In federal civil litigation, Rule 26(a)(2)(B) generally requires retained or specially employed testifying experts to provide a written report, unless otherwise stipulated or ordered by the court. The report must disclose the expert's opinions, the basis and reasons for them, the facts or data considered, and other information required by the Rule.
This guide explains which expert witnesses must provide written reports, what Rule 26 requires those reports to contain, how Rule 702 relates to expert testimony, and what attorneys should review before disclosure.
Which Expert Witnesses Must Provide a Written Report?
Not every testifying expert in federal civil litigation must prepare a full Rule 26 report.
Rule 26(a)(2)(B) generally requires a written report when the witness is retained or specially employed to provide expert testimony or when the witness is a party's employee whose duties regularly involve giving expert testimony. The report must be prepared and signed by the witness.
Rule 26(a)(2)(C) addresses expert witnesses who are not required to provide a written report under Rule 26(a)(2)(B). Unless otherwise stipulated or ordered by the court, the disclosure must identify the subject matter on which the witness is expected to present evidence under Federal Rules of Evidence 702, 703, or 705. It must also summarize the facts and opinions to which the witness is expected to testify.
State courts may use different expert disclosure requirements, so counsel should confirm the applicable rules, local rules, and scheduling orders.
What Must a Rule 26 Expert Witness Report Include?
For an expert subject to Rule 26(a)(2)(B), the report must contain:
- A complete statement of every opinion the expert will express and the basis and reasons for each opinion
- The facts or data the expert considered in forming the opinions
- Any exhibits that will be used to summarize or support the opinions
- The expert's qualifications, including a list of all publications authored during the previous 10 years
- A list of all other cases in which, during the previous four years, the witness testified as an expert at trial or by deposition
- The compensation to be paid for the expert's study and testimony
When helpful, the report can organize the analysis into sections addressing the assignment, methodology, assumptions, calculations, limitations, or materials reviewed. However the report is organized, it must still cover all six required items above.
What Should Attorneys Review Before Disclosure?
Before serving an expert report, counsel should review it for completeness and consistency, including whether the expert's expected opinions and the basis and reasons for them are fully disclosed.
Counsel should also check the report against the expert's curriculum vitae, publications, prior testimony, compensation information, exhibits, calculations, and the facts or data the expert considered in forming the opinions. Missing or inconsistent information can draw scrutiny during expert discovery, including at the expert's deposition.
Rule 26 does not prohibit counsel from assisting with report preparation, and the 1993 Advisory Committee Note to Rule 26(a)(2)(B) recognizes that such assistance may be appropriate. Even with counsel's assistance, the report should reflect the testimony the witness expects to give and must be prepared and signed by the witness.
Clear explanations of necessary technical terminology can make the expert's reasoning easier to evaluate, although clear writing alone does not make an opinion more reliable.
Rule 702 and the Admissibility of Expert Testimony
Rule 26 governs expert disclosure in federal civil litigation. Federal Rule of Evidence 702 sets the core admissibility requirements for proposed expert testimony.
Under the current Rule 702, the witness must be qualified as an expert by knowledge, skill, experience, training, or education. The proponent must also demonstrate to the court that it is more likely than not that:
- The expert's scientific, technical, or other specialized knowledge will help the trier of fact understand the evidence or determine a fact in issue
- The testimony is based on sufficient facts or data
- The testimony is the product of reliable principles and methods
- The expert's opinion reflects a reliable application of those principles and methods to the facts of the case
A Rule 26-compliant report does not automatically make the proposed testimony admissible, and strong credentials alone do not resolve problems with an unreliable methodology or its application. Rule 26 addresses what must be disclosed, while Rule 702 addresses whether proposed expert testimony satisfies those admissibility requirements.
Frequently Asked Questions
Are Expert Witness Reports Required in Every Lawsuit?
No. Requirements depend on the jurisdiction, proceeding, type of expert, and applicable court orders. In federal civil litigation, Rule 26(a)(2)(B) generally requires full written reports from retained or specially employed testifying experts and certain party employees whose duties regularly involve giving expert testimony.
Can an Attorney Help Prepare an Expert Witness Report?
Rule 26(a)(2)(B) does not preclude counsel from assisting with report preparation, but the report should reflect the testimony the expert expects to give and must be prepared and signed by the witness.
Can an Expert Add Opinions After the Report Is Disclosed?
Sometimes, but Rule 26(e) does not automatically authorize a new opinion after the disclosure deadline. Under Rule 26(e)(1)(A), a party must timely supplement or correct an expert disclosure when it learns that the disclosure is materially incomplete or incorrect. This duty applies only if the additional or corrective information has not otherwise been made known to the other parties during discovery or in writing. For an expert required to provide a Rule 26(a)(2)(B) report, the supplementation duty also extends to information in the report and deposition, with additions or changes due by the Rule 26(a)(3) pretrial-disclosure deadline. A court may also order supplementation. Whether a genuinely new opinion may be added depends on Rule 26(e), the scheduling order, and controlling precedent.
Can Artificial Intelligence Be Used When Preparing an Expert Report?
The current Federal Rules of Civil Procedure and Evidence do not expressly address AI-assisted expert-report preparation. Counsel should check applicable local rules, standing orders, and case-specific orders. The Advisory Committee on Evidence Rules has stated that Rule 702 applies when a testifying expert uses AI to reach the expert's conclusion.
