December 14, 2016 Practice Points

Cross-Examination of the Expert Witness in Deposition

“No substitute has ever been found for cross-examination as a means of separating truth from falsehood, and of reducing exaggerated statements to their true dimensions.”

By Phillip A. Cole

In professional-liability litigation, the expert testimonies supporting and refuting the claim are critical components of the evidence. In fact, it is required in all but the most obvious of errors, that a plaintiff support his or her allegations with expert testimony. The defendant is in a unique position because he or she is also an expert witness with regard to the liability and, usually, the causation issues. The defendant accordingly will have two experts assessing the issues in the case. Defendant’s counsel must engage an independent expert but must not overlook the expert testimony to be given by the client.

The premise in this short essay is that the case at hand is justiciable and will be presented to a jury. Expert depositions can also be useful in settlement negotiations, but lawyers typically know the weakness in the expert testimony before depositions are taken. The expert’s deposition is planned and executed with the trial in mind. The deposition is in practice nothing less than the first phase of the expert’s examination in court. A party’s own expert is prepared with the same objective in place.

Beginning with Francis Wellman’s 1919 classic, The Art of Cross Examination, volumes have been written on cross-examining witnesses, especially experts. Wellman’s advice, reiterated by most writers—to ask only leading questions and be brief—does not apply in a discovery deposition of an expert. The object in the deposition is to pin the expert to a position and to require the expert to stake the credibility of opinions on assumptions the expert is making. It should not be necessary to spend much time on the expert’s credentials. The examiner has no interest is laying foundation for the expert’s credibility, but may wish to attack it where there is a potential Daubert issue.

The essential vulnerability of the expert witness is that he or she is not a fact witness. The expert is confined to the facts and must not be allowed to stray from them. In cases headed for a jury trial, there will always be material issues of fact in dispute. The expert witness is on one side of that dispute in his or her factual assumptions. The deposition must require the expert to stake his or her opinions on his or her factual assumptions. What is achieved in this regard is direction on the emphasis to be given in the presentation of the fact evidence.

Perhaps the most significant evidentiary advantage given to a lawyer deposing an expert is the use and admissibility of learned treatises in the examination of the expert. Preparation for an expert deposition requires exhaustive research of the learned treatises pertinent to the issues in dispute. These treatises abound in medicine and the law and can be quite useful in intellectual-property issues. Every learned treatise supporting a lawyer’s position in a case represents essentially another expert witness and at very low cost. In the case of learned treatises in legal-malpractice litigation, lawyer experts are, in my experience, resistant to accepting a publication with adverse comment as a learned treatise. The foundation problem can be overcome by assuring that one’s own expert and the lawyer client will testify to establish foundation. Foundation is usually not an issue in medicine where the literature seems to be more respected.

In using the learned treatise in a deposition, it is usually not the best practice to expose the actual treatise to the witness. It is, after all, not the aim of the examination to educate the witness. The better practice is to expose the contrary position taken in the literature as a proposition of the examiner’s and require the witness to respond in agreement or disagreement. In trial, however, the treatise should be fully exposed to the jury along with the contrary position of the expert.

When Francis Wellman authored The Art of Cross Examination, depositions were not a commonplace feature in litigation. He wrote with a sole focus on the jury trial. The deposition in modern litigation has the same focus, and Wellman’s statement in Chapter II of his work still holds true: “No substitute has ever been found for cross-examination as a means of separating truth from falsehood, and of reducing exaggerated statements to their true dimensions.”


Phillip A. Cole is with Lommen Abdo, P.A., in Minneapolis, Minnesota.


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