Presenting effective expert witness testimony requires more than finding someone who can arrive at the correct conclusions; you must communicate those conclusions in a convincing way. The rules of evidence and procedure can create disadvantages for unfamiliar experts and prevent them from being persuasive.
The goal of this three-part blog is to help attorneys communicate the constraints imposed on witnesses within the litigation setting, and to suggest ways for effectively communicating at deposition and trial, so that the expert can be a more persuasive witness. The first step is to guide the expert in forming opinions that will be clear, relevant, and defensible.
Crafting opinions with the jury in mind
Start by reminding the expert that the ultimate audience will be the jury. They should draft their opinions from the perspective of the jury members who will receive the testimony or report as one part of a larger story. This will help them put their opinions in context with the other evidence, and will also help them explain their opinions logically, starting with a broad view and going to a more detailed explanation. If the opinions will be used to support or defend a summary judgment motion, let the expert know how they can state their conclusions so they are consistent with the appropriate legal standard and help them understand how that legal standard will apply in the context of each case.
Request a verbal discussion of preliminary findings before your expert finalizes their opinions in any written format. This creates better understanding between you and the expert on important issues. If the preliminary findings are unfavorable, the expert can remain a consulting expert, as opposed to a testifying expert, and their opinions will not be discoverable. In state court, written reports are not required, and in fact, they can be excluded if opposed by the other side. In federal court, experts who are retained to provide testimony in a case must provide a written report pursuant to Federal Rule of Civil Procedure 26(a)(2)(B) containing all of their opinions, the facts they considered, any exhibits used, a list of all cases where they have testified at trial or in deposition in the last four years, and all publications in the last ten years.
Assumptions are normally required to fill gaps for unknown variables or disputed facts involved in the case. Tell the expert to make his/her assumptions as narrow as possible, based on a reasonable interpretation of the evidence. It is helpful to provide ranges, but it is not necessary to account for every extreme. Establish a range that is consistent with the evidence and does not weaken the expert’s level of confidence in their opinions.
To use a common example, think of a coefficient of friction, which must be determined for a skid mark analysis in an accident reconstruction. There are published data describing the coefficients of friction for various surfaces under various weather conditions. Establishing a coefficient for a particular case requires judgment on the part of the expert. You may expect their judgment will be tested on cross-examination. Let the expert know they should not fear making reasonable concessions. Juries normally have the ability to understand when the cross-examining lawyer has left the range of what is reasonable, and those types of admissions will not lessen the witness’s credibility.
Your expert’s testimony must be found sufficiently reliable by the trial court to be admissible. It is not necessary for him or her to testify as to any degree of certainty other than “more likely than not”, but the jury will appreciate knowing the degree of confidence they place on their own opinions. If appropriate, the confidence level can be stated in terms of percentages, or in general terms, such as highly confident. Make sure the expert stays within their comfort zone and does not stretch their opinions or exaggerate their confidence levels.
Tell the expert to request additional information if they feel that they have inadequate or inaccurate information. The opinions may be rejected by the jury if they determine the facts are different from those relied on by the expert. Opinions that are based on inadequate or incorrect information are likely to be considered speculation, and may be excluded by the judge or disbelieved by the jury. During the investigation and discovery phase of the case you should direct your expert to make their investigation as thorough as possible, and encourage them to think of avenues for obtaining information from all possible sources.
You may elect to provide your expert with partial information or make certain assumptions which may not be entirely consistent with all of the evidence, such as where some evidence is not admissible and you wish to keep from the jury, even though it might be otherwise relevant. When you force assumptions upon the expert, check those assumptions against the evidence and consider the effect that the assumptions will have on your expert’s opinions.
Stay tuned for Part Two: Defending Expert Opinions at Deposition.