Federal Rule 26(a)(2) Expert Witness Disclosures: Strategies for Composing and Attacking Expert Disclosures


Given the highly technical issues that can arise in litigation, experts often play a critical role. A plaintiff who fails to come forward with sound expert testimony in support of her theory of liability risks summary dismissal. Conversely, any defendant who lacks expert testimony to support his defenses realistically faces a poor outcome.

There are many steps that counsel should take to ensure that she has expert testimony at her disposal. Among these is compliance with the requirements of FederalRule of Civil Procedure 26(a)(2). Even the most articulate expert armed with the most sound opinions will do a party little good if the expert is excluded due to a failure to properly disclose during discovery.

The purpose of Rule 26(a)(2) is to provide notice to opposing counsel—before the deposition—as to what the expert witness will testify and this purpose would be completely undermined if parties were allowed to cure deficient reports with later deposition testimony. Allowing parties to cure a deficient report with later depositions would further undermine a primary goal of Rule 26(a)(2): to shorten or decrease the need for expert depositions. After all, the parties’ need for expert depositions would increase if they could use deposition testimony to provide information they should have initially included in their Rule 26(a)(2) report.

The Rule

Federal Rule of Civil Procedure 26(a)(2) requires a party to disclose the identity of any witness who will provide expert testimony under Federal Rule of Evidence 702, 703, or 705.1 Absent a court order or stipulation, a party must make the required disclosure—either a full report under Rule 26(a)(2)(B) or the more limited disclosure under Rule 26(a)(2)(C)—at least ninety days before trial.

Expert opinions intended only as rebuttal testimony must be exchanged within thirty days of the initial disclosure. A party also has a duty to supplement any incorrect or incomplete information provided in her expert disclosures by the time the party’s pretrial disclosures are due. However, this rule does not provide an opportunity to disclose new opinions after the original deadline for expert disclosures has passed.


UnderRule26(a)(2)(B), a party that intends to rely upon the testimony of a retained expert witness is required to furnish a report containing, among other information, a complete statement of all opinions the retained expert will provide, and the basis and reasons for them.

The report must contain: (1) a complete statement of all opinions to be expressed and the basis and reasons therefore; (2) the facts or data considered by the witness in forming her opinion; (3) any exhibits that will be used to summarize or support her opinion; (4) the witness’s qualifications, including a list of her publications for the previous ten years;(5) a list of all other cases in which she has testified in the previous four years; and (6) a statement of the compensation to be paid for her testimony.

The report may not merely set forth an ultimate opinion without providing a line of reasoning arising from a logical foundation. The report must not be sketchy, vague, or preliminary in nature, and it must include ‘how’ and ‘why’ the expert reached a particular result, not merely the expert’s conclusory opinions.

There is a well-accepted notion that expert witnesses cannot testify about facts or data, but fail to disclose the same. Where an expert has not identified specific facts or data considered. . . [her] report is useless in preparing for cross-examination.


Failure to timely disclose the above-described information asrequired by Rule 26(a) means that the party has yet to properly disclose these witnesses as experts. Under Rule 37(c)(1), exclusion of  non-disclosed  evidence is  automatic  and mandatory ...unless non-disclosure was justified or harmless. Thus, the sanction for failure to disclose includes a shifting of the burden to prove that the violation was “justified or harmless” to the non-producing party.

Courts consider the following four factors when determining whether an inadequate disclosure is harmless: (1)the prejudice or surprise to the party against whom the evidence is offered; (2) the ability of the party to cure the prejudice; (3) the likelihood of disruption to the trial; and (4) the bad faith or willfulness involved in not disclosing the evidence at an earlier date.

Without proper disclosures, a party may miss its opportunity to disqualify the expert, retain rebuttal experts, or hold depositions for an expert not required to provide a report. As a result of these and other ways a party may be prejudiced by an improper disclosure, the sanction is severe, and there is no exception for substantial compliance. Accordingly, a failure to comply with Rule 26(a)(2)’s disclosure requirements results in the offending party not being permitted to introduce the expert witness’s testimony as ‘evidence on a motion, at a hearing, or at a trial.’


As evidenced above, failure to timely comply with the dictates of Rule26 could result in your expert witness being stricken entirely or being barred from providing certain opinion testimony. Given the dire consequences that may result from a failure to adhere to the rule, careful attention should be paid to proper compliance.

Prepare Early

As with many errors that occur in the practice of law, waiting until the last minute to focus on an expert’s report substantially increases the likelihood that the report will be flawed. Preparation for timely and compliant disclosures necessarily begins with an early determination of what experts are necessary for your particular case. Engaging the right expert at the early stages of a case is critical in determining whether the technical theories you wish to advance are supportable. A good expert is indispensable in fleshing out the challenges that may exist in proving your theories and identifying the flaws in your opponents theories. The earlier a party can bring the right experts on board the better.

Retaining the expert is certainly just one step in avoiding last-minute disclosures. Keeping the expert updated and aware of deadlines is also critical. A sure fire way to ruin an expert’s day is to call or email her with an announcement that you need her report by the end of the week. Another way to cause panic is to inform the expert only days before the report is due that some vital piece of information was forgotten. One way to avoid last minute issues is to set a deadline for the expert to share a draft report well in advance of the disclosure deadline. Rule 26(b)(4) protects such “drafts.” Rule 26(b) also states that the work-product privilege of Rule 26(b)(3)(A) protects communications between the party’s attorney and a testifying expert unless the communications relate to compensation for the expert’s study or testimony, identify facts or data that the party’s attorney provided and that the expert considered in forming the opinions to be expressed; or (iii) identify assumptions that the party’s attorney provided and that the expert relied on in forming the opinions  to be expressed.”

However, note that the exact contours of confidentiality in this area are not clearly defined. For example, different courts have interpreted the meaning of a privileged “draft” report differently.

Review the Report Through an Adversary’s Eyes

In order to lessen the chances of the report being excluded, it is important to review the report thoroughly for compliance. When conducting such a review, consider the level of attention that your opponent will devote to finding flaws. At a minimum, counsel should subject the report to the same level of scrutiny.

Conducting the review as the opponent would necessarily mean that you do not just take the expert’s word that she has made a proper disclosure of the required information. Perhaps the most obvious place to begin when conducting the review is with a determination of whether the expert has included all of the opinions and supporting facts that are necessary to support the theory for which the party is using her. A good method to do so is to go through a mock direct and cross examination of the expert’s expected trial testimony. If the expert needs to draw upon opinions and facts that are not in the report in order to testify adequately, the report is undoubtedly flawed.

The expert must also disclose all facts or data “considered by” the witness in forming her opinion. As part of this requirement, most experts will list the materials they have reviewed. It is good practice to check that list to determine whether the expert has omitted any vital information. It may be that the expert has deliberately chosen not to utilize a particular source. However, even if that is correct, it is worthwhile to at least understand why the expert chose not to consider the source.

In addition to disclosing all facts or data “considered by” the witness in forming her opinion, Rule 26(a)(2)(B)(i) requires disclosure of the “basis and reasons” for the expert’s opinions. All too often, experts skip directly from observations to conclusions without describing or, indeed, performing a process by which the observations have been evaluated, analyzed, or calculated to produce their conclusions. This is particularly problematic where quantitative conclusions are stated based on qualitative observations without intervening quantitative analysis. Some courts are less strict in enforcing this aspect of the rule than others, but the careful practitioner will want to both see and disclose the analytical process employed by her expert. Mathematics has been said to be the language of science, and advocates purporting to advance scientific theories should employ that language.

Moreover, although the expert may believe that she has listed her publications and cases for the relevant time periods, doing separate research into these topics prior to the report’s due date can reveal new cases or publications that may not only be absent from the list, but also may not have been available when counsel first vetted the expert. Performing a LexisNexis search for cases and publications will help ensure that the expert has not omitted required information.

No Ghostwriting

On occasion, it may be tempting to write the expert’s report and merely have the expert summarily bless and sign it. Resist  this temptation. Where an expert report is required, the report must be prepared and signed by the witness. Courts interpret the requirement that the report be “prepared” by the expert as requiring the expert, not the attorney who retained the expert, to draft the report. In fact, “numerous courts  have  admonished attorneys for ghost-writing their experts’ reports, going as far as to preclude experts from testifying.

This does not mean that a lawyer is precluded from providing assistance to experts in preparing the reports. The advisory committee notes to Rule26 expressly contemplate attorney involvement in drafting the expert’s report. Thus, an attorney’s involvement in drafting the expert report does not some-how make the report inadmissible. However, the report must be written in a manner that reflects the testimony to be given by the witness.


An opponent’s failure to comply with the dictates of Rule26 can prejudice your ability to retain rebuttal experts, or hold depositions for an expert not required to provide a report. Accordingly, proper steps should be taken to limit the prejudice, including moving to strike the opponent’s expert testimony.

Determine Whether the Report is Technically Compliant

As previously stated, the required contents of the report are extensive, and the report provided by the expert must be detailed and complete. These requirements are not mere formalities. Expert reports have been excluded for a variety of reasons including occasions where (1) the expert’s opinions were largely unsupported; (2) the expert’s qualifications were omitted; (3) there was no statement of the compensation received; and (4) the expert’s previous testimony was not included. As a result, carefully determine whether the opponent’s expert report satisfies each of these conditions.

To do this, make a checklist of each of the items that must be included in the report and carefully comb through the expert report to make sure each of the items is present. This will require independent research. For instance, LexisNexis searches can be performed that list the cases in which the expert has provided testimony, and searches may be performed on other platforms, such as JSTOR, to find publications authored by the expert. Some of this analysis may even necessitate the use of the party’s own expert, who will be able to point out instances in which the opponent’s expert failed to provide support for an opinion. As counsel performs this analysis, she should note any discrepancies between the actual disclosure and what should have been disclosed.

This method was used to exclude an expert in a recent aviation case. In granting the motion, the court held that it was “particularly disturbing” that the expert did not include a “complete and useful list of trial or deposition testimony for the last four years.” The court stated that “Rule 26 requires more than attempted compliance; it requires mandatory disclosure of all deposition and trial testimony within the past four years, together with sufficient information about where that testimony was given to enable the opposing party to gain access to it.” This basis alone was sufficient to exclude the witness, thereby demonstrating the importance of notating when an expert disclosure is not complete.

Exposing Weaknesses in the Expert’s Report

Problems with an expert’s report are not always readily apparent from the face of the report and sometimes can only be determined by deposing the expert. When addressing the report during the expert’s deposition, first have the expert admit that (1) she was required to disclose any and all opinions in her report; and (2) she has no other opinions other than those contained in the report. Make clear to the expert that thedeposition is not a means for her to supplement her report with additional opinions. This helps to prevent the opponent from later claiming that any failure to disclose washarmless.

Pursuant to Rule 37(c)(1), “exclusion of non-disclosed evidence is automatic and mandatory...unless non-disclosure was justified or harmless.” In determining whether the failure to disclose was harmless, courts consider, in part, the prejudice or surprise to the party and the ability to cure the prejudice. To the extent that the expert attempts to testify regarding an opinion not contained in her report, make the objection to the new opinion clear and indicate the prejudices caused. By failing to object, counsel runs the risk of the opponent later claiming that any prejudice from the failure to disclose was cured at the deposition.

With respect to the facts and data that were to be disclosed within the report, again have the expert concede that she was required to list all facts and data that she considered. Counsel should then devote a portion of the deposition to determining whether the expert relied on any facts or data missing from the report. Indeed, in preparing for the deposition, make your own assessment of whether there are documents that the expert likely needed to render her opinions but were not disclosed. If the expert agrees that she should have considered the missing information, there is a basis to claim that the report lacks a logical foundation. If, on the other hand, the expert claims that she did review the missing information but did not list it, there is a basis to claim improper disclosure.

Ways to Limit Prejudice

Ifanexpert’sdisclosureisinsufficient,itbecomesimperative that the harmed party begins limiting the degree of prejudice borne from the inadequate disclosure. Although the best out-come will be the exclusion of the expert, there are many in-stances in which the court will not elect to disqualify the improperly disclosed expert. As a result, consider alternatives to limit the prejudice that has occurred.

When making a motion to exclude, point out to the court every aspect of the expert disclosure that makes it inadequate and each of the prejudices that the inadequacies will cause.When done properly, courts are often amenable to, at a minimum, limiting the testimony that the expert is permitted to provide. In addition to this sanction, counsel may also file a motion for the payment of the reasonable expenses, including attorney’s fees, caused by the failure. When facing a court that does not wish to strike the expert, counsel may also seek more creative sanctions. For example, counsel may ask to re-depose the expert after having an appropriate amount of time to prepare.


Obtaining credible expert testimony is critical to a successful outcome in most aviation cases. Rule 26(a)(2) provides the requirements for expert witness disclosures. If an expert fails to meet these requirements, the opposing party may move to exclude the expert’s testimony. There are many steps that prudent aviation counsel should take to ensure that her expert is not excluded, including properly determining the status of the witness as a retained or non-retained expert, timely preparing the expert and the required disclosure, and critically reviewing the prepared disclosure for any compliance issues.

Conversely, the opposing counsel, upon receiving an inadequate disclosure, must limit the prejudice caused by it. After determining that the report is not technically compliant, opposing counsel should take additional steps to expose those weaknesses, including through the use of well-crafted deposition questions. While the ultimate goal is to have the expert’s testimony excluded, counsel should also keep in mind that there are other methods to limit the prejudice caused by the noncompliant disclosures. Adherence to these strategies will limit the prejudicial effect of the improperly disclosed expert testimony.

Adapted from Source: Douglas B. Bates, et al., Federal Rule26(a)(2) Expert Witness Disclosures: Strategies for Composing and Attacking Expert Disclosures, 83J. Air L. & Com. 67 (2018)

Rhonda Harper - Expert Witness

Rhonda Harper is routinely retained to formulate expert surveys, conduct rebuttal critiques, or construct rebuttal surveys to show the potential difference in results with properly designed and executed surveys. She has extensive experience and a deep understanding of survey design, sampling, question construction, data analysis, and methodological pitfalls that introduce bias or systematic error.

Located in Dallas, TX, Rhonda Harper has been retained by 95+ law firms since 2005. With a focus on Trademark and Trade Dress Infringement, Misleading and Deceptive Advertising, Licensing, and Commercial Reasonableness cases, Rhonda Harper has conducted hundreds of research studies, including 50+ Likelihood of Confusion and Secondary Meaning surveys. She has been deposed ~50 times and served in ~20+ trials and arbitrations.

Contact: Rhonda Harper at 214-244-4608 or rhonda@rhondaharperllc.com.