Does Disclosure of Privileged Information to a “Non-Reporting” or “Hybrid” Expert Waive Privilege?

Plaintiff KISS sought discovery of certain otherwise-privileged communications made by defendant Ardell to Ms. Theresa Cooper, an executive vice president at Ardell.  Initially, Ms. Cooper was designated as a fact witness. Later, she was designated as a “non-reporting expert” pursuant to Fed.R.Civ.P. 26(a)(2)(c).  The court explained that “Ardell’s Expert Disclosures state that it expects Ms. Cooper to testify about the same subject matter areas as were identified as the subjects of her testimony as a fact witness.”

Ardell asserted attorney-client privilege. KISS asserted waiver by disclosure to a designated expert.

SPLIT OF AUTHORITY OVER HYBRID EXPERTS

In KISS Nail Products, Inc. v. Ardell International, Inc., 2026 WL 180031 (C.D. Ca. Jan. 22, 2026), the court wrote:

The parties’ central dispute—whether the designation of a hybrid non-reporting expert witness waives privilege—is an issue that has divided district courts in recent years. Some courts, following the reasoning of United States v. Sierra Pac. Indus., No. 09-cv-2445-KJM-EFB, 2011 WL 2119078 (E.D. Cal. May 26, 2011) (“Sierra Pacific”), interpret Rule 26(a)(2) to provide that a designating party waives privilege—at least in some circumstances—by designating a hybrid non-reporting expert. Other courts, led by Advanced Magnesium Alloys Corp. v. Dery, No. 1:20-cv-02247-RLY-MJD, 2022 WL 16743623 (S.D. Ind. Nov. 7, 2022) (“Dery”), find that the designation of a hybrid witness does not waive otherwise valid privilege claims.

For the reasons that follow, the Court agrees with Ardell that Dery’s reasoning is more applicable to the facts in this case and the Federal Rules governing non-reporting experts. The Court therefore finds that Ardell did not waive attorney-client or work product privileges and denies KISS’s motion to compel.

Id. at *2.

SETTING THE STAGE: FED.R.CIV.P. 26(a)(2)(C)

Because this is a deep dive into a small pool, it may help to set the stage.  Fed.R.Civ.P. 26(a) governs “initial disclosures.”  Rule 26(a)(2)(A) requires expert disclosures.

As the KISS court explained, there are two types of testifying experts, “reporting” and “non-reporting” experts. Id. at *2.  Subsection (B) requires a written report from retained experts, experts who are specially employed to provide expert testimony, or employees who regularly do so.  They are “reporting experts.” Subsection (B) was not at play in KISS.

Subsection (C) governs expert witnesses who are not subject to the reporting requirement, i.e., “non-reporting experts.”  It requires disclosure of “the subject matter” of the expert evidence and “a summary of the facts and opinions on which the witness is expected to testify.”  Subsection (C) was in play in KISS.  Subsection (C) witnesses are sometimes called “hybrid” witnesses. Other times, they are called “non-reporting expert witnesses.”  A classic example of a hybrid expert is a treating physician who will testify to both facts that were personally observed during treatment and expert opinions as a physician. Another example is “employees of a party who do not regularly provide expert testimony.” Id. at *2 (citation omitted).

As the KISS court noted, the scope of required disclosures for Subsection (C) witnesses is different for the two types of experts and it is ambiguous (id. at *4).

Some courts, like the District of Maryland, have Local Rules to provide clarity:

Unless otherwise ordered by the Court, a party must provide the disclosures required by Fed. R. Civ. P. 26(a)(2)(B) only as to experts retained or specially employed by a party to provide expert testimony. The disclosures need not be provided as to hybrid fact/expert witnesses such as treating physicians. The party must disclose the existence of any hybrid fact/expert witness pursuant to Fed. R. Civ. P. 26(a)(2)(A), and disclose the subject matter on which the witness is expected to present evidence under Fed. R. Evid. 702, 703, or 705, as well as a summary of the facts and opinions to which the hybrid fact/expert witness is expected to testify, pursuant to Fed. R. Civ. P. 26(a)(2)(C). In addition, an adverse party may obtain the opinions of such witnesses (to the extent appropriate) through interrogatories, document production requests, and depositions.

104. Md., Local Rule 104.9.

THE DEMARCATION LINE IS NOT CLEAR

Caution and careful discovery planning has been advised: “Although it is clear that a treating physician is the quintessential example of a hybrid witness for whom no Rule 26(a)(2)(B) disclosures are required, it is a mistake to focus solely on the status of the expert, instead of the nature of the testimony which will be offered at trial. A witness can be a hybrid witness as to certain opinions, but a retained expert as to others, and with regard to treating physicians, there is a debate over where the line should be drawn…. The failure to appreciate the distinction between a hybrid witness and retained expert can be a trap for the unwary.”  Sullivan v. Glock, Inc., 175 F.R.D. 497, 500 (D. Md. 1997)(Grimm, J.)(emphasis added).  Additionally, “in distinguishing between pure expert witnesses and hybrid witnesses, Judge Grimm specifically noted the availability of interrogatories to discover the opinions of hybrid witnesses.”  Salvatore v. Benner, 2005 WL 8174320, at *2 (D. Md. June 17, 2005)(Gesner, J.).

THE KISS COURT OPTS FOR PRIVILEGE PROTECTION

In KISS, Ardell’s attorneys had privileged communications with Ms. Cooper, a fact witness. She was a “long-tenured” executive employee and at the time of the communications with counsel, they were privileged.  Because Ms. Cooper was an Ardell employee, there was “no cloak of independence or lack of bias,” like a treating physician may have.  Further, she would be testifying about product specifications and sales based on her personal knowledge. Id. at *7.

The KISS court exhaustively explained the evolution and history of the expert disclosure rules, pointing out that the revisions “did not expressly address protections for non-reporting experts, leaving some ambiguity about whether the designation of a non-reporting expert waives otherwise applicable privileges.” Id. at *4.

The KISS court described the factual and legal issue:

Through this motion, KISS seeks the communications and documents Ms. Cooper reviewed in preparation for her expert testimony in this case…. This information includes, by definition, communications between Ms. Cooper and Ardell’s counsel for the purpose of rendering legal advice in this matter.

Id. at *4.

Based in substantial part on the history of the amendments to the Rules, the court held that Ardell did not waive privilege by designating Ms. Cooper as a hybrid, or non-reporting, expert. Id. It concluded that the 2010 rules amendments did not change prior protections for such experts. It then looked at the principles applicable prior to 2010 and wrote: “KISS cites no cases, and this Court is unaware of any, prior to 2010 in which courts found that a company was found to waive privilege by designating its employee as a non-reporting witness.”  Id. at *7.  The court wrote:

The Court therefore concludes that there is no automatic waiver of privilege where, as here, the witness at issue is an executive employee at the defendant company who was first designated as a fact witness, and then later designated as a non-reporting expert witness, expected to proffer testimony on the same subject matter.

Id. at *8.

The court rejected the argument “that Ardell is improperly using privilege as a ‘sword’ and a ‘shield.’” Id.  However, it provided important clarification:

To be clear, Ardell cannot refuse to disclose the facts on which Ms. Cooper bases her expert opinions…. And given that Ms. Cooper’s testimony appears to be based on her personal knowledge of facts arising prior to this lawsuit, it is unlikely there is any attorney-client or work product protection that applies to the facts underlying her expert testimony. Ms. Cooper’s deposition testimony is consistent with these principles. She answered questions about the content of her expert opinions and the factual basis for them, and only invoked privilege when asked for the substance of communications with counsel.

Id. at *9.  The KISS court’s holding was that Ardell did not waive attorney-client or work product protection “by designating Ms. Coooper as a non-reporting expert under Rule 26(a)(2)(C).”  Id. at *9.  For that reason, it denied KISS’s motion to compel.