A party seeking to offer opinion testimony is required to provide a written disclosure of that proposed testimony to the opposing side or risk exclusion of that testimony. However, the type of disclosure required depends on the background of the witness and the subject matter of the proposed testimony. Specifically, Federal Rule of Civil Procedure 26(a)(2)(B) requires a full written disclosure for retained experts who are employed to provide expert testimony, while Rule 26(a)(2)(C) requires a summary of opinions and facts, typically for non-retained experts. But which disclosure standard applies is not absolute, and disputes may arise along the way regarding which disclosure requirements apply and whether the disclosures provided are sufficient. Understanding the distinction between Rule 26(a)(2)(B) and Rule 26(a)(2)(C) can help litigants not only reduce the risk that their own expert testimony is limited or excluded but also identify potential deficiencies in an opposing party’s expert disclosures.
This article examines how courts distinguish between Rule 26(a)(2)(B) and Rule 26(a)(2)(C) witnesses, discusses common disclosure deficiencies, and highlights practical considerations for avoiding expert disclosure disputes.
The Two Paths Under Rule 26(a)(2)
Rule 26(a)(2) requires disclosure of any witness who may present expert testimony under Federal Rule of Evidence 702, 703, or 705.
Below we discuss the two primary forms of disclosure:
1. Rule 26(a)(2)(B): Full Expert Reports
Rule 26(a)(2)(B) applies to:
- Retained experts
- Witnesses specially employed to provide expert testimony
- Employees whose duties regularly involve giving expert testimony
These witnesses must provide a comprehensive written report, including:
- A complete statement of all opinions and the basis and reasons for those opinions;
- The facts or data considered;
- Supporting exhibits;
- The witness’s qualifications;
- A list of the prior testimony during the previous 4 years; and
- A statement of compensation for the study and testimony in the case.
Fed. R. Civ. P. 26(a)(2)(B).
The purpose of this requirement is to provide sufficient notice so opposing parties can prepare to address the expert’s opinions at deposition and trial. In practice, this disclosure form is commonly used in matters involving technical or specialized knowledge, such as intellectual property disputes involving technical infringement analysis or damages computations.
2. Rule 26(a)(2)(C): Summary Disclosures
Rule 26(a)(2)(C) applies to witnesses who are not required to provide a full expert report. These are often non-retained experts, such as employees who have unique firsthand knowledge of events relevant to the matter or dispute.
Rather than provide a full, detailed report, a Rule 26(a)(2)(C) witness must disclose:
- The subject matter of their testimony; and
- “a summary of the facts and opinions to which the witness is expected to testify.”
Fed. R. Civ. P. 26(a)(2)(C).
Although this requirement is less burdensome than the full-report requirements of Rule 26(a)(2)(B), parties must still disclose the witness’s actual opinions and a summary of the facts that support those opinions. The disclosures must state actual opinions (not just topics), which go beyond generalized or conclusory assertions. For example, merely referencing large volumes of documents, without summarizing the core opinions and factual support from those documents, is likely to be insufficient.
How Courts Distinguish Between Rule 26(a)(2)(B) and Rule 26(a)(2)(C) Witnesses
Courts have taken different approaches to determining whether a witness falls under Rule 26(a)(2)(B) or Rule 26(a)(2)(C). In Cedant v. United States, 75 F.4th 1314, 1317 (11th Cir. 2023), the Eleventh Circuit held that “what matters is when and why an expert witness came to the case, not the content of his testimony,” adopting a relationship-based approach that focuses on the witness’s connection to the litigation. Similarly, in Downey v. Bob’s Discount Furniture Holdings, Inc., 633 F.3d 1, 8 (1st Cir. 2011), the First Circuit emphasized that a full report is generally required when “the expert comes to the case as a stranger and draws the opinion from facts supplied by others, in preparation for trial.”
Other courts have focused more heavily on the circumstances under which opinions were developed. Under the Ninth Circuit’s approach in Goodman v. Staples The Office Superstore, LLC, 644 F.3d 817 (9th Cir. 2011), opinions developed outside a witness’s ordinary involvement and for purposes of litigation may trigger Rule 26(a)(2)(B)’s reporting requirements. Courts have generally held that “[i]t is irrelevant for purposes of Rule 26 whether an expert has been compensated for his or her testimony or simply volunteers that testimony.” Spears v. United States, No. 05:13–CV–47–DAE, 2014 WL 258766, at *8 (W.D. Tex. Jan. 23, 2014).
Accordingly, the inquiry generally focuses on the witness’s relationship to the litigation, the reason the witness became involved in the case, and whether the opinions were developed through the witness’s ordinary involvement or instead for purposes of litigation. Litigants should therefore be aware that the proper classification of a witness may vary depending on the governing jurisdiction and the particular circumstances under which the opinions were formed.
Consequences of Noncompliance
Failure to comply with Rule 26 disclosure requirements carries significant risk. Under Fed. R. Civ. P. 37(c)(1), a party may be prohibited from using the witness or information at trial unless the failure is “substantially justified or harmless.”
Although courts articulate the analysis differently, they generally consider similar factors when determining whether exclusion is appropriate. For example, the Fourth Circuit considers: “(1) the surprise to the party against whom the evidence would be offered; (2) the ability of that party to cure the surprise; (3) the extent to which allowing the evidence would disrupt the trial; (4) the importance of the evidence; and (5) the non-disclosing party’s explanation for its failure to disclose the evidence.” JFJ Toys, Inc. v. Sears Holdings Corp., 237 F. Supp. 3d 311, 326 (D. Md. 2017) (quoting Southern States Rack & Fixture, Inc. v. Sherwin–Williams Co., 318 F.3d 592, 597 (4th Cir. 2003)).
In practice, disclosure disputes can result in a range of consequences, including limitations on the scope of expert testimony, exclusion of certain opinions, or exclusion of the expert altogether. Because the applicable standards and remedies may vary by jurisdiction, litigants should consult the controlling authority in the relevant forum when evaluating the consequences of a disclosure deficiency.
Level of Detail: Where Parties Often Fall Short
A recurring issue in expert disclosures is whether the disclosure provides sufficient detail regarding the witness’s opinions and their bases for those opinions. Such disputes can arise under both Rule 26(a)(2)(B) and Rule 26(a)(2)(C). In the Rule 26(a)(2)(C) context, courts routinely reject disclosures that merely identify broad subject areas or topics for testimony without describing the opinions themselves. For example, in Timpson ex rel. Timpson v. Anderson County Disabilities & Special Needs Board, 31 F.4th 238, 253–54 (4th Cir. 2022), the Fourth Circuit affirmed exclusion of expert testimony where the disclosures identified only the subject matter of the expected testimony and did not provide the required summary of facts and opinions. The court also noted that the plaintiffs pointed to no record evidence demonstrating compliance with Rule 26(a)(2)(C).
In contrast, courts have found Rule 26(a)(2)(C) “easily satisfie[d]” where the disclosure identifies the opinions to be offered and provides a summary of the supporting facts. For example, in Hotels of Deerfield, LLC v. Studio 78, LLC, 621 F. Supp. 3d 1285, 1297–98 (S.D. Fla. 2022), the court concluded that the disclosure satisfied Rule 26(a)(2)(C) where it described the specific opinions the witness would offer, including why the defendants’ plans were incomplete, noncompliant with the Florida Building Code, and unsuitable for their intended use. The disclosure was also accompanied by an affidavit explaining the factual bases for those opinions and a memorandum further detailing the witness’s analysis, factual findings, and conclusions. Taken together, those materials provided both the subject matter of the testimony and a substantive summary of the facts and opinions to which the witness was expected to testify.
The takeaway is that Rule 26(a)(2)(C) requires enough information to provide notice of the witness’s opinions and their basis, but courts often apply that requirement with greater flexibility than the full-report requirements of Rule 26(a)(2)(B).
Expert Testimony Limits Apply to Both Categories
Regardless of the disclosure pathway, all expert testimony is subject to Federal Rule of Evidence 702 and the court’s gatekeeping role under Daubert.
This includes several important limitations:
- Testimony must be based on sufficient facts or data;
- It must reflect reliable principles and methods;
- It must assist the trier of fact; and
- It cannot offer legal conclusions.
Experts may address underlying facts, industry practices, and technical analysis, but they cannot resolve ultimate legal issues reserved for the court.
Strategic Considerations for Litigants
Although a witness’s classification under Rule 26(a)(2)(B) or Rule 26(a)(2)(C) depends on the witness’s role and anticipated testimony, litigants should consider several practical issues when evaluating potential expert witnesses and preparing disclosures. Key considerations include:
- The Witness’s Role and Opinions: Is the testimony based on the witness’s firsthand involvement and preexisting knowledge, or were the opinions developed for purposes of litigation? The answer may affect whether a full report is required.
- Jurisdictional Approach: Courts do not all apply the same framework when distinguishing between Rule 26(a)(2)(B) and Rule 26(a)(2)(C). Litigants should consider how the governing jurisdiction approaches the issue.
- Cost Considerations: In some circumstances, a non-retained witness may provide the necessary testimony without the expense associated with retaining an expert and preparing a full report.
- Credibility and Bias: Different categories of witnesses may present different credibility considerations. Retained experts may face scrutiny regarding compensation, while employee or other non-retained witnesses may face scrutiny regarding their relationship to a party.
Ultimately, the appropriate path depends on which type of witness provides the most credible and legally persuasive testimony for the issue at hand.
Key Takeaways
Rule 26 provides two distinct expert disclosure frameworks with different requirements. The line between Rule 26(a)(2)(B) and Rule 26(a)(2)(C) is not always clear, and courts have adopted different approaches for determining which category applies. While Rule 26(a)(2)(C) disclosures are less demanding than full expert reports, they must still provide fair notice of the witness’s opinions and supporting facts. Regardless of the disclosure category, expert testimony remains subject to Rule 702, Daubert, and the prohibition on legal conclusions.
But regardless of which disclosure is required for a witness, from a practical standpoint, litigants should leave no doubt and ensure that the disclosures provide fair notice of all opinions and adequately identify the supporting facts the witness intends to offer.
Authors: Christopher Smith & Madeline Withers
About Brooks Kushman P.C.
Founded in 1983, Brooks Kushman P.C. has built a national reputation as a premier intellectual property and technology law firm. We accomplish this with the understanding that the most effective IP solutions come from putting great minds together – our clients and our own. With offices across the country, we forge strong relationships with corporations, small to medium-sized businesses, and leading universities across the country.
Brooks Kushman counts a number of Fortune 100 Corporations across a variety of industries among its clients. Our attorneys have a deep understanding and broad range of experience in a variety of industries and technologies, including automotive, AI & data, automation, consumer electronics, manufacturing, medical device, computer technology, aerospace, chemicals, biotechnology, retail, food & beverage, green technology, fintech, and more. We are also recognized by leading legal publications and rankings, including, Best Lawyers, Law360, Intellectual Asset Management, Managing Intellectual Property, and World Trademark Review. For more information, please visit www.BrooksKushman.com.
