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The Top Five Mistakes Expert Witnesses Make

This paper was originally prepared at the request of a client, a professional accounting firm, for presentation to the partners in the firm as part of their in-house training. The partners of the firm frequently are retained to serve as expert witnesses in trials and arbitrations.

Every attorney who has had extensive experience in working with expert witnesses will have his or her own "list" of the more troublesome problems and pitfalls encountered along the way. This is mine.


An expert is a person with specialized knowledge, skill, experience, training, or education which qualifies that person to form helpful opinions for a party in anticipation for litigation or preparation for trial. The court must find, however, in addition to the expert's qualifications, that the opinion evidence will be relevant to the issues in the case, that it is reliable, and that it will be helpful to the trier of fact.

It is the specialized knowledge or skill, or other attribute listed above, which permits a person to form and offer opinion evidence, rather than fact evidence, and it is the ability to offer opinion testimony which distinguishes the expert witness from fact witnesses.

MISTAKE #1 - Relying only upon information provided by the attorney.

Although I never use the words "never" and "always," in my opinion the expert witness should always insist upon a written agreement which clearly defines the scope of the expert's engagement (and the manner in which his or her fee will be paid) and the expert witness should never blindly accept the lawyer's word for all things critical to the project.

The attorney is an advocate for his or her client's position and legal rights and remedies. The expert is not. The attorney may have a tendency to present or color possibly negative or harmful facts in a light which makes them seem better than they are. The attorney may attempt (overtly or possibly even subconsciously) to mold or restrict the retained expert's work in order to ensure a favorable opinion. Instead, that attorney is only ensuring disaster, for himself, his client, and for the expert.

It is the expert's first responsibility, therefore, to ensure that he or she has a full knowledge of all the underlying facts (at the very least those which impact the area of the opinion solicited) and full access to all relevant records. Merely accepting the word of the attorney, or the client, that, for example, "generally accepted accounting principals were consistently applied," or that "the Board of Directors was informed and approved the transaction," without verification, can have a devastating effect upon the expert's credibility if proved wrong. And, if the expert's credibility is successfully impeached on any point, it is impeached on every point.

So, always do your own due diligence and investigate all the underlying facts and assumptions you may be given. Never put total faith and reliance in what you are told.

MISTAKE #2 - Forgetting That You Are an Advocate Only for Your Own Opinions, and Your Methodology, but not for the Case Itself.

Expert witnesses are much like fact witnesses in one respect: each one should tell the truth, simply, directly, and with sincerity.

Everyone by now knows of the landmark cases in the United States Supreme Court and the Supreme Court of Texas, Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993) and E.I. du Pont De Nemours and Company, Inc. v. Robinson , 923 S.W.2d 549 (Tex. 1995), respectively. Those cases changed forever the standard of proof for admitting expert testimony and caused the legal world to focus more and more upon the expert witness's methodology rather than merely upon his or her credentials as an "expert." In 1998, the Supreme Court of Texas extended this standard to "non-scientific" areas as well, such as accounting and other professional disciplines. Gammill v. Jack Williams Chevrolet, Inc., 972 S.W.2d 713 (Tex. 1998) The court is now the "gatekeeper" of expert testimony, and a court will not permit an expert to testify unless satisfied that he or she not only has sufficient and valid credentials to pose as an expert in the field in which testimony is sought, but that the expert's methodology was also valid, meaning that he or she developed the opinions through a proper application of his or her specialized knowledge to a given set of facts or assumptions in a manner which is scientifically reliable and has been exposed to peer review. The jury , however, as the trier of fact, is the sole judge of the credibility of all witnesses, including experts.

An expert witness must be objective. The jury will quickly detect any specialized agenda the expert may have, and the expert's credibility is directly proportional to the extent of the jury's belief, i.e. its perception, in his or her objectivity. An objective expert views all facts and underlying data unemotionally and without regard to how the client or attorney wants them viewed. The attorney is an advocate; it is his job to take a side and argue it with passion and conviction (within the parameters of factual reality and legal precedent). It is not the expert's job to be an advocate for the client, only for the objective truth. Trying to fit an opinion into a preconceived objective or goal will be the death knell of the expert's credibility, and, therefore, the case.

MISTAKE #3 - Putting Too Much in Writing, Too Soon, and Too Casually.

We are living in the age of discovery, the process of forcing the other side (including experts) to divulge every fact and thought about a lawsuit long before the dispute ever sees the inside of a courtroom. In discovery, there is one fundamental rule: if it’s in writing, it can be had.
Expert witnesses are, not surprisingly, real people…just like lawyers and clients. Without an extreme amount of discipline and self-denial, we all have a tendency today to send a quick e mail, or maybe a "memo," instead of picking up the telephone and calling, to discuss a point or make a statement or reveal a doubt or weakness about a position. And things written leave records for all the world to see.

Generally speaking, in the world of expert witnesses there are several types of writings. For example, there are "reports," there are drafts of reports, there is correspondence, there is electronic mail, there are memos, and there are personal notes (which may be in a notebook, on a napkin, on a desk calendar or "Day Timer," or even on the old fashioned sheet of paper). And, what is the rule? Right. "If it's in writing, it can be had."

My practice, and strong preference, is that if a report is not required, do not do one. If you do not do one, it cannot be discovered. Only the court, by direct order or by inserting the requirement in a case scheduling order, can make the expert prepare a written report.

But, a "report" may not be just the formal document, prepared (hopefully) and signed by the expert and intended to be the expert's final work product, including an expression of opinions to be submitted in the case. A "report" may be any written communication between the expert and the attorney in which the expert expresses his or her opinions, even in preliminary form. And, it can be (and nowadays very often is ) contained in electronic mail. Furthermore, for some strange reason, we seem to have a tendency to put things in electronic mail that we would never dream of putting in "real" writing. Everything from bad jokes to scandalous commentary…everything. We simply act like it isn't real, as if it vanishes like the disappearing ink we used as children did. Well, as any divorce lawyer will tell you, it doesn't!

Finally, if you do have to prepare a report, by all means prepare it yourself ! Do not let an attorney write "your" report for you. In that regard, do not let him revise your report, either. If you must, draft the report as you think it should read and then discuss it with the attorney. If anything needs to be clearer, or maybe placed elsewhere for greater emphasis or persuasiveness, then talk about it, do not write about it.

And, beware of metadata! If you don't know what metadata is, now is the time to find out, not later.

MISTAKE #4 - Being Myopic.

"Myopia," according to Webster's Collegiate Dictionary, 11th Ed. , is a lack of foresight or discernment, a narrow view of things. And, one who suffers from myopia is, of course, myopic.
So, how does this affect expert witnesses and their testimony? Well, the answer is, in several ways.
The most prevalent way is that a myopic person tends to get blindsided quite a bit. If you are myopic and have blinders on, or have "target fixation," as the Army used to say, and cannot see a broad enough picture to anticipate surprises from unseen positions, your effectiveness as an expert will be compromised and you will have a very long and uncomfortable time in the witness chair. In fairness, this is as much the attorney's fault as the expert's, maybe more so, but it will be you who are attacked on the witness stand. All the attorney can do is sit and squirm.

MISTAKE #5 - Sounding too much like an "expert."

Clear communication is the key to many relationships. Whether it is a spousal relationship, heads of state, or witness and jury, effective communication is vitally important. I have learned two rules over the course of my career, and I find I do better when I remember to follow them than when I don't.

The first is, Be Sincere . When I was a young lawyer, just learning the inside of a courtroom, I asked an older, wiser attorney for some advice and guidance, like what was the most important trait a good trial lawyer should have. His answer has stayed with me for over thirty years. "Michael," he said, "the single most important thing a trial lawyer can ever have is credibility…and, credibility is brief." In other words, he was telling me that long, flowery, excessive and exaggerated arguments and questions—or answers—are not nearly as good as a few well chosen words. And, you won't be surprised to learn, the ability to use the right few well chosen words to tell your story is most often the product of organization and preparation.

The second "rule" is, Never Talk Down to the Jury . Even if the jury is not "there," such as a deposition, never, ever talk down to them. Remember this, each person on the jury is an expert, just as you are. Will Rogers once said, "Everyone is ignorant, only on different subjects." That could be said another way, as well,…"Everyone is an expert , only on different subjects." So, they may not be experts in the same field as you, or as each other, and they certainly may not have the same level of education or letters after their names, like C.P.A., J.D., or PhD. for example, but they ARE experts in what they do. And, for however long the trial may last, as a matter of law they are experts on the facts of the case being tried and on the credibility of each witness, including you.

In essence, just be yourself.

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