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Tips for Preparing Your Expert Witness to Testify

Michael Robert Lied

Tips for Preparing Your Expert Witness to Testify
miniseries via Getty Images

First, a Question

Given the title of this article, this question may seem silly: Do you even need an expert? This author’s opinion is that—usually—the fewer the witnesses, the better, to minimize the chance of witness contradictions or other problems. Nevertheless, there are certain types of cases—for example, medical negligence—in which the law requires expert testimony. In many other cases, it may be a practical necessity to use one or more experts, but that is not always true. So you should consider whether an expert is needed or worth the cost under the circumstances. Answering the question will assist you in focusing the expert’s presentation to what is truly needed for your case.

Next, Check the Applicable Court Rules

In fact, double-check the applicable court rules. In federal court, look at Federal Rules of Civil Procedure 16 and 26(a), as well as Federal Rules of Evidence 402, 403, 702, 703, and 705, and how courts in your particular jurisdiction have interpreted and applied those rules. Your judge also may have his or her own practice rules specific to expert witnesses, and you also must consult any local rules. If you are in state court, it is obvious that you should review the applicable rules and case law. In answering affirmatively the question of whether you need an expert, you obviously have concluded that you need the expert witness to testify at trial. As a result, know the rules of admissibility and anticipate your adversary’s challenges well in advance to deal with them preemptively as much as you can in the expert’s report and in preparing the expert to testify at deposition and at trial.

The Expert’s Report

Under Federal Rule of Civil Procedure 26(a)(2), a party must disclose to the other parties the identity of any witness it may use at trial to present evidence under Federal Rules of Evidence 702, 703, or 705. 

Unless otherwise agreed or ordered by the court, this disclosure must be accompanied by a signed written report if the witness is one retained or specially employed to provide expert testimony in the case or one whose duties as the party’s employee regularly involve giving expert testimony. The report must contain the following:

(i) a complete statement of all opinions the witness will express and the basis and reasons for them;
(ii) the facts or data considered by the witness in forming them;
(iii) any exhibits that will be used to summarize or support them;
(iv) the witness’s qualifications, including a list of all publications authored in the previous 10 years;
(v) a list of all other cases in which, during the previous 4 years, the witness testified as an expert at trial or by deposition; and
(vi) a statement of the compensation to be paid for the study and testimony in the case.

Fed. R. Civ. P. 26(a)(2)(B).

Some expert witnesses are not required to provide a written report, but you must still disclose (1) the subject matter on which the witness is expected to present evidence under Federal Rules of Evidence 702, 703, and 705; and (2) a summary of the facts and opinions to which the witness is expected to testify.

How about timing? You must make these disclosures at the times and in the sequence that the court orders. Unless there is a stipulation or a court order, the disclosures must be made

(i) at least 90 days before the date set for trial or for the case to be ready for trial; or
(ii) if the evidence is intended solely to contradict or rebut evidence on the same subject matter identified by another party under Rule 26(a)(2)(B) or (C), within 30 days after the other party’s disclosure.

Fed. R. Civ. P. 26(a)(2)(D).

Be sure to supplement these disclosures when required under Federal Rule of Civil Procedure 26(e). Obviously, the report should cover the subject matter sufficiently for purposes of any motions to exclude, but it also should accomplish another goal: It should be well organized and clear not only so that it can educate the court if the report ever is challenged, but also so that you and your expert can use it as an easy reference tool during deposition preparation and during the deposition itself once it is made an exhibit. Even if the questioner does not make the report an exhibit early in the deposition, prepare your expert to feel comfortable asking to have the report made available so that he or she can refer to it in responding to questions.

The Expert’s Deposition

It goes without saying that you should locate and review any previous testimony by your expert. Preferably, you will have reviewed the expert’s prior testimony before even engaging the expert, but even if you have, go back over the testimony in light of how the facts of your case have developed and any strategies employed by your adversary. If you can get your hands on deposition transcripts, all the better, because the questioning will be more wide ranging than trial testimony. This allows you to get a sense of the possible attacks on the expert and how well the attacks were handled. Google, Westlaw/Lexis, social media, and PACER searches for publications, presentation, and court records related to the expert are worthwhile. Your opponent will likely do that.

For expert deposition preparation, assume your expert will be challenged under Daubert. In particular, carefully go over the sections of Federal Rule of Evidence 702 to be sure the expert’s proposed testimony will pass muster. In particular, the expert must be prepared to address (1) that his or her technique or theory can be (or has been) tested; (2) whether it has been subjected to peer review and publication; (3) whether there is a known or potential rate of error of the technique or theory and, when it has been applied, whether standards and controls exist and are maintained; and (4) whether the technique or theory has been generally accepted in the scientific community.

Prepare the expert for the deposition process itself like any other witness. This will include such factors as who is likely to be present in the deposition room, anticipated attitude and approach by the other lawyers, documents the witness is likely to be shown, whether the deposition will be videotaped, what it means to go off the record, and the fact that, despite there being objections, in most cases the expert will still have to answer. Prepare the expert for common questions such as his or her hourly rate, the amount paid, how often the expert testifies for a plaintiff or the defense, and the like. Also go over presentation (wear a suit); mannerisms (don’t fidget or put your hand in front of your face when answering); and, critically, that depositions are not conversations, so humor and colloquialisms should be avoided.

Make sure the expert understands where he or she fits into the entire case and theme of the case. The expert needs to understand that he or she may have a relatively limited role and should not be lured into opining on issues beyond those identified in the expert’s report.

Because the expert’s credibility is always an issue, the expert ideally should avoid looking partisan. If possible, the expert should not answer in a way that makes him or her appear partial to one side or the other.

Obviously, as for any other witness, “I don’t know” is a perfectly acceptable answer. Because few things in life are absolutely certain, the expert should avoid answering questions in absolute terms. “Always” can be a dangerous word.

While the questioner may demand a “yes” or a “no” for an answer, the witness should be reminded that he or she can state that a yes-or-no answer may not be sufficient under the circumstances. The questioner may try to cut off the expert’s answer. In preparing the expert, you should discuss how you will handle this, whether by having the expert insist on the right to finish the answer or through clean-up questions you will pose.

While most depositions are business-like, it is possible things may become heated. The expert must be cautioned to try to stay calm and focused. The expert must be prepared to stick to his or her position and conclusions, even in the face of questions that carry a tone of incredulity. Like fact witnesses, the expert may need to be reminded to leave some “wiggle room” in the answers, particularly if he or she fails to remember something while being questioned.

Expert Trial Testimony

Testimony in court will follow most of these same guidelines, but the expert should be reminded of a few additional points. First, the fact of being an expert doesn’t mean the expert must talk like an expert, especially in front of a jury. Work with the expert to try to reduce jargon or any appearance the expert gives that suggests he or she feels superior to members of the jury. The expert needs to be a teacher. Clear communication is the goal.

The midst of trial is not the time for waffling. The expert must be counseled to always answer an unobjectionable question.

Trials are a race to credibility and an exercise in maintaining credibility, so the expert’s credibility really comes to the fore in the trial. To the extent possible, the expert must be prepared to make eye contact with the finder of fact, whether it be the judge or the jury. Because the expert has already been deposed, it will likely be possible to anticipate cross-examination questions and prepare appropriate responses.

Inform the expert that even in a jury trial, the judge might ask one or more questions and that it is the expert’s job as a witness to wait for the court’s rulings on any objections before providing an answer. Remind the expert that the questioning at trial may be a bit like tennis, with direct, cross, redirect and re-cross. This may be multiplied if there are additional parties.


These suggestions may not be unique or novel, but they are tried and true and bear reviewing and repeating any time you are working with an expert. Covering these points will help your expert shine when it counts.