Expert witness engagement letter: retention terms written for discovery
By Arthur Teboul, DokuTrak · Published
In brief
An expert witness engagement letter sets who retains the expert, whether the role is consulting or testifying, the questions to address, the hourly and testimony fees, and how materials are sent and logged. Write it expecting the other side to read it, because the expert’s pay and the facts provided can be discovered.
The template: Expert witness retention letter
Written for an expert retained by a law firm. Attach the fee schedule as Exhibit A and keep the materials log as Exhibit B. Check the court’s rules for the case before you send it.
- WordEdit the bracketed parts and put it on your letterhead.Free, with your email
- PDFRead-only copy, to print or keep on file.Free, no email
Fill it in online: The engagement letter generator fills this template with your firm and client, keeps the optional clauses you pick, and gives you the letter to copy, print or save.
[Expert name], [credentials] [Expert firm name and address] [Date] [Attorney name] [Law firm name and address] Re: [Case caption], [court], case no. [number]
Dear [Attorney name],
Retention
[Law firm name] retains [expert name] of [expert firm] in the matter above, on behalf of its client [party name], the [plaintiff / defendant]. [Party name] is responsible for our fees, and [Law firm name] guarantees their payment.
Role
We are retained as a [consulting expert / testifying expert]. If you later wish us to testify, you will confirm that in writing, and the terms of this letter will continue to apply.
Questions to address
You have asked us to consider: [question 1]; [question 2]. Our opinions will be our own, based on our analysis of the evidence, and we make no promise about what they will be.
Conflicts
We have checked the parties and counsel you listed and found [no conflict / the following prior work, disclosed to you: (description)]. We will tell you promptly if we learn of any new conflict during the case.
Materials
You will send us the pleadings, discovery responses, deposition transcripts, records and data we need, in writing, by [dates]. Please state in writing any facts or assumptions you ask us to rely on. We will keep a dated log of everything we receive (Exhibit B).
Report
If a written report is required, we will deliver it by [date], provided the materials arrive by [date]. It will include our opinions and their basis, the facts and data we considered, exhibits, our qualifications and publications, prior testimony, and our compensation.
Fees
Our rates are in Exhibit A: [rate] per hour for review, analysis and report writing; [rate] per hour for deposition and trial testimony, with a minimum of [hours] per testimony day; travel at [rate]. Expenses are billed at cost.
Retainer
A retainer of [amount] is due before we begin. We will apply it to our final invoice. Invoices are due within [number] days; we may stop work, other than testimony already scheduled, while an invoice is more than [number] days overdue.
Opposing party’s deposition
We will invoice the party taking our deposition for our time attending it, and for any preparation time the court allows. [Law firm name] will pay any balance, and will pay the whole invoice if that party has not paid within [number] days, then seek reimbursement.
No outcome-based fees
Our fees do not depend in any way on our findings, on the content of our opinions or on the outcome of the case.
Cancellation and postponement
If a deposition or trial day we have reserved is cancelled or postponed less than [number] business days ahead, we will bill [hours] for each reserved day.
Confidentiality and return of materials
We will keep all case materials confidential, follow any protective order you send us, and return or destroy them at your request after the case and any appeals end, keeping only what our professional standards require.
Ending the engagement
Either of us may end this engagement in writing. Fees are due through the end date. We may withdraw if asked to change an opinion we do not hold, or if a conflict arises that we cannot resolve.
Liability and governing law(optional)
Our total liability for any claim about this engagement is limited to the fees paid to us, except where the law does not allow such a limit. This letter is governed by the laws of [state], and any dispute between us will first go to non-binding mediation in [city, state].
Acceptance
Please sign below, and have [party name] sign as the party responsible for fees, then return a copy with the retainer.
Sincerely, [Expert name], [credentials] Signature: ____________________ Date: __________ Retaining attorney: [Attorney name], [Law firm name] Signature: ____________________ Date: __________ Responsible party: [Party name] Signature: ____________________ Date: __________
Who retains the expert, and in what role
Experts are often retained by the law firm, not by the party. That keeps the work inside the lawyer’s trial preparation. It also gives one place, the law firm, for every request, such as a new data set or a change in deadline. The letter can still name the party as the one who pays, and the lawyer’s firm as a guarantor if the party does not.
Name the role on day one. A consulting expert is one retained to advise the legal team who is not expected to testify. The other side usually cannot discover what this expert knows or thinks (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). A testifying expert is one the party plans to call, who must usually give a written report. Say in the letter that a move from one role to the other is confirmed in writing.
List the questions the lawyer wants answered, for example “the lost profits of the plaintiff from [date] to [date]”. Then add a sentence that the expert’s opinion will be the expert’s own, whatever it turns out to be.
What the report must contain, and what the other side sees
In federal court, a retained testifying expert’s report must include the items below (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). Build the letter so each item has an owner and a source, especially the last one: the report states what the expert is paid.
| Report item under Rule 26 | What the letter does about it |
|---|---|
| All opinions, with the basis and reasons | Sets the questions and the expert’s independence |
| Facts or data considered | Requires a log of every item the lawyer sends |
| Exhibits used to support the opinions | Sets who prepares and pays for exhibits |
| Qualifications and publications of the previous 10 years (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery) | Expert sends a current CV with the list |
| Cases testified in during the previous 4 years (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery) | Expert keeps the list current |
| Compensation for study and testimony | Fee schedule attached as an exhibit |
Drafts, emails and the materials log
Draft reports are protected from discovery in federal court, and so are most communications between the lawyer and a reporting expert (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). Three kinds are not: those about the expert’s pay, those that identify facts or data the lawyer gave the expert, and those that identify assumptions the lawyer asked the expert to rely on (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery).
That shapes the letter. Keep the fee terms in the letter and its exhibit, which you expect to produce. Send facts and assumptions in writing, numbered. Then have the expert keep a log. A materials log is a dated list of every document and data set the expert receives. State courts follow their own rules, so check them when the case is not in federal court.
Rates, retainers and the other side’s deposition
Write separate rates for review, report writing, deposition and trial. Add travel time and a minimum charge for a testimony day. Add a fee for reserved days cancelled late. Experts block those days, and a late cancellation leaves them unpaid. A retainer is applied to the final invoice, or kept at a set level and topped up.
When the other side deposes your expert, the court must generally require the party seeking discovery to pay the expert a reasonable fee for that time (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). The rule speaks of time spent responding to discovery, so a court may not order the other side to pay for preparation time (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). The letter should say who bills that time and who pays if the other side is slow to pay. Ask the retaining firm to guarantee it.
Fees must never depend on the outcome. For CPA experts the rule is explicit: a member engaged as an expert witness may not give opinions under a contingent fee arrangement unless the AICPA contingent fee rule allows it (AICPA Statement on Standards for Forensic Services No. 1). A CPA expert also may not give an opinion on the ultimate conclusion of whether fraud occurred, which is for the trier of fact (AICPA Statement on Standards for Forensic Services No. 1).
Conflicts, independence and admissibility
Run a conflict check on every party and law firm before signing, and keep the duty to disclose new conflicts running. CPA experts face one more bar. Expert witness services for an attest client impair independence, because they look like advocacy for that client (AICPA Code of Professional Conduct, ET 1.295.140, Forensic Accounting).
Admissibility drives the scope too. Federal Rule of Evidence 702 sets the test (Federal Rules of Evidence (December 1, 2024), Rule 702, Testimony by Expert Witnesses). The party offering the expert must show it is more likely than not that the testimony rests on enough facts or data (Federal Rules of Evidence (December 1, 2024), Rule 702, Testimony by Expert Witnesses). It must also come from reliable methods, applied reliably to the case (Federal Rules of Evidence (December 1, 2024), Rule 702, Testimony by Expert Witnesses). Put a clause in the letter that the lawyer will tell the expert promptly of any challenge to the method.
Questions people ask
Is an expert witness engagement letter discoverable?
Often, in part. Federal rules protect most lawyer-expert communications but not those about compensation, facts or data provided, or assumptions provided (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery). Write the letter as if the other side will read it.
Can an expert witness be paid on a contingency basis?
An outcome-based fee invites an attack on the expert’s independence. For CPAs, the AICPA forensic standard bars giving expert opinions under a contingent fee arrangement unless its contingent fee rule allows it (AICPA Statement on Standards for Forensic Services No. 1).
Who pays the expert for a deposition by the other side?
In federal court, unless manifest injustice would result, the court must require the party seeking discovery to pay the expert a reasonable fee for time spent responding (Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery).
Should the attorney or the client retain the expert?
Often the attorney, so the work stays part of trial preparation. The letter can make the client responsible for fees and the firm a guarantor.
Sources
- Federal Rule of Civil Procedure 26, Duty to Disclose; General Provisions Governing Discovery: Contents of a retained expert’s report, protection of drafts and of lawyer-expert communications with three exceptions, limits on discovery of consulting experts, and payment for deposition time.
- Federal Rules of Evidence (December 1, 2024), Rule 702, Testimony by Expert Witnesses: The proponent must show it is more likely than not that expert testimony helps the trier of fact, rests on sufficient facts or data and reliable methods, reliably applied.
- AICPA Code of Professional Conduct, ET 1.295.140, Forensic Accounting: Providing expert witness services for an attest client impairs independence because of the advocacy threat.
- AICPA Statement on Standards for Forensic Services No. 1: A member engaged as an expert witness may not give opinions under a contingent fee arrangement unless the contingent fees rule allows it, and may not opine on the ultimate conclusion of fraud.
About the author
Arthur Teboul (Founder, DokuTrak) is building DokuTrak after watching professionals lose hours chasing clients for documents over email. Arthur Teboul.
Editorial standards
How this page was made (methodology): it is built from the primary sources listed under Sources, and every rule and figure on it links to the source it comes from. Last updated October 25, 2026. Spotted an error or a rule that changed? Contact us.
Ask once. DokuTrak does the chasing.
- Your client uploads from one link, with no account and no password.
- Reminders go out on a schedule, by default 2, 5, 10 and 14 days after the request, until the file arrives.
- With AI review switched on in your workspace (it is off by default), each upload gets a first pass that flags a file that is not the requested document or an unreadable or blurry scan. It says so when it is not sure.
- You accept every file or mark it for re-upload, and your client gets the note by email. The AI never accepts a file.