or summary judgment motion arguing that the expert is deficient, and the first party seeks an additional expert disclosure – aka a “rebuttal” expert.

Without the help of the rebuttal expert, one side may be limited merely to saying “no, you’re wrong,” without being able to offer any explanation as to why the opposing party is wrong or what alternate situation might explain the facts instead.

Rebuttal experts are often the subject of disclosure disputes: can the rebuttal expert be allowed to testify even if they weren’t disclosed before the deadline? While the decision lies in the hands of the judge in each particular case, the rule governing that decision is relatively simple: a rebuttal witness’s testimony cannot be offered as part of the case in chief, and it cannot be offered solely to support the testimony of an initial expert witness who is part of the case in chief.

How to Deploy a Rebuttal Expert Witness

Rebuttal expert witness issues commonly appear in personal injury cases and similar civil claims in which the expert’s opinions are at least partially subjective – often, because they’re based on observation and judgment rather than on quantitative analysis.

In most trials, the window in which to submit rebuttal expert witness testimony is very narrow, which can make it tricky for attorneys who disclose their expert solely as a “rebuttal” expert. However, several courts have permitted an expert to testify on rebuttal when that expert was originally disclosed as an initial expert witness.

For instance, in Nunez v. Harper (2014), the defendant in a car accident claim disclosed their medical expert within the deadline for rebuttal expert disclosure. The plaintiff moved to exclude, arguing that the expert was not a proper rebuttal expert. The court concluded that the rebuttal expert’s report was that of an initial expert, since it set forth a number of theories not covered by the plaintiff’s expert, and that the defendant should have seen the need to disclose the expert as an initial expert, not only as a rebuttal expert.

Nonetheless, the court decided that excluding the witness was improper, since the plaintiff still had time to depose the expert witness.

A change in circumstances may also justify using an initial expert witness as a rebuttal witness, even after the deadline for disclosing a rebuttal witness has expired. In Feador v. State Farm Ins. Mut. Auto. Co. (2014), another car accident case, the defendant disclosed two initial experts, one of whom was a medical doctor testifying as a medical expert. After further discovery and after the rebuttal deadline expired, the plaintiff designated its own rebuttal expert. Both parties motioned to strike the designation or to modify the discovery scheduling in light of the plaintiff’s disclosure.

The court concluded that because the additional discovery had caused a change to the defendant’s expert’s opinions, and because the timing of that change had come so close to the rebuttal deadline, the plaintiff could designate a rebuttal expert after the deadline passed, because the plaintiff couldn’t have foreseen the change in circumstances.

Finally, if being allowed to rely on a rebuttal expert seems particularly difficult, seeking leave to make a late disclosure or to supplement the initial expert’s opinion also provide options for building the case, rather than being left simply saying, “No, you’re wrong.”

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