Rule 1.508.Discovery of experts

Division V: Discovery and Inspection · Last amended January 1, 2015 · Last verified July 15, 2026

In one sentenceRule 1.508 sets separate rules for discovering an expert's opinions and materials: deposing a testifying expert only after any required report is produced, protecting draft reports and most attorney-expert communications as trial-preparation material, and requiring the side that wants the discovery to pay the expert a reasonable fee for the time it takes.

Full Text of Rule 1.508

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1.508(1) Expert who is expected to be called as a witness. In addition to the disclosures and discovery provided pursuant to rules 1.500(2) and 1.516, discovery of facts known, mental impressions, and opinions held by an expert whom the other party expects to call as a witness at trial, otherwise discoverable under the provisions of rule 1.503(1) and acquired or developed in anticipation of litigation or for trial, may be obtained as follows:

a. Deposition of an expert who may testify. A party may depose any person who has been identified as an expert whose opinions may be presented at trial. If rule 1.500 (2)(b) requires a report from the expert, the deposition may be conducted only after the report is provided.

b. Discovery by other means. Subject to rules 1.508 (1)(d) and (e), a party may also obtain discovery of documents and tangible things including all tangible reports, physical models, compilations of data, and other material prepared by an expert or for an expert in anticipation of the expert's trial and deposition testimony. The disclosure of material prepared by an expert used for consultation is required even if it was prepared in anticipation of litigation or for trial when it forms a basis, either in whole or in part, of the opinions of an expert who is expected to be called as a witness.

c. Tangible form. Subject to rules 1.508 (1)(d) and (e), if the discoverable factual observations, tests, supporting data, calculations, photographs, or opinions of an expert who will be called as a witness have not been recorded and reduced to tangible form, the court may order these matters be reduced to tangible form and produced within a reasonable time before the date of trial.

d. Trial preparation protection for draft reports or interrogatory answers. Rule 1.503 (3) protects drafts of any report or disclosure required under rule 1.500 (2), regardless of the form in which the draft is recorded.

e. Trial preparation protection for communications between a party's attorney and expert witnesses. Rule 1.503 (3) protects communications between the party's attorney and any witness required to provide a report under rule 1.500 (2)(b), regardless of the form of the communications, except to the extent that the communications:

(1) Relate to compensation for the expert's study or testimony.

(2) Identify facts or data that the party's attorney provided and that the expert considered in forming the opinions to be expressed.

(3) Identify assumptions that the party's attorney provided and that the expert relied on in forming the opinions to be expressed.

(2) Expert who is not expected to be called as a witness. The disclosure of the same information concerning an expert used for consultation and who is not expected to be called as a witness at trial is required if the expert's work product forms a basis, either in whole or in part, of the opinions of an expert who is expected to be called as a witness. Otherwise, a party may discover the identity of and facts known, or mental impressions and opinions held, by an expert who has been retained or specially employed by another party in anticipation of litigation or preparation for trial and who is not expected to be called as a witness at trial, only as provided in rule 1.516 or upon a showing of exceptional circumstances under which it is impracticable for the party seeking discovery to obtain facts or opinions on the same subject by other means.

(3) Duty to supplement discovery as to experts. For an expert whose report must be disclosed under rule 1.500 (2)(b), the party's duty to supplement extends both to information included in the report and to information given during the expert's deposition. Any additions or changes to this information must be disclosed no later than 30 days before trial. Failure to disclose or supplement the identity of an expert witness or the information described in rule 1.500 (2) is subject to sanctions under rule 1.517 (3)(a).

(4) Expert testimony at trial. The expert's direct testimony at trial may not be inconsistent with or go beyond the fair scope of the expert's disclosures, report, deposition testimony, or supplement thereto.

(5) Expert fees during discovery. Unless manifest injustice would result, the court shall require that the party seeking discovery pay the expert a reasonable fee for time spent in responding to discovery under rules 1.508 (1) and 1.508 (2). With respect to discovery obtained under rule 1.508 (1), the court may require, and with respect to discovery obtained under rule 1.508 (2), the court shall require the party seeking discovery to pay the other party a fair portion of the fees and expenses reasonably incurred by the latter party in obtaining facts and opinions from the expert. Any fee which the court requires to be paid shall not exceed the expert's customary hourly or daily fee; and, in connection with a party's deposition of another party's expert, shall include the time reasonably and necessarily spent in connection with such deposition, including time spent in travel to and from the deposition, but excluding time spent in preparation.

(6) Effective date. Rules 1.508 (1)(a), 1.508 (d), 1.508 (1)(e), and 1.508 (3) apply only to actions commenced on or after January 1, 2015, provided that the court may in any case direct the parties to comply with all or part of the rules as part of a pretrial order.

End

Plain-English Summary

Rule 1.508(1) covers experts the other side expects to call as a witness. Beyond the disclosures Rules 1.500(2) and 1.516 already require, a party can depose any expert identified as a possible trial witness, though if Rule 1.500(2)(b) requires a written report from that expert, the deposition can only happen after the report is produced. A party can also obtain documents and tangible things — reports, models, data compilations — the expert prepared, and even material a consulting expert prepared can come out if it forms any part of a testifying expert's opinions. If an expert's factual observations, tests, or opinions were never reduced to tangible form, the court can order that done and the material produced a reasonable time before trial.

The rule also protects certain material from discovery. Draft reports or draft disclosures stay protected as trial-preparation material regardless of the form they're recorded in, and so do communications between a party's attorney and any expert required to provide a report, with three narrow exceptions: information about the expert's compensation, facts or data the attorney gave the expert that the expert considered in forming opinions, and assumptions the attorney gave the expert that the expert relied on.

Rule 1.508(2) covers experts a party consulted but doesn't expect to call as a witness. Their identity and opinions are generally off-limits, unless that expert's work underlies a testifying expert's opinions, or the requesting party shows exceptional circumstances making it impracticable to get the same facts or opinions any other way. Rule 1.508(3) requires supplementing expert discovery, both the report and the deposition testimony, no later than 30 days before trial, with sanctions available under Rule 1.517(3)(a) for failing to do so. Rule 1.508(4) keeps an expert's trial testimony within the fair scope of the disclosures, report, deposition, and any supplement already provided. And Rule 1.508(5) requires, unless it would work manifest injustice, that the party seeking expert discovery pay the expert a reasonable fee for the time spent responding, plus — mandatorily for certain non-testifying-expert discovery and at the court's discretion for testifying-expert discovery — a fair share of the other side's own fees and expenses in producing that testimony, capped at the expert's customary rate and covering deposition travel time but not preparation time. Several of these provisions, including the deposition-before-report sequencing and the supplementation deadline, apply only to actions commenced on or after January 1, 2015, though a court can direct any case to follow them.

Frequently Asked Questions

Can I depose the other side's expert before I've received the expert's written report?

Not if Rule 1.500(2)(b) requires a report from that expert. Rule 1.508(1)(a) states the deposition may be conducted only after the report is provided.

Are draft expert reports protected from discovery?

Yes. Rule 1.508(1)(d) protects drafts of any report or disclosure required under Rule 1.500(2), regardless of the form the draft is recorded in.

Can I discover the opinions of a consulting expert who won't testify at trial?

Generally only if that expert's work underlies a testifying expert's opinions, or if you can show exceptional circumstances making it impracticable to obtain the same facts or opinions from any other source.

How late before trial must expert discovery be supplemented?

No later than 30 days before trial, covering both the report and any information given during the expert's deposition, under Rule 1.508(3).

Who pays the expert's fee when I take that expert's deposition?

Unless it would cause manifest injustice, you must pay the expert a reasonable fee for the time spent responding to your discovery, and the court may also require you to pay the other party a fair portion of its own fees and expenses in producing that expert's testimony.

Source & verification. Rule text and the Comment are reproduced verbatim from the Iowa Rules of Civil Procedure, adopted by the Iowa Supreme Court. Last verified July 15, 2026. · Official source

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