Federal expert disclosures: 90 days before trial, and two very different kinds of expert

Rule 26(a)(2) splits experts into two categories with very different disclosure burdens, and the distinction turns on the witness's relationship to the case rather than on what they will say.

The deadlines

Rule 26(a)(2)(D): a party must make these disclosures at the times and in the sequence the court orders. Absent a stipulation or court order, the disclosures must be made:

(i) at least 90 days before the date set for trial or for the case to be ready for trial; or (ii) if the evidence is intended solely to contradict or rebut evidence on the same subject matter identified by another party under Rule 26(a)(2)(B) or (C), within 30 days after the other party's disclosure.

In practice the scheduling order almost always sets different dates, and it controls. The 90/30 default matters most when the order is silent or when a case is proceeding without one.

Note what (ii) requires: the rebuttal must be solely to contradict or rebut, and on the same subject matter. A "rebuttal" report that advances affirmative opinions isn't within the 30-day branch.

Who must be disclosed at all

Rule 26(a)(2)(A): in addition to the Rule 26(a)(1) disclosures, a party must disclose "the identity of any witness it may use at trial to present evidence under Federal Rule of Evidence 702, 703, or 705."

That covers anyone giving opinion testimony as an expert — including a treating physician or a company engineer — not only a hired consultant.

Category one: witnesses who must provide a written report

Rule 26(a)(2)(B): unless stipulated or ordered otherwise, the disclosure must be accompanied by a written report prepared and signed by the witness if the witness is either:

• retained or specially employed to provide expert testimony in the case, or
• one whose duties as the party's employee regularly involve giving expert testimony.

The report must contain:

(i) a complete statement of all opinions the witness will express and the basis and reasons for them; (ii) the facts or data considered by the witness in forming them; (iii) any exhibits that will be used to summarize or support them; (iv) the witness's qualifications, including a list of all publications authored in the previous 10 years; (v) a list of all other cases in which, during the previous 4 years, the witness testified as an expert at trial or by deposition; and (vi) a statement of the compensation to be paid for the study and testimony in the case.

Two of those are commonly under-supplied. "All opinions" means the report is the outer boundary of the testimony — an opinion not in it is vulnerable under Rule 37(c)(1). And "the facts or data considered" is broader than the facts relied upon; it reaches material the expert reviewed and rejected.

Category two: witnesses who do not provide a report

Rule 26(a)(2)(C): if the witness is not required to provide a written report, the disclosure must state:

• (i) the subject matter on which the witness is expected to present evidence under Rule of Evidence 702, 703, or 705; and
• (ii) a summary of the facts and opinions to which the witness is expected to testify.

This is the provision for treating physicians, employees who did not regularly give expert testimony, and similar witnesses. It is much lighter than a Rule 26(a)(2)(B) report — but it is a real, affirmative obligation, and the most common expert-disclosure failure in federal practice is producing nothing at all for a (C) witness on the assumption that no report means no disclosure.

What the other side may discover

Rule 26(b)(4)(A): a party may depose any person identified as an expert whose opinions may be presented at trial. If a Rule 26(a)(2)(B) report is required, the deposition may be conducted only after the report is provided.

Draft reports are protected. Rule 26(b)(4)(B): drafts of any report or disclosure required under Rule 26(a)(2) are protected as trial-preparation material, "regardless of the form in which the draft is recorded."

Attorney–expert communications are mostly protected. Rule 26(b)(4)(C): communications between a party's attorney and a Rule 26(a)(2)(B) expert are protected regardless of form, except to the extent they:

• relate to compensation for the expert's study or testimony;
• identify facts or data the attorney provided and that the expert considered in forming the opinions; or
• identify assumptions the attorney provided and that the expert relied on.

Those three exceptions are the entire discoverable surface of the attorney–expert relationship, and they are narrower than the pre-2010 practice they replaced.

Non-testifying experts. Rule 26(b)(4)(D): a party may not, by interrogatories or deposition, discover facts known or opinions held by an expert retained in anticipation of litigation who is not expected to testify, except as Rule 35(b) provides or "on showing exceptional circumstances under which it is impracticable for the party to obtain facts or opinions on the same subject by other means."

Fees. Rule 26(b)(4)(E): unless manifest injustice would result, the court must require the party seeking discovery to pay the expert a reasonable fee for time spent responding, and — for discovery under (b)(4)(D) — a fair portion of the fees and expenses the other party reasonably incurred in obtaining the expert's facts and opinions.

Supplementation, and the sanction

Rule 26(a)(2)(E): the parties must supplement expert disclosures when required under Rule 26(e).

Rule 26(e)(2) sets the timing for a Rule 26(a)(2)(B) expert: the duty extends both to information in the report and to information given during the expert's deposition, and any additions or changes must be disclosed by the time the party's pretrial disclosures under Rule 26(a)(3) are due — that is, 30 days before trial.

Rule 37(c)(1) supplies the consequence for getting any of this wrong:

If a party fails to provide information or identify a witness as required by Rule 26(a) or (e), the party is not allowed to use that information or witness to supply evidence on a motion, at a hearing, or at a trial, unless the failure was substantially justified or is harmless.

Exclusion is the default. It operates without a prior court order, which makes it closer in effect to a deemed admission than to the rest of Rule 37.

Physical and mental examinations

A related route: Rule 35(a) allows the court, on motion for good cause and on notice, to order a party — or a person in a party's custody or legal control — to submit to a physical or mental examination by a suitably licensed or certified examiner. The order must specify the time, place, manner, conditions and scope, and the person who will perform it.

Rule 35(b) governs the examiner's report, the requesting party's obligation to deliver it on request, and the waiver of privilege that follows.

The sequence in a typical case

A short checklist

1. Read the scheduling order first. The 90/30 defaults yield to it.
2. Decide which category each witness is in. Retained or regularly-testifying employee means a full Rule 26(a)(2)(B) report; everyone else needs a (C) disclosure — but still needs one.
3. Put every opinion in the report. Rule 37(c)(1) excludes what you leave out.
4. **Disclose facts or data *considered***, not just relied on.
5. Keep the 10-year publication list and 4-year testimony list current — these are the most commonly omitted report elements.
6. Rebuttal must be solely rebuttal, on the same subject matter.
7. Supplement by the pretrial disclosure date, including changes to deposition testimony.

Where these rules live

• Rule 16 — Pretrial Conferences; Scheduling; Management
• Rule 26 — Duty to Disclose; General Provisions Governing Discovery
• Rule 30 — Depositions by Oral Examination
• Rule 35 — Physical and Mental Examinations
• Rule 37 — Failure to Make Disclosures or to Cooperate
• Rule 56 — Summary Judgment

Admissibility is governed by the Federal Rules of Evidence, which this site doesn't publish. This page explains what the civil rules say. It isn't legal advice.