Mastering Expert Witness Discovery: The Ultimate Guide to Rule 26

    Rule 26 of the Federal Rules of Civil Procedure governs the disclosure of expert witness testimony during the discovery stage of litigation. In 2010, significant amendments were made to the rule to address some practical problems surrounding discovery as a result of earlier changes to the rule adopted in 1993. This allowed for broad discovery of attorney-expert materials. Based on interpretation by courts that the 1993 language made almost any material related to the expert’s opinion discoverable, attorneys often went to exhaustive lengths to protect attorney-expert work product, making the discovery process overly tedious. Moreover, to remedy this, greater protection was afforded to drafts of the expert’s opinion and communications between the attorney and the expert by amendments to FRCP Rule 26 in 2010.

    However, federal courts have come to slightly differing opinions as to the extent of these protections with respect to expert materials. Being familiar with the evolution of the rule’s effect on disclosures regarding expert witness testimony and the nuances in recent case law is the best way to protect against the exclusion of an expert opinion, which could be devastating to your case. Refer to this thorough guide to smoothly handle discovery issues when working with an expert witness. For your convenience we’ve prepared a downloadable checklist available right here:

    1) Know the Requirements

    FRCP Rule 26(a)(2)- Disclosure of Expert Testimony

    26(a) ( 2 ) (A)

    A party is required to disclose the identity of any expert witness. Under the rules, this is defined broadly as any witness that party plans to present evidence under Federal Rules of Evidence 702, 703 and 705 which govern admissibility of expert witness testimony.

    26(a) ( 2 ) (B)

    An expert must prepare, sign and submit a 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. This report must contain:

    1. a “complete statement” of the witness’ opinions,
    2. the “facts or data considered by the witness in forming them,”
    3. proposed exhibits summarizing or supporting the expert’s opinions
    4. the witness’s qualifications, including a list of all publications authored in the previous 10 years;
    5. 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
    6. a statement of the compensation to be paid for the study and testimony in the case.

    There are two important aspects of the changes made to Rule 26(a)( 2 ). One aspect served to make the rule more specific about the kinds of expert-related information generally discoverable from experts. Thus, the 1993 version of the rule that used to read: (ii) “the data or other information considered by the witness in forming [the expert opinions] was changed in 2010 to read: (ii) “the facts or data considered by the witness in forming the [expert opinions]”. The Committee Note also explained this change, stating that “[t]he Committee has been told repeatedly that routine discovery into attorney-expert communications and draft reports has had undesirable effects.”

    Specifically, the 1993 language in the rule including “other information” forced attorneys to go to great lengths to guard their draft reports and communications with experts. In many instances attorneys dealt with a dual set of experts. One for consulting and one for testifying to avoid disclosing the “core” or “opinion” work product substance of meetings with consulting experts. Therefore, litigants who could not afford dual experts were unfairly disadvantaged. In other circumstances, attorneys abstained from taking notes at all, compromising the quality of the attorney’s work and communications with experts. Consequently, experts felt pressured working under these restricted conditions and often impeded the expert’s process in forming a well-developed, thorough and sophisticated opinion.

    FRCP Rule 37(c)(1)- Failure to Disclose Expert

    If a party fails to provide information or identify a witness as required by Rule 26(a) or (e), the party is not allowed to use that information or witness to supply evidence on a motion, at a hearing, or at a trial, unless the failure was substantially justified or is harmless.

    FRCP 37(c)(1)(C)

    The rule further provides that “the court, on motion and after giving an opportunity to be heard …may impose other appropriate sanctions.”

    Ford Motor Co. v. Thermoanalytics, Inc., 2016 WL 1465015 (E.D. Mich. Apr. 14, 2016)

    Under FRCP 37, the court granted Plaintiff Ford’s motion to preclude portions of Defense expert witness’ testimony insofar as it relied on facts or data about Defendant Thermoanalytic’s finances that Defendants originally refused to provide, thus finding the refusal in violation of FRCP 26(a).

    2) Know What Kind of Expert Witness You Are Working With

    The second aspect to the 2010 changes made to Rule 26(a)( 2 ) was to make more clear which expert are required to provide a written report and which experts are not required to provide such a report.

    FRCP 26(a)(2)(C) Non-retained or employee witnesses

    For these kinds of witnesses who are not required to submit a written report, their disclosure must state:

    1. the subject matter on which the witness is expected to present evidence under Federal Rule of Evidence 702, 703, or 705; and
    2. a summary of the facts and opinions to which the witness is expected to testify.

    In some instances, expert witnesses offer both fact and opinion testimony. Common examples of these non-retained experts include the treating physicians in the case, other similar health care professionals, a party’s accountants or bookkeepers, an owner of a business giving an opinion on valuation of the business or a human resources employee who offers an opinion about the methodology chosen to justify employee lay-offs. Under the rules, these kinds of expert witnesses are not required to provide a written expert report, although some courts have still required one. The addition of rule 26(a)( 2 )(C) was therefore intended to settle this issue.

    1. Summary does not have to include facts or data relied upon in forming the opinion except for those on which the expert is expected to testify.
    2. The practical effect of the addition of subsection 26(a)(2)(C) is that lawyers may have to contact or meet with prospective testifying experts earlier in advance and also determine what opinions or facts the expert may have to offer on the stand.
    3. Protection for attorney work-product with respect to retained experts does not apply to non-retained or employee witnesses serving as experts. The Committee Note says “[t]he rule provides no protection for communications between counsel and other expert witnesses, such as those for whom disclosure is required under Rule 26(a)(2)(C).”
    4. An employee witness may also be a client of the employer’s lawyer, so conversations between the witness and the lawyer that are protected by the attorney-client privilege would not be discoverable.

    3. Know the Limits of What’s Discoverable

    FRCP 26(b)(4) Scope of Discovery and Limits for Expert Trial Preparation

    26(b)( 4 )(B)

    Governs trial preparation protection for draft reports or disclosures.

    Rules 26(b)( 3 )(A) and (B)5 protect drafts of any report or disclosure required under Rule 26(a)( 2 ), regardless of the form of the draft. The work product protection for draft reports applies “regardless of the form of the draft, whether oral, written, electronic, or otherwise.” Any drafts of supplements to a report are also protected.

    26(b)( 4 )(C)

    Governs trial preparation protection for communications between party’s attorney and expert witnesses

    Rules 26(b)( 3 )(A) and (B) protect communications between the party’s attorney and any witness required to provide a report under Rule 26(a)( 2 )(B), regardless of the form of the communications, except to the extent that the communications:

    1. relate to compensation for the expert’s study or testimony;
    2. identify facts or data that the party’s attorney provided and that the expert considered in forming the opinions to be expressed, (relating back to 26(a)(2)(B)) or
    3. identify assumptions that the party’s attorney provided and that the expert relied upon in forming the opinions to be expressed.

    Paragraphs (B) and (C) to Rule 26(b)( 4 ) also apply to “all forms of discovery” with respect to expert materials and not just depositions. However as the Committee Note points out, Rules 26(b)( 4 )(B) and (C) do not impede discovery about the opinions to be offered by the expert or the development, foundation, or basis of those opinions. Communications the expert had with anyone besides the attorney are also discoverable. In addition, attorneys are free to question expert witnesses about alternative testing methods, trials, or approaches to the issues on which they are testifying, whether or not they were considered by the expert in forming the opinions offered in the testimony.

    FRCP Rule 26(b)(5)- Claiming Privilege or Protecting Trial-Preparation Materials

    (A) Information Withheld. When a party withholds information otherwise discoverable by claiming that the information is privileged or subject to protection as trial-preparation material, the party must:

    1. expressly make the claim; and
    2. describe the nature of the documents, communications, or tangible things not produced or disclosed—and do so in a manner that, without revealing information itself privileged or protected, will enable other parties to assess the claim.

    4) Know Your Jurisdiction

    26(b)(4)(D) Experts employed only for trial preparation

    Ordinarily, a party may not, by interrogatories or deposition, discover facts known or opinions held by an expert who has been retained or specially employed by another party in anticipation of litigation or to prepare for trial and who is not expected to be called as a witness at trial. But a party may do so only:

    1. as provided in Rule 35(b) or
    2. on showing exceptional circumstances under which it is impracticable for the party to obtain facts or opinions on the same subject by other means.

    However, in states like North Carolina, parties are entitled to obtain expert disclosure only “through interrogatories.” The rule says a party ordinarily may not, as opposed to “must not.” Be sure to check the local jurisdiction’s rules with respect to interrogatories.

    Under New York Civil Practice Law and Rules (“CPLR”) Section 3101(d)( 1 )(iii), depositions and interrogatories of experts are not generally permitted. They are therefore only available on a showing of special circumstances.

    5) Always Be Prepared for in camera Reviews

    Pursuant to a discovery motion to compel information about an expert’s offered testimony, it is common practice for courts to hold in camera hearings, outside the presence of opposing counsel and also the jury, to determine whether the information sought warrants protection under the rules. Additionally, this is the opportunity to highlight why the communications sought would expose the kind of attorney work-product the rules are designed to protect.


    Since the 2010 amendments to Rule 26 of the FRCP governing discovery of expert witnesses, there has been little case law as to the issues and therefore an area slightly lacking in jurisprudence. Subtle differences in interpretation exist across district courts as well as major differences among jurisdictions on the state level. This thorough guide on the effects of these amendments is designed to help you tackle the discovery process when working with an expert witness.

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