Non-Testifying Expert Privilege: Work Product, Confidentiality, and Discovery Risks

A non-testifying expert's work is not automatically privileged. Depending on the jurisdiction and the facts, communications with a consulting expert may be protected by attorney-client privilege, materials may be protected as work product, and the expert's facts or opinions may be subject to separate discovery limits under Federal Rule of Civil Procedure 26. Each doctrine has a different purpose, standard, and potential waiver analysis.

That distinction matters when an attorney retains an expert to analyze technical issues, assess damages, evaluate another expert's work, or help counsel understand a case before deciding whether the expert will testify. Clear planning around consulting vs. testifying expert roles can reduce avoidable disclosure disputes, but it cannot guarantee confidentiality.

Why Protection Questions Require Separate Analyses

Attorneys and litigation teams often use “privilege” as shorthand for several different protections. That shorthand can obscure the issue that will control a particular dispute: whether a communication sought legal advice, whether a document was prepared because of litigation, whether the expert was retained only for consulting, or whether disclosure changed the analysis.

A consulting expert may perform several functions in one engagement. The expert may explain complex medical, engineering, financial, or scientific material to counsel; review records and offer preliminary opinions; gather information; or assist in developing litigation strategy. Courts may examine the purpose and circumstances of each communication or material rather than applying one label to the entire engagement.

• Attorney-client privilege: General Purpose: Protect confidential communications made to obtain or provide legal advice; Key Limitation: Does not ordinarily protect underlying facts merely because they were shared with counsel or a consultant
• Work-product protection: General Purpose: Protect qualifying materials prepared in anticipation of litigation or for trial; Key Limitation: Scope and degree of protection can depend on the material, jurisdiction, and showing made
• Rule 26(b)(4)(D): General Purpose: Limits discovery from certain non-testifying experts retained in anticipation of litigation or trial preparation; Key Limitation: Exceptional circumstances may permit discovery of facts known or opinions held

The analysis may also differ under state law, in federal-question cases, and where a consultant later becomes a testifying expert. Counsel should assess the governing rules before assuming that a consultant's identity, communications, notes, analyses, or source materials will remain protected.

Privilege, Work Product, and Rule 26 Are Not the Same

Attorney-client privilege generally concerns confidential communications made for the purpose of seeking, obtaining, or providing legal advice. When a third-party consultant is involved, a key question is whether the consultant's participation was necessary or useful to counsel's provision of legal advice under the applicable jurisdiction's law. The consultant's independent opinions or ordinary business services are not necessarily privileged simply because counsel requested them.

Work-product protection is distinct. Under Federal Rule of Civil Procedure 26(b)(3), qualifying documents and tangible things prepared in anticipation of litigation or for trial may receive protection. Courts may distinguish between ordinary work product and opinion work product, and state-law standards can differ. The work-product inquiry focuses on the material's preparation and litigation purpose, not solely on whether the material contains a confidential client communication.

Rule 26(b)(4)(D) addresses another question: what discovery is available from an expert retained or specially employed in anticipation of litigation or to prepare for trial who is not expected to testify. Subject to specified exceptions, the rule generally permits discovery of that expert's facts known or opinions held only on a showing of exceptional circumstances under which it is impracticable to obtain facts or opinions on the same subject by other means.

Rule 26's discovery limitation does not itself establish attorney-client privilege or work-product protection. Conversely, the possible application of privilege or work product does not eliminate the need to analyze Rule 26. For a closer discussion of exceptional circumstances and disclosure issues, see our guide to discovery rules for non-testifying experts.

Consultants, Work Product, and Confidentiality

A non-testifying consultant can help counsel test a case theory, interpret specialized evidence, identify questions for a testifying expert, or assess the strengths and weaknesses of an opposing expert's opinions. That role can support a stronger argument for protection when the consultant is engaged as part of counsel's legal work. It does not, however, convert every exchange with the consultant into privileged information.

The relevant facts may include who retained the consultant, the terms of the engagement, the consultant's assigned role, the intended use of the work, and the persons who received communications or materials. Courts may also distinguish communications involving legal advice from those involving technical advice, independent fact development, or services that could have been obtained without the consultant's involvement in counsel's legal analysis.

Confidentiality remains important, but it is not identical to privilege. A confidential engagement agreement may help clarify expectations and the consultant's role. It does not independently create attorney-client privilege, work-product protection, or a Rule 26 discovery limitation.

Agency and Legal-Advice Considerations

The often-cited decision in United States v. Kovel, 296 F.2d 918 (2d Cir. 1961), illustrates why a consultant's function matters. Kovel involved an accountant employed by a law firm to assist attorneys in understanding tax issues. The Second Circuit recognized that an accountant could, in appropriate circumstances, facilitate legal advice in a role analogous to a translator.

The decision is not a blanket rule that communications with experts are privileged. As the court explained, “If what is sought is not legal advice but only accounting service, or if the advice sought is the accountant's rather than the lawyer's, no privilege exists.” The application of this reasoning depends on jurisdiction-specific law and the facts of the engagement.

For a Kovel-type argument, the record may need to show more than counsel's involvement. Relevant considerations can include whether the consultant's participation was connected to counsel's provision of legal advice, whether communications were intended to remain confidential, and whether the consultant acted in a role that helped counsel understand information necessary for legal representation. The precise test and burden vary by jurisdiction.

When Protection May Be Weaker or Unavailable

Protection may be more difficult to establish when a consultant's primary function is independent fact gathering rather than assistance with legal advice or litigation preparation. Underlying facts generally remain discoverable even when a party communicates those facts to counsel or a consultant. A party ordinarily cannot shield otherwise discoverable evidence merely by routing it through an expert.

In U.S. Postal Service v. Phelps Dodge Refining Corp., 852 F. Supp. 156 (E.D.N.Y. 1994), the court addressed privilege issues involving an expert's work based on independently gathered information. The decision is commonly cited for the proposition that an expert's independent fact-gathering and opinions may not receive attorney-client privilege simply because an attorney retained the expert. Its application should be evaluated against the governing law and the specific materials at issue.

Other circumstances that may weaken a protection argument include:

• An unclear or changing expert role, particularly if the consultant is later designated to testify.
• Communications that appear directed to business, technical, or operational advice rather than legal advice.
• Broad circulation of analyses, notes, or reports beyond persons needed for the legal representation.
• Materials created in the ordinary course of business rather than because of anticipated litigation.
• Reliance on information available through other sources without a clear litigation-related purpose.

The 2010 amendments to Rule 26 provided specified protections for draft expert reports and certain attorney-expert communications involving experts required to provide reports. Those provisions primarily concern testifying experts and should not be treated as a universal protection for all consultant communications or materials.

Waiver and Third-Party Disclosure Risks

Disclosure can affect privilege and work-product arguments, but waiver is not governed by a single universal rule. The effect of sharing a document or communication may depend on the nature of the protection asserted, the recipient's relationship to the client and counsel, the disclosure's purpose, applicable common-interest or similar doctrines, and controlling jurisdictional authority.

Teams should therefore consider distribution before circulating consultant materials. Sharing an analysis with insurers, corporate personnel, co-parties, other experts, or outside professionals can create questions about confidentiality, necessity, and waiver. A consultant should not assume that a document marked “privileged” or “confidential” will receive protection; labels may be relevant, but they do not determine the result.

When disclosure is necessary, counsel should evaluate the legal basis for sharing the material, limit recipients to those with a defined role, and document the engagement and communication structure as appropriate. Jurisdiction-specific authority is especially important where the consultant's identity or work may be sought in discovery.

Engagement-Scoping and Documentation Considerations

Thoughtful engagement management can place the legal team in a better position to evaluate and defend asserted protections. Before substantive work begins, counsel may wish to define whether the expert is being retained solely as a consultant, as a possible testifying expert, or for a role that could change as the case develops.

Practical steps may include:

1. Define the consultant's assignment, reporting relationship, and anticipated litigation purpose in the engagement materials.
2. Distinguish consulting work from testifying work where appropriate, particularly if different experts can perform the roles.
3. Establish who may communicate with the consultant and how substantive analyses should be shared.
4. Identify which source materials are discoverable facts, which materials may implicate privilege or work product, and which issues require further legal analysis.
5. Reassess the arrangement if the expert's role changes, if a report will be disclosed, or if the team considers designating the consultant as a witness.

These practices do not guarantee protection, and they should not substitute for research into the governing law. They can, however, make the consultant's role and the purpose of the work easier to assess if a discovery dispute arises. For additional operational guidance, review these considerations for working with a non-testifying expert.

Whether a consulting expert's work is protected depends on the doctrine asserted, the expert's actual function, the materials at issue, the manner of disclosure, and the jurisdiction. Counsel should evaluate privilege, work product, and Rule 26 separately and obtain jurisdiction-specific guidance before relying on any protection.