Avoiding Cumulative Expert Witness Testimony in Class Action Lawsuits

Edward Maggio, J.D., M.S.

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— Updated on March 2, 2021

Avoiding Cumulative Expert Witness Testimony in Class Action Lawsuits

To win a class action matter, a lawyer may use multiple experts in order to successfully drive home their client’s argument. It is a common strategy that more experts testifying to the liability of the defendant should result in an easier win for the plaintiff. However, it is very easy for a lawyer to overlook that hiring multiple experts may, in fact, be detrimental to their overall case. What should be a roadmap to success can actually result in a courtroom loss.

Concerns for the Cumulative Approach

Courts have expressed their concerns that the use of multiple experts could lead to an excessive cumulative approach. In simple terms, the cumulative approach implies that several experts in a case repeatedly testify to the same information and subject matter. Although it may seem like reiterating key points would strengthen your argument, the use of experts that testify on the same topic only leads to potential irrelevance.

Even worse, the opposition can object that a cumulative approach creates unfair prejudice. When one side presents three or more experts compared to the opposition, the risk increases that the jury will consider the party with the most experts more truthful or factually correct. In other words, just on perception, jurors will pick the side of legal conflict which brought more experts to the courtroom.

Shallow v. Follwell: a Case Study

In the noted medical malpractice case, Shallow v. Follwell,  the Missouri Court of Appeals for the Eastern District of Missouri reversed and remanded a jury’s verdict for the defendant, Dr. Follwell, holding that the trial court improperly allowed cumulative expert witness testimony which imperiled the jury’s ability to fairly consider the quality and quantity of expert witness opinions.

The Shallow v. Follwell court held that the trial court abused its discretion in failing to properly determine when cumulative evidence should stop. The jury, therefore, heard the same opinions multiple times, or as the court noted:

“The problem with the trial court’s handling of the scope of the defense expert’s testimony is that all of them were permitted to not only provide opinions addressing the portion of the defense theory which touch on their specifically-endorsed expertise, but they were then allowed to offer a chorus of the same ultimate opinions.”

A Loss of Momentum

Calling too many experts to testify can be simply a waste of time for all involved. Imagine you were a juror in a major class action case. Now imagine each expert essentially repeats the same opinion on the same aspect of a case, one after another. It slows down the momentum for a case and noted progress in convincing a jury is lost as a juror struggles just to focus on hearing repeated information.

When You Can’t Just Have One

While a trial team would certainly consider limiting the number of experts involved from a cost and time factor, deploying a strategy of multiple experts may, in fact, still be necessary. While experts in a particular field may have similar education and professional standards, no two experts are the same. Each chosen expert can be used to provide additional, unique testimony to a case. The lawyer in turn can provide a jury with more explanations that detail the different ways the incident affects the plaintiff.

The Puzzle Piece Strategy

Courts prefer that evidence be used in a manner that fits together logically like puzzle pieces. For example, with an industrial pollution case in which a plaintiff was poisoned due to an industrial level accident, a logical approach is necessary. A lawyer may require an expert to discuss the nature of the pollutant and its chemical properties. This would be followed by an expert on industrial transportation safety. Lastly, an expert on causation and medical injuries from exposure. Such an approach avoids a cumulative situation that could likely damage the credibility of the plaintiff’s case. It also shows that the lawyer has provided an expert for each aspect of the matter as it relates to the accident and injuries of a plaintiff. The overall evidence in turn is being clarified by the experts who know those subject matters.

Experts Working as a Team

Besides ensuring that experts do not testify in a manner that is cumulative, another approach involves sharing information from a lawyer to all experts simultaneously. In turn, this creates a system or platform by which all the experts on a case are participating together. Likewise, this leads to a teamwork approach. The lawyer can direct the nature of the case and verify evidence with all the experts. Each expert, in turn, can assist another expert or converse together about their future testimony. This removes any doubt as to how an expert’s testimony fits into the larger strategy.

An expert witness provider can help an attorney build a team of experts to opine on liability, causation, and damages that maximize a client’s chance of success. Ultimately, this is a time-saving approach that can move your case closer towards a victory for the plaintiff.

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