Disclosure Rules: When To Share An Opposing Expert Witness’ Report

Rule 26 (a) (2) of the Federal Rules of Civil Procedure calls for the mandatory disclosure of any expert witness either side “may use at trial to present evidence under Federal Rule of Evidence 702, 703, or 705.” FRE 702 addresses testimony by expert witnesses, FRE 703 addresses the foundation upon which an expert opinion is based, and FRE 705 deals with the disclosure of facts or data which underlies the opinion of the expert, as well as how an attorney might elicit such information on direct or cross examination.

In addition, Rule 26 (a) (2)(B) calls for the disclosure of a written report prepared and signed by the expert. The exception to this, of course, is when it is otherwise stipulated to or ordered by the court. But what is a lawyer to do with the opposing expert witness’ report? And when?

There are benefits and drawbacks to providing one’s own expert with the opposing expert’s report. Attorneys have different philosophies about how to approach this situation. Not surprisingly, many experts also have strong views about reviewing or not reviewing the opposing side’s written report before trial. In larger litigation, a single side may have more than one expert. All these factors beg the questions: Can expert reports be shared? Should they be? Below, we discuss some approaches for determining the best course of action for your particular case.

Account For Bias

The issue of bias is one argument against disclosing the report of the other side’s expert prior to your expert’s independent examination of the evidence. While any expert worth their salt will tell you they are independent, and their opinions are soundly based on scientific principles, the fact remains that experts are human, and humans are subject to inherent biases. These biases can cut both ways.

Confirmation Bias

Confirmation bias occurs when a person sees what they expect to see. Consider, for example, the case of Brandon Mayfield. The Federal Bureau of Investigation erroneously matched Brandon Mayfield’s fingerprint to that of some bomb making materials found near a terrorist attack in Spain. In that case, both members of the FBI and an independent court expert declared the prints a “match” — a finding that was later proved false. According to the American Bar Association, the error was partially attributed to confirmation bias.

Confirmation Bias Study

To explore the issue of confirmation bias, Itiel E. Dror and others set up an experiment. The designers of the experiment selected five fingerprint examiners who had not seen the Mayfield prints. They provided the examiners with a questioned print, which they told the expert was from the terrorist attack. They also provided examiners with a set of prints purportedly from Mayfield. Finally, the experts in the experiment were asked if they saw a match.

Of course, by this point, every fingerprint examiner on the planet knew the case involved only a close non-match, not an actual match. Unbeknownst to the examiners, the prints were not actually from the Mayfield case. Rather, in each instance, the prints were from the examiners’ own case files, which the examiners had previously declared were, in fact, matches. The results were astonishing. Three of the five examiners declared the prints did not match – in direct contradiction to their previous findings. One examiner declared there was insufficient information and found the prints “inconclusive.” Only one examiner stuck with his original determination of an actual match. This experiment illustrates the point – extraneous information can bias a person in their decision making.

Bias may occur not only based on the contents of the report, but also the author of the report. If the opposing expert is respected in the community, that may have some influence on your expert when evaluating the report. Similarly, if your expert views the opposing expert unfavorably, that could bias their judgment. On the other hand, there is science to consider.

Use Science To Your Advantage

Science is both reproducible and verifiable. Whether or not food is contaminated with e coli, or a product is inherently dangerous based on a design flaw, or someone has a broken jaw are topics upon which we might expect reasonable experts to agree. Consequently, what is the harm in presenting your expert with another expert’s opinion?

One benefit to asking your expert to review another expert’s work is the opportunity to review that expert’s methodology. When an expert draws a conclusion and writes a report, they typically indicate what evidence they reviewed when coming to their conclusion. An expert who reviewed more or less data than your expert may come to a different conclusion. Thus, your expert may modify their opinion upon learning additional information. As unpleasant as that could be pretrial, it will not be nearly as unpleasant as experiencing it in real-time while your expert is being cross examined on the witness stand with the additional information.

Along the same lines, if it becomes evident the other side’s expert did not include a certain piece of information your expert found relevant, your expert can flag that for you. This gives you the opportunity to follow up on this point during depositions. Thus, your case stands to gain several benefits by simply exposing your expert to the opposing expert’s report.

Consider a Blended Approach

At the end of the day, every attorney must make strategic decisions that comply with local laws and rules as well as any special instructions provided by the court in each case. However, in some instances, a hybrid approach might be best. Consider, for example, first asking an expert for their opinion based on the facts and evidence. When the expert issues a preliminary opinion, (and only then) ask them to consider the opposing side’s expert’s opinion.

A word of caution, however. Experts are not circus monkeys. They do not appreciate “stunts” by lawyers. If you decide your client is best served by what experts refer to as “sequential unmasking,” there is nothing wrong with this approach. Simply refrain from doing so in an existential vacuum. Instead, be upfront with your expert from the get-go.

Experts have a fundamental understanding of how lawsuits work. They are aware there may very well be an expert on the other side who will render a different opinion. Speak with your expert about your desire to obtain their unbiased view as a starting point. Then, explain your desire to have them assist you in understanding why another expert came to a different conclusion.

Consider this: an expert who refuses to approach the problem this way when asked up front certainly isn’t going to do so if the approach is sprung on them without warning. Furthermore, an expert who is unwilling to consider the opposing expert’s position and determine areas of disagreement probably isn’t an expert you want to work with anyway.