Expert Engagement Letters

Why the letter exists before the work does

An expert engagement letter is a commercial contract that also allocates litigation risk, and it is written before any privileged material reaches the expert because two of its clauses only work if they precede the work. The designation clause determines whether the expert's analysis is protected. The conflicts clause determines whether the analysis can be used at all.

In an earlier edition of SEAK's expert fee survey, 47 percent of responding experts reported requiring a signed retention agreement before starting work, and 66 percent in the 2021 edition reported requiring a written retention agreement at all. Which is a way of saying that a substantial share of expert engagements in this market begin without one, on an exchange of emails, and that the terms are then reconstructed after a dispute about a canceled trial date or an unpaid invoice.

The letter is also the document that answers questions a court will later ask about the relationship. Whether a confidential relationship existed with a candidate, what the compensation arrangement was, and whether the expert was retained by counsel or by the party are all facts the letter fixes contemporaneously and nothing else does.

Designation, and who the client is

Consulting or testifying, stated expressly. The discovery consequences diverge sharply. FRCP 26(b)(4)(D) ordinarily shields facts known and opinions held by an expert retained or specially employed in anticipation of litigation who is not expected to testify, subject to Rule 35(b) and to a showing of “exceptional circumstances under which it is impracticable for the party to obtain facts or opinions on the same subject by other means.” A testifying expert, by contrast, produces a report under FRCP 26(a)(2)(B) disclosing the facts or data considered, the qualifications, the prior testimony list and the compensation.

The clause should also address what happens if the designation changes. Converting a consultant into a testifying witness mid-case should be assumed to expose everything that consultant touched on the subject of the testimony, and the practitioner literature describes using the same firm in both roles as playing with fire.

Retention by counsel or by the party. This is not a formality. Retention by counsel is the practice recommended for preserving the consulting-expert protection, and it also determines who the expert can pursue for payment. Authority on whether the retaining attorney is personally liable when the client does not pay is split by state and turns largely on whether the agency was disclosed. Attorneys were held liable in McCullough v. Johnson, 816 S.W.2d 886 (Ark. 1991), which stated that an attorney ordering goods or services will be personally liable in the absence of an express disclaimer, in Copp v. Breskin, 782 P.2d 1104 (Wash. Ct. App. 1989), and in Theuerkauf v. Sutton, 306 N.W.2d 651 (Wis. 1981). Attorneys or their firms were not liable where the agency was disclosed in Free v. Wilmar J. Helric Co., 688 P.2d 117 (Or. Ct. App. 1984) and Eppler, Guerin & Turner, Inc. v. Kasmir, 685 S.W.2d 737 (Tex. Ct. App. 1985). An express clause naming who owes the money makes the question academic.

Scope, and what is outside it

The scope clause states the questions the expert is being asked and, more usefully, the questions the expert is not being asked. An expert asked to opine on causation who volunteers a view on damages has created a disclosure problem, an exposure at deposition, and often a bill nobody authorized.

Scope also governs the materials. The letter should record what is being supplied and by whom, and should require the expert to keep a record of everything reviewed — a discipline that costs nothing during the engagement and is expensive to reconstruct at a deposition where the question is what the witness considered.

Confidentiality belongs in the same part of the letter: that the retention itself is confidential; that the expert will not disclose the engagement without written permission; that materials are labeled as privileged and confidential attorney work product; and that any protective order in the case binds the expert and the expert's assistants.

The money terms, and the ones that actually decide the bill

The headline hourly figure is the least interesting term in this section. What decides the cost of an engagement is everything around it.

• Rates by activity. Separate figures for review, deposition and trial are the market norm, and every published dataset shows testimony priced above review.
• Assistants. Named, with their own figures, or the invoice will contain work nobody agreed to.
• Retainer. The amount, and crucially whether it replenishes. An evergreen retainer must be topped back up to a floor as it is drawn down; a simple deposit is applied against early invoices until exhausted. Model letters in adjacent professions offer several alternative formulations of this clause, which is a signal that it is a drafting choice rather than a default.
• Invoicing cadence. Monthly is the recommended default, so that spend is visible as it accrues rather than arriving as one number after the report.
• Expenses and travel, including whether travel time is billed and at what proportion of the working figure.
• Minimums. Roughly a third of experts in the SEAK series impose a minimum billable amount for depositions and a similar share for trial. Half-day and full-day minimums are the common forms.
• Cancellation. Slightly over half of responding experts in that series reported a policy retaining all or part of an appearance charge where notice falls inside a stated window. Trial dates move; the window is the term that matters.
• Late payment. Interest or a surcharge, if any.

Two of those terms — the minimum and the cancellation window — account for most of the disputes that arise between counsel and a retained expert, because they are the terms that bill for work that was not done.

No contingency, and why it is stated expressly

Compensation for a testifying expert is for time, not for outcome, and the letter should say so in terms. The governing ethics text is a comment rather than black-letter rule. ABA Model Rule 3.4(b) provides that a lawyer shall not “falsify evidence, counsel or assist a witness to testify falsely, or offer an inducement to a witness that is prohibited by law.” Comment [3] supplies the content: “With regard to paragraph (b), it is not improper to pay a witness's expenses or to compensate an expert witness on terms permitted by law. The common law rule in most jurisdictions is that it is improper to pay an occurrence witness any fee for testifying and that it is improper to pay an expert witness a contingent fee.”

Read the phrasing carefully. The Model Rules describe the contingent-fee bar as the common law rule in most jurisdictions; they do not themselves enact it. The operative prohibition is whatever the forum jurisdiction has adopted, and state ethics opinions apply it directly — Alabama State Bar Formal Opinion RO-1997-02, for instance, permits a reasonable and customary fee for preparing and providing expert testimony but not a fee contingent on the outcome of the proceeding.

Federal authority is to the same effect. In Accrued Financial Services, Inc. v. Prime Retail, Inc., 298 F.3d 291 (4th Cir. 2002), where a lease-auditing company took assignments of tenants' claims in exchange for a share of any recovery and its employees were to testify as experts, the court held that the company “was offering expert testimony for a contingent fee” and that “[s]uch an arrangement would also violate public policy,” reasoning that financial arrangements providing incentives for the falsification or exaggeration of testimony threaten the integrity of a judicial process that depends on the truthfulness of witnesses.

What follows from a contingent arrangement is less settled. District courts have excluded the testimony — Straughter v. Raymond (C.D. Cal. 2011), J & J Snack Foods Corp. v. Earthgrains Co., 220 F. Supp. 2d 358 (D.N.J. 2002), Farmer v. Ramsay, 159 F. Supp. 2d 873 (D. Md. 2001) — while Tagatz v. Marquette University, 861 F.2d 1040 (7th Cir. 1988), treated it as a credibility matter for the jury. The practical point for the letter is that an express statement that compensation is for time also gives the witness a clean answer at trial: the compensation is for the time spent on the case rather than for supplying a paid opinion.

Conflicts, documents and how it ends

Conflicts. An affirmative representation that the expert has disclosed prior assignments and prior published positions bearing on the matter, plus a continuing duty to notify counsel immediately of any conflict arising later and of any subpoena received in another matter. Engagements run for years and the expert's client list does not stand still.

Document handling. That the expert keeps a record of everything reviewed; that drafts, notes and correspondence should be treated as potentially discoverable; and that materials are returned or destroyed at the end of the engagement. The federal protections for draft reports and attorney–expert communications under FRCP 26(b)(4)(B) and (C) took effect on 1 December 2010, but several states did not adopt them, so in those courts drafts and correspondence remain discoverable. A letter that assumes the federal position is wrong in a state case.

Termination. How either side ends the engagement, what happens to work in progress, and what happens to any unearned portion of the retainer.

Post-engagement obligations. Continuing confidentiality and continuing compliance with any protective order, both of which survive the end of the assignment.

The clause the other side gets to read

There is an asymmetry in this document that shapes how it should be drafted. Most of what passes between counsel and a testifying expert is protected: since 1 December 2010, FRCP 26(b)(4)(B) protects drafts of any report or disclosure required under Rule 26(a)(2) regardless of the form in which the draft is recorded, and FRCP 26(b)(4)(C) protects attorney–expert communications. But the protection has three carve-outs, and the first is compensation: communications are unprotected to the extent they “relate to compensation for the expert's study or testimony.” FRCP 26(a)(2)(B)(vi) then requires the compensation to be stated in the report itself.

So the fee terms in an engagement letter are among the very few things about the attorney–expert relationship that the rules leave open to the other side. They should be written to be read by an adversary: an activity-differentiated schedule, ordinary retainer and minimum terms, and nothing that looks like a premium attached to the content of the opinion or to the outcome of the case.

The same instinct applies to the negotiation. Anything said in the course of agreeing compensation is outside the protection, which is a reason to keep that correspondence separate from correspondence about the substance of the opinion, and a reason not to conduct both in the same email thread.

Frequently Asked Questions

Published 2026-08-12