Amendments To Expert Witness Discovery Under Federal Rule 26

Rule 26 of the Federal Rules of Civil Procedure was recently amended on December 1, 2010 to limit discovery that may be obtained from a party's testifying expert. Prior to these amendments, broad judicial interpretations led to parties seeking discovery of virtually all communications between counsel and expert witnesses, as well as drafts of the expert's report. As a result, parties were often forced either to enter into stipulations under which both sides would forego such discovery, or take costly and time-consuming measures to avoid such disclosure. The new amendments seek to address these issues and are of particular importance in the electronic discovery arena as experts on issues such as preservation, the adequacy of search terms, and whether ESI is not reasonably accessible because of undue burden or cost are becoming more prevalent.


The Federal Rules first addressed discovery as to trial expert witnesses in 1970, when Rule 26(b)(4) was added. That rule provided for "[d]iscovery of facts known and opinions held by expertsacquired or developed in anticipation of litigation or for trial," but only permitted interrogatories, with further discovery available only by court order.

Expert witness discovery was significantly broadened in 1993, when Rule 26 was amended to require a party to disclose "the identity of any witness it may use at trial to present [expert testimony]" as well as provide an expert report for any expert (i) "retained or specifically employed to provide expert testimony in the case" or (ii) "whose duties as the party's employee regularly involve giving expert testimony." These experts may also be deposed after the report is provided.

Under the 1993 amendments, the expert report had to include "the data or other information considered by the witness in forming [the opinions the witness will express.]" The Committee Notes accompanying the 1993 rule stated as follows:

The report is to disclose the data and other information considered by the expert and any exhibits or charts that summarize or support the expert's opinions. Given the obligation of disclosure, litigants should no longer be able to argue that materials furnished to their experts to be used in forming their opinions - whether or not ultimately relied upon by the expert - are privileged or otherwise protected from disclosure when such persons are testifying or being deposed.

As a result of judicial interpretation of this language, courts permitted litigants to take wide-ranging discovery of expert draft reports and communications between counsel and expert witnesses because such materials were held to be "information considered by the expert." To avoid disclosing this information, parties often retained two sets of experts, a "testifying" and a "consulting" expert, refused to discuss potentially risky issues with the testifying expert, avoided creating any draft reports, and/or avoided written communications with testifying experts. Such practices not only increased a party's litigation costs, but hindered the free flow of information between counsel and the testifying expert.

The Amendments Provide Increased Protections

The current amendments attempt to ensure that the expert's opinions and factual bases remain subject to scrutiny, while at the same time protecting counsel's mental theories or impressions. They do this in two ways. First, Rule 26(a)(2)(B)(ii) was amended to limit the disclosure obligation only to the "facts or data" considered by the expert. According to the Committee Notes, this change was specifically meant to restrict discovery of counsel's mental impressions or litigation theories shared with the testifying expert. The amended rule now limits disclosures only to "material of a factual nature."

Second, Rules 26(b)(4)(B) and (C) were added to provide work product protection for drafts of expert reports and communications between counsel and the expert, subject to the limited exceptions described below. According to the Committee Notes, Rule 26(b)(4)(C) was added to "protect counsel's work product and ensure that lawyers may interact with retained experts without fear of wholesale discovery." At the same time, discovery into the expert's opinions, including their development, factual foundation or basis, remains permissible. For example, the Committee Notes point out that proper areas of inquiry include, among other things, the expert's testing methods, the expert's communications with individuals other than counsel, and any alternate analyses, methods or approaches that the expert did not use.

Potential Limitations

While the new protections outlined in these amendments are broad, they are not without limits. First, communications between counsel and the expert may be discovered to the extent that they (i) relate to the expert's compensation, (ii) identify facts or data that the party's attorney provided and the expert considered in forming his or her opinions, or (iii) identify assumptions that the party's attorney provided and the expert relied upon in forming his or her opinions.

The Committee Notes provide important insights into the intended scope of these exceptions (particularly exceptions (ii) and (iii)). Specifically, exception (ii) is "limited to those facts or data that bear on the opinions the expert will be expressing, not all facts or data that may have been discussed by the expert and counsel." Moreover, it applies "only to communications 'identifying' the facts or data provided by counsel." Additional communications regarding the identified facts or data remain protected. For example, discussions concerning the relevance or effect of certain facts should remain protected. Exception (iii) is even narrower, applying only to communications identifying assumptions that the expert actually relied upon. It does not apply to "general discussions about hypotheticals, or exploring possibilities based on hypothetical facts." For example, while the expert must disclose the assumptions that he or she made, discussions with counsel regarding the effect or relevance of those assumptions are protected as privileged work product.

Second, protected materials may still be discovered if "the party has a substantial need for the discovery and cannot obtain the substantial equivalent without undue hardship." According to the Committee Notes, such a showing will be "the rare case." Moreover, even if such a showing is made, the court "must protect against disclosure of the attorney's mental impressions, conclusions, opinions, or legal theories."


The implementing order from the United States Supreme Court, as submitted to Congress, states that the amended rule shall govern in all proceedings pending on December 1, 2010, "insofar as just and practicable." Neither the amended rule nor the Committee Notes, however, address retroactivity. Moreover, at least one federal court has already concluded, in a different context, that the amendments to Rule 26 do not apply retroactively. William J. Lattuga v. United States Postal Service , Case No. 1:09-cv-416, Dkt. # 29. Therefore, until courts provide further guidance, parties to cases filed prior to December 1, 2010 should continue to be cautious when communicating with their testifying experts.

Published .