Preparing Your Expert Witness for Trial – A Checklist

One of the worst things an expert witness can do on the stand is to seem unprepared.

Testifying in Trial as an Expert

ByMehjabeen Rahman, J.D.


Published on September 26, 2016


Updated onAugust 26, 2021

Testifying in Trial as an Expert

Once the jury feels that a witness is unprepared, it is very difficult to repair confidence in that expert. However, thorough preparation before your expert’s turn on the stand can avoid the damage that an unprepared witness can inflict on your case. To make this easier, we’ve compiled a concise checklist also available as a free download for reference when preparing your expert witness for trial. So that your expert can provide the most effective testimony possible.

Prepare the Court for Your Expert

Although your expert’s testimony may be at the crux of evidence presented at trial, there are several preliminary steps that must be taken before your expert can testify. Important rules prescribed by both statutes and the courts govern pretrial proceedings. Failure to adhere to these rules could result in disastrous consequences for your expert’s testimony. Refer to the corresponding rules of procedure and evidence to avoid any issues in the pre-trial phase.

Pre-Trial Housekeeping

  • The Federal Rules of Civil Procedure 16(b) governs pre-trial scheduling and gives deference to any local court or judge rules. So be sure to check all the necessary deadlines in your jurisdiction.
  • With respect to the time for disclosing expert testimony, rule 26(a)(2)(D) prescribes that such disclosures should be made according to the time and schedule the court orders. However absent a court order or stipulation between the parties, disclosures concerning expert testimony should be made at least 90 days before the trial date.
  • If the expert is required to provide a written report under rule 26(a)(2), then such a report has already been disclosed prior to the expert’s deposition under rule 26(b)(4)(A).
  • Note that certain objections can be raised by opposing counsel under 26(a)(3)(B) anytime until 30 days before trial is set it take place. These objections will be discussed in further detail below, but check the rules as just a reminder about grounds on which objections to your expert’s testimony can be made.
  • For these types of pre-trial housekeeping matters, Google Docs, DropBox or other file-sharing web services are great for communicating quickly and efficiently with your paralegal, who may be scheduling any pre-trial meetings. For a closer look at a list of similar apps and services that can really help you and your staff prepare an expert for trial, see this article.
  • Also, consult Rule 26 for the contents of the disclosure including the expert’s name, qualifications, a summary of testimony and other details the rules or the court require.
  • Always remember to supplement any disclosures about your expert or your expert’s testimony about any material changes, as provided under FRCP rule 26(e). Failure to properly supplement any pre-trial disclosures can result in sanctions under FRCP Rule 37(c).

Admissibility Issues

The general rule is that if objections are not raised during a deposition, the objection is waived forever. However, there are a number of objections that opposing counsel can still raise concerning the admissibility of your expert witness’ testimony before the trial takes place. The key is to wholly understand the language of the rule itself; especially in conjunction with any exceptions that are made explicit. Be sure to keep these rules in mind when combing through your expert’s testimony so you can be prepared when such objections are raised before the court at any pre-trial hearings.

  • FRCP rule32(b) makes it clear that, subject to certain exceptions, an objection may be made at any hearing or even at trial as to the admissibility of any deposition testimony that would be inadmissible if the witness were present and testifying.
  • FRCP rule 32(d) provides a list of objections that are waived if not raised at the time of the offensive conduct or defect. However pay close attention to rule 32(d)(3), which notes that objections to the relevance, materiality, or competence of a witness or a witness’ deposition testimony can be made at any time and are not waived for failure to raise them.

These governing rules of procedure correspond directly to a number of Federal Rules of Evidence:

  • Rule402 governs the general admissibility of relevant evidence
  • Rule403 governs the admissibility of evidence that may be unduly prejudicial, confusing, a waste of time or otherwise inappropriate to present at trial.

Many last minute problems with admissibility can be avoided if one gives a careful reading of the rules in addition to understanding the scope and limits of discovery prescribed by FRCP Rule 26, particularly 26(b)(4) which deals specifically with trial preparation for experts.

Qualifying Your Expert

In a worst case scenario, opposing counsel can make a motion to disqualify your expert witness. Especially if an expert witness seems unprepared, opposing counsel may use this as grounds to contest the reliability of the expert’s testimony. If the court agrees, then your witness is no longer qualified as an expert and the jury will be instructed to wholly disregard the expert’s testimony. Of course, preparation is key to avoid this kind of problem; but familiarity with the Federal Rules of Evidence is also a must when concerned about expert witness qualification.

  • FRE Rule702 prescribes when an expert witness’s testimony is necessary
  • FRE Rule703 broadly describes the bases on an expert’s opinion and it is here that the Daubert factors are relevant for federal court (Frye standard for DC courts).
  • Be sure to review these rules with your expert and explain that at the crux of his testimony is the data and methodology on which he relied to form his opinions. This is what will be the most vulnerable aspect of his substantive testimony. As opposing counsel will try hard to question the reliability of the expert’s methods.
  • While preparing for trial, communicate with your expert and ask if there are multiple ways of doing a particular study, or controversy surrounding test methods, etc. This way you will have explored the potential pitfalls in your expert’s methodology, and can be ready to help your expert when the basis of his or her expert opinion comes under attack.

Prepare Your Expert for Court

It can be easy to overlook the fact that experts are not attorneys, and may not be naturally comfortable in a courtroom environment. The best way to help your expert and ultimately, your client, is to discuss all the relevant legal aspects of their testimony, as well as any nuances they should be aware of when presenting their testimony to the jury.

Substantive Law Issues

  • Make sure to discuss attorney-client privilege with the expert witness. Under the FRCP, attorney-client privilege does not extend to witnesses, however, certain protections are afforded to trial preparation materials of expert witness testimony under the work-product privilege doctrine.
    • Specifically, FRCP Rule 26(b)(4)(B) provides protection for any drafts of expert reports or disclosures, regardless of the form in which the draft was recorded.
    • FRCP Rule 26(b)(4)(C) offers protection for communications between the attorney and expert witnesses, but note that this protection only applies for experts who have to provide a written report under 26(a)(2). This protection is also subject to several exceptions, so be sure to review these and discuss them with your expert.
  • Under FRE Rule608-613, there are different grounds on which your expert witness can be impeached that have little to do with the substance of your expert’s actual testimony, such as character for truthfulness, a prior criminal conviction, and prior inconsistent statements. Explain what this means to your expert so he isn’t caught off guard when the questioning during cross deviates from the subject of the witness’ expertise and wanders into the realm of character and credibility.
  • Sometimes witnesses may make statements that are outside the scope of their expertise, like a conclusory statement about a legal claim, which a jury will be instructed to disregard if a proper objection is raised. Briefly explain to your client the difference between the legal merits of the case and the factual issues that he is there to help the jury decide.

Direct Examination

Direct examination is your chance to paint the picture of your case to the jury, and when concerning an expert, the best chance to present your witness’ testimony. Having a plan of attack is key, especially with respect to the more highly technical aspects of your expert’s testimony.

  • Instruct your witness to avoid using “absolutes”. This means making statements like “in all cases” or “every time”. This way, the witness does not close to the door to a certain line of questioning and open himself up to impeachment later. It should be expected that opposing counsel will try to “pigeonhole” the witness’ testimony this way, so be sure to go over this with your expert.
  • Instruct the expert not to frame answers in a way to appears partial to one side or the other. This is significant, since bias is a valid grounds for disqualifying an expert witness. Remind your expert of the role that he plays during direct examination and the litigation generally.
  • Ask open-ended questions that will allow the expert to elaborate on the most important points of testimony.
  • Take the lead on how to engage the jury. Discuss tips with your expert on how to rephrase some technical explanations and make them easier to understand. For example, expert witnesses in the medical field have a tendency of using technical terms such as “radial,” “distal” and “proximal,” which few jurors understand. Brainstorm with your expert better ways to present this information that will keep the jury interested in your expert’s testimony. The most knowledgeable expert in the world will do little to help your case if the jury is asleep.
  • Ask anticipated cross-examination questions. This strategy of “beating them to the punch” so to speak will not only catch opposing counsel by surprise and weaken their strategy on cross; but will also demonstrate to the jury that you and your expert have explored any potential problems in the testimony and have addressed them to the court vis-à-vis a proper counter argument or explanation.


No matter how many times an expert has testified at trial, being grilled during cross-examination is always incredibly stressful. This is one of the only chances opposing counsel will have to directly poke holes in your case by attacking the credibility of your expert’s testimony. The best way to prepare your expert for facing difficult questions on cross is to practice them with your experts.

“Yes” or “No” Questions

  • For all yes or no questions, framing is key for both the expert and the cross-examiner. The attorney’s objective on cross is to weaken the expert’s testimony and thus will undoubtedly frame “yes” or “no” questions in such a way to achieve that purpose.
  • If a question is difficult to answer by simply stating “yes” or “no,” let your witness know it is perfectly fine to tell the questioning attorney that such a simple answer cannot be provided in that context. This way, it makes clear that your witness is not evading a difficult question, but is rather answering in the most accurate way possible.
  • Another strategy to handle this type of question is to say “in some circumstances” if that is the case. This way, you are not misleading the court by answering yes or no if the answer truly is “sometimes”. This paints a better picture for your expert as a credible witness and also weakens opposing counsel’s line of questioning.

“I Don’t Know” Answers

  • Sometimes, based on a desire to please the attorney and the court, experts may get ushered into answering a line of questioning outside the scope of their expertise. Remind your witness that “I don’t know” is a perfectly acceptable answer, as long as that is the truth. This is extremely important, since your witness can only make statements that fall within the scope of your witness’ expertise and any statements made otherwise will be stricken from the record.
  • Be sure to discuss with your expert instances where “I don’t know” is NOT an acceptable answer, such as when the question directly relates to a basis or methodology of your expert’s opinion.

Getting Cut Off

  • In many instances, opposing counsel may cut off your expert in the middle of an answer, especially if the answer isn’t favorable to their story of the case. Discuss different strategies of how to approach this problem with your expert witness, so important parts of testimony are not left out.
  • For example, instruct your witness that if there is some important portion of testimony that needs to be included, then the witness should take the liberty of saying what needs to be said.
  • If the attorney insists on cutting off your witness, instruct your witness to answer the next question by stating the previous question was not completely or accurately answered.
  • Remind your witness to leave the door open for clarification on re-direct. This means that when opposing counsel asks your witness “is that everything,” it is crucial that your witness provides a flexible answer, such as “that is all I can recall at the moment”. Failure to do so may be grounds for impeaching your witness, or at the very least looks somewhat conflicting to the jury.

Keeping Emotions in Check

  • Expert witnesses may respond poorly to perceived hostility on cross-examination. Remind your expert not to get defensive if they feel attacked by a line of questioning. If it’s objectionable, you as the attorney will take care of it.
  • Remind your witness that the objective of a cross-examination is not to pick a fight with the attorney, but an opportunity for the witness to “stick to their guns” and present an even stronger case to the jury for your client. Maintaining a resolve and not being overcome by emotions or getting flustered under pressure is the most important part of an expert’s mindset when on the stand.
  • The most important tip to remind your witness is to stop, breathe and think about the question being asked before providing an answer. This way, your witness does not call out uncertain answers based on a pressure to perform. The priority is and always should be not to compromise the credibility or image of your witness to the jury.

Lights, Camera, Courtroom

There are a number of considerations outside of the substance of witness testimony – such as appearance, demeanor, and word choice – that can and will have an influence on the jury. Preparing an expert for trial is stressful. So it is easy to forget the little things that can make a big difference in the overall trial presentation.


  • Do not over-prepare the witness as it makes the testimony seem fake, fabricated or too “rehearsed”. This meansavoiding buzz-words and key-phrases.
  • Remind your expert to maintain eye-contact with the jury. This is one of the most important aspects of testimony presentation and keeping the jury engaged.
  • Remind your expert to keep hand motions to a minimum unless necessary for demonstration.
  • Maintain an even and consistent projecting volume when speaking to the jury.
  • Your expert must answer clearly. This means avoiding “uhm” and “nu-uh” and the like.
  • Curtail other distracting habits such as:
    • Nail-biting
    • Fidgeting with pens or pencils
    • Rocking back and forth in the witness seat
    • Playing with a watch or jewelry


  • Make sure your expert dresses professionally and appropriately for court.
  • Tell your expert to avoid wearing any flashy jewelry or extravagant ties and scarves, as these can be distracting. The worst scenario is one where a juror remembers more about the expert’s clothing than their testimony.
  • If possible, do dress rehearsals with your witness.


There has been an explosion of the use of technology in courtrooms in the past few years. If you are planning to use “hi-tech” devices like iPads, projection screens, 3D imagery and the like as part of your expert’s testimony, be sure to:

  • Practice, practice, practice. You must practice running through the use of all these devices when preparing your witness for trial. A “technological glitch” makes your team look unprepared. As technology can be unpredictable it is crucial to go through the motions of using whatever devices you intend to use.
  • Remember all necessary wires, chargers, adapters, converters, flash drives and whatever other accessories or gadgets you may need.
  • Explore the particular courtroom set for trial and make sure that the facilities can accommodate the technology you plan on using.

The most difficult part of dealing with an expert witness is that trials are unpredictable. However, preparing your expert witness will help reduce uncertainty. Furthermore, careful and meticulous preparation of your expert witness will help you catch many potential issues early on and ensure an overall smoother trial process. Keep this list handy for a quick reference on tips to help you prepare your witness for trial and be sure to check our consolidated version of the checklist available here.

About the author

Mehjabeen Rahman, J.D.

Mehjabeen Rahman, J.D.

Mehjabeen Rahman, J.D., is a versatile legal professional, currently a Law Graduate at Gutman, Mintz, Baker & Sonnenfeldt. She has been serving as a Staff Writer and Legal Blog Author for the Expert Institute since September 2015, where she conducts expert interviews and writes advisory articles for the legal community.

Her hands-on legal experience includes internships at the Kings County District Attorney's Office in the Special Victims Bureau and the Community Legal Assistance- Law Reform Advocacy Clinic. At the DA's office, Mehjabeen assisted in case preparation and trial observation, and at the Advocacy Clinic, she managed litigation for a Civil Action case and argued pretrial motions. Additionally, she gained experience in criminal defense and motion drafting during her internship at Renfro, Driscoll & Foster, LLP.

Mehjabeen earned her Juris Doctor from Maurice A. Deane School of Law at Hofstra University, where she was a Mock Trial Team member, Clinic Student, and Associate Editor for the Hofstra Labor and Employment Law Journal. Her legal education and practical experiences underscore her expertise in legal research, writing, and trial preparation.

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