Three subsections, two kinds of expert
A non-retained expert is a witness who will give opinion testimony under Federal Rule of Evidence 702, 703, or 705 but who was not retained or specially employed to do so, and whose job does not regularly involve giving expert testimony. In a search case that witness is usually the in-house SEO manager who watched the rankings fall, the agency account manager who ran the campaign, or the developer who repaired the site afterward. Each formed opinions before anyone was sued. Rule 26(a)(2)(C) of the Federal Rules of Civil Procedure governs how those opinions are disclosed.
The rule works in three layers. Rule 26(a)(2)(A) requires a party to disclose the identity of any witness it may use at trial to present evidence under Rule 702, 703, or 705. Rule 26(a)(2)(B) adds a signed written report, but only “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.” Rule 26(a)(2)(C) covers everyone else: the disclosure “must state: (i) the subject matter on which the witness is expected to present evidence under Federal Rule of Evidence 702, 703, or 705; and (ii) a summary of the facts and opinions to which the witness is expected to testify.” Rule text: Cornell LII.
One caution first. No reported decision I have found applies Rule 26(a)(2)(C) to an SEO manager, agency employee, or web developer by name; every search application here is an analogy from treating-physician, fire-investigator, and construction-contractor cases.
Why the 2010 amendment created the summary disclosure
Subsection (C) took effect December 1, 2010. The Advisory Committee said it was added “to mandate summary disclosures of the opinions to be offered by expert witnesses who are not required to provide reports under Rule 26(a)(2)(B) and of the facts supporting those opinions.” The Note warns courts against requiring undue detail from witnesses who were never specially retained, while still requiring that the opinions and their supporting facts be summarized.
The Note's examples are “physicians or other health care professionals and employees of a party who do not regularly provide expert testimony,” and it adds the sentence that does most of the work in a search case: such a witness “may both testify as a fact witness and also provide expert testimony under Evidence Rule 702, 703, or 705.” That is the hybrid witness.
Where the line falls between a (C) witness and a retained expert
The courts ask where the opinion came from. In Downey v. Bob's Discount Furniture Holdings, Inc., 633 F.3d 1 (1st Cir. 2011), the witness was the exterminator who had treated the plaintiffs' bedbug-infested home and proposed to testify that the infestation came from a sofa the defendant sold. The First Circuit reversed his exclusion, distinguishing “a percipient witness who happens to be an expert” from one who “comes to the case as a stranger and draws the opinion from facts supplied by others, in preparation for trial.” The Ninth Circuit framed the same point as a limit in Goodman v. Staples The Office Superstore, LLC, 644 F.3d 817 (9th Cir. 2011): the exemption reaches only opinions “formed during the course of treatment.”
The closest analogy to a search witness is a construction case. In Indianapolis Airport Authority v. Travelers Property Casualty Co. of America, 849 F.3d 355 (7th Cir. 2017), the Authority designated under (C) two witnesses from its contractors. The Seventh Circuit held the Authority “was not required to produce full Rule 26(a)(2)(B) reports” and limited the two to personal knowledge gained on the project.
By analogy, the in-house SEO manager who wrote contemporaneous reports explaining why organic traffic (visits arriving from unpaid search results) fell is the Downey exterminator for the opinions in those reports. If counsel later hands her the defendant's backlink export (a list of the pages on other sites that link to a given site) and asks her to opine on it, Goodman points toward a (B) report for that opinion. The agency account manager is the Indianapolis Airport contractor employee, limited to what the agency did and observed. And an in-house SEO who has testified repeatedly for the same employer risks classification as one “whose duties as the party's employee regularly involve giving expert testimony,” a (B) witness by the rule's own text.
What the summary must say, and the document dump that is not one
The failure I see most often is the disclosure that names a subject and stops. “Jane Doe, Director of SEO, will testify regarding the decline in the plaintiff's organic search traffic and its causes” satisfies prong (i) and nothing else. In Solache v. City of Chicago (N.D. Ill. January 23, 2023), disclosures for two hybrid witnesses that “listed subjects without summarizing opinions or facts” were held insufficient, and the court ordered supplementation by a date certain.
The other failure is attaching the file and calling it a summary. In Ballinger v. Casey's General Store, Inc. (S.D. Ind. March 29, 2012), the court held that “medical records alone do not comply with Rule 26(a)(2)(C),” a summary being “a brief account that states the main points of a larger body of information.” The Eighth Circuit affirmed exclusion on the same reasoning in Vanderberg v. Petco Animal Supplies Stores, Inc., 906 F.3d 698 (8th Cir. 2018): “Nor can the hundreds of pages of medical records reasonably be called a ‘summary.’”
Four hundred pages of Google Analytics 4 exports (GA4 is Google's current web analytics platform, which records visits and on-site events) are the hundreds of pages of medical records. What the cases require is the opinions stated as opinions, for example that the decline began in the week of a stated date and coincided with the defendant's redirect (a server instruction sending visitors and search engines from one URL to another) of named domains, and the facts behind them: her Google Search Console exports (Search Console is Google's free reporting service showing a site owner how the site performs in Google Search) for stated date ranges and the agency's monthly reports. The spreadsheet is the exhibit, not the disclosure.
The designation costs the communications protection
Rule 26(b)(4)(C) protects communications between a party's attorney and “any witness required to provide a report under Rule 26(a)(2)(B),” subject to three exceptions. The 2010 Note is direct about the limit: “The rule does not itself protect communications between counsel and other expert witnesses, such as those for whom disclosure is required under Rule 26(a)(2)(C).” Draft protection is different. Rule 26(b)(4)(B) covers drafts of “expert reports or disclosures,” and the Note says it applies to (C) witnesses too. Counsel can draft the summary with the witness without exposing the drafts; the conversation itself is another matter.
United States v. Sierra Pacific Industries (E.D. Cal. May 26, 2011) shows what the other doctrines are worth once the designation is made. The court found two government fire investigators designated under (C) were hybrid fact-and-expert witnesses and held that “by designating White and Reynolds as non-reporting expert witnesses, the United States waived otherwise applicable privilege and work-product protections.” It compelled production of the communications and permitted re-depositions on them. That is one district court, and the question has been answered differently elsewhere.
The exposure differs by seat. The in-house SEO manager's communications with company counsel are candidates for the employer's attorney-client privilege, which Sierra Pacific treats the designation as waiving. The agency employee and the outside developer usually have no privilege to begin with: their emails with the client's counsel about what happened to the site are discoverable, and so are the agency's internal tickets, chat messages, and monthly reports.
Timing, deposition, supplementation, and the sanction
The (C) disclosure runs on the same clock as the full report. Rule 26(a)(2)(D) sets the default at “at least 90 days before the date set for trial or for the case to be ready for trial,” or, for rebuttal evidence on the same subject matter identified by another party “under Rule 26(a)(2)(B) or (C), within 30 days after the other party's disclosure.” Deposition sequencing differs: Rule 26(b)(4)(A) permits a party to depose “any person identified as an expert whose opinions may be presented at trial,” and its only-after-the-report condition attaches to witnesses who owe a report.
The sanction is the same for both. Under Rule 37(c)(1), a party that fails to disclose “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.” The Seventh Circuit called that exclusion “automatic and mandatory” in Musser v. Gentiva Health Services, 356 F.3d 751 (7th Cir. 2004), and Vanderberg called the rule “a self-executing sanction” that does not require bad faith. The outcome of a thin disclosure tracks timing and prejudice, not thinness alone.
Can the other side's SEO manager be made to give an opinion?
Often, within limits. A (C) witness has knowledge of the events in dispute, so testimony about what the agency did or what the developer found is compellable as fact testimony. The opinion is harder. In Kaufman v. Edelstein, 539 F.2d 811 (2d Cir. 1976), the government subpoenaed two computer-industry consultants to testify about advice they had given clients. The Second Circuit found “no sufficient basis in principle or precedent for holding that the common law recognizes any general privilege to withhold his expert knowledge.”
Rule 45, which governs subpoenas, codified the balance. Rule 45(d)(3)(B)(ii) lets a court quash or modify a subpoena that requires “disclosing an unretained expert's opinion or information that does not describe specific occurrences in dispute and results from the expert's study that was not requested by a party,” unless under Rule 45(d)(3)(C) the serving party shows substantial need and “ensures that the subpoenaed person will be reasonably compensated.” The 1991 Committee Note states the principle: “Experts are not exempt from the duty to give evidence, even if they cannot be compelled to prepare themselves to give effective testimony.” Rule text: Cornell LII.
What follows is analysis, not a holding. The opposing party's SEO manager, deposed as an adverse (C) witness, can be asked what she concluded at the time and why; that is a previously formed opinion about specific occurrences in dispute, which Rule 45(d)(3)(B)(ii) by its words does not reach. What she cannot be compelled to do, absent the Rule 45(d)(3)(C) showing, is run a new analysis of the other side's data.
Frequently Asked Questions
Does an in-house SEO manager have to write an expert report, or can the party just disclose her?
It depends on where her opinions came from. Rule 26(a)(2)(B) requires a signed report only from a witness retained or specially employed to give expert testimony, or an employee whose duties regularly involve giving it. An SEO manager whose opinions were formed in her own work before the lawsuit fits the non-retained category and is disclosed under Rule 26(a)(2)(C) with a statement of subject matter and a summary of facts and opinions. If counsel supplies her new material and asks for opinions on it, the treating-physician cases such as Goodman point toward a full report for those opinions. No reported decision applies the rule to an SEO witness by name; this is analogy.What must a Rule 26(a)(2)(C) disclosure contain?
Two things: the subject matter on which the witness is expected to present evidence under Federal Rule of Evidence 702, 703, or 705, and a summary of the facts and opinions to which the witness is expected to testify. The rule does not require the witness's signature, qualifications, a publication list, a testimony list, or compensation, though a court order or stipulation can add requirements. The 2010 Committee Note calls the disclosure considerably less extensive than a report, but district courts have held that naming a subject without summarizing opinions and facts is insufficient, and that attaching records in place of a summary does not comply.Are emails between counsel and a non-retained expert protected from discovery?
Not by Rule 26(b)(4)(C). That protection is limited by its text to communications with a witness required to provide a report under Rule 26(a)(2)(B), and the 2010 Committee Note states that the rule does not itself protect communications between counsel and witnesses disclosed under Rule 26(a)(2)(C). Other doctrines such as attorney-client privilege may apply, but in United States v. Sierra Pacific Industries the court held that designating two employees as non-reporting experts waived otherwise applicable privilege and work-product protections. Drafts of the disclosure itself are protected under Rule 26(b)(4)(B), which applies to all witnesses identified under Rule 26(a)(2)(A).When does a non-retained expert become a retained expert who needs a full report?
When the opinion was formed for the litigation from material supplied by others rather than in the course of the witness's own involvement in the events. The First Circuit in Downey distinguished a percipient witness who happens to be an expert from one who comes to the case as a stranger and draws the opinion from facts supplied by others in preparation for trial. The Ninth Circuit in Goodman held that the exemption extends only to opinions formed during the course of treatment. A witness can be both, non-retained for opinions formed in her own work and retained for opinions developed later from counsel's materials, and the second set requires a report.Can a non-retained expert be subpoenaed to give an opinion?
As to opinions already formed about the events in dispute, generally yes, subject to the court's discretion. Kaufman v. Edelstein found no general common-law privilege to withhold expert knowledge, and the 1991 Committee Note to Rule 45 states that experts are not exempt from the duty to give evidence even though they cannot be compelled to prepare themselves to testify effectively. Rule 45(d)(3)(B)(ii) permits a court to quash a subpoena seeking an unretained expert's opinion that does not describe specific occurrences in dispute and results from study no party requested, unless the serving party shows substantial need and ensures reasonable compensation under Rule 45(d)(3)(C).Is the deadline for a (C) disclosure the same as for a full report?
Yes. Rule 26(a)(2)(D) applies to both. Absent a stipulation or court order, the disclosure is due at least 90 days before the date set for trial or for the case to be ready for trial, and a disclosure intended solely to contradict or rebut evidence on the same subject matter identified by another party under Rule 26(a)(2)(B) or (C) is due within 30 days after the other party's disclosure. The 2010 Committee Note confirms that the rebuttal deadline applies to summary disclosures just as it does to reports. Most scheduling orders set their own dates, and those control. Missing the deadline triggers Rule 37(c)(1).What happens if the non-retained expert disclosure is too vague?
The outcome depends on timing and prejudice more than on the thinness itself. In Solache v. City of Chicago, disclosures that listed subjects without summarizing opinions or facts were held insufficient and the court ordered supplementation by a date certain. In Ballinger v. Casey's General Store, the court confined the witness to observations contained in the records, barred causation testimony, and refused a late supplement that would have left the opponent no time to find a rebuttal witness. In Vanderberg v. Petco, the Eighth Circuit affirmed exclusion of the causation opinions and summary judgment, noting that allowing the evidence would almost certainly have required a continuance. Rule 37(c)(1) does not require bad faith.Published