What are the disclosure rules under Rule 26 in federal court?

Federal Rule 26 disclosures

In federal civil cases, Fed. R. Civ. P. 26 requires certain information to be exchanged without waiting for a discovery request. The deadlines in the Rule are defaults: a scheduling order, stipulation, or case-specific court order may change them, so the case’s scheduling order and applicable district-court local rules should be checked first.[2]

1. Initial disclosures

Unless the case is exempt or the court or parties provide otherwise, each party must disclose information it may use to support its claims or defenses, other than information used solely for impeachment. The disclosures generally include:

• People with relevant information: their names and, if known, contact information, plus the subjects of their knowledge.
• Documents and other materials: copies, or a description by category and location, of responsive materials in the party’s possession, custody, or control.
• Damages: a computation of each category of damages claimed and the supporting materials.
• Insurance: applicable insurance agreements.

The default deadline is within 14 days after the parties’ Rule 26(f) conference, unless a different deadline applies. A party joined after that conference generally has 30 days after service or joinder. Initial disclosures are based on information reasonably available; an incomplete investigation or an opposing party’s failure to disclose is not, by itself, an excuse for failing to disclose.[2]

Certain proceedings—including actions for review on an administrative record and specified habeas or prisoner actions—are exempt from initial disclosures under the Rule. A party that believes initial disclosures are inappropriate in the case may raise that issue at the Rule 26(f) conference and include the objection in the discovery plan; the court decides what, if anything, must be disclosed.[2]

2. Expert disclosures

A party must identify each witness it may use at trial to provide expert testimony. The required disclosure depends on the expert’s role:

The scheduling order controls the timing. If it does not set a deadline, disclosures generally are due at least 90 days before trial; a disclosure intended solely to rebut another party’s expert is generally due within 30 days after that disclosure.[2] A treating physician is not automatically exempt from expert disclosure: the nature of the expected testimony matters. A treating physician offering opinions formed during treatment ordinarily does not need a full retained-expert report, but the required summary disclosure still applies.[1]

3. Pretrial disclosures

At least 30 days before trial, unless the court orders otherwise, parties generally must identify the witnesses they expect to present or may call if needed, deposition testimony they expect to use, and exhibits they may offer. A party generally has 14 days after those disclosures to identify specified objections to deposition use or exhibit admissibility; failure to list an objection may waive it, subject to the Rule’s exceptions and the court’s authority.[2]

4. Supplementation

A party must timely supplement or correct a disclosure or discovery response when it learns that the information is materially incomplete or incorrect and the correction has not otherwise been made known in discovery or in writing. For a report-required expert, that duty includes changes to the report or deposition testimony; expert additions or changes must be disclosed by the time pretrial disclosures are due.[2]

5. Rule 26(f) planning and privilege issues

The parties generally must confer as soon as practicable and at least 21 days before the scheduling conference or the date a scheduling order is due. Their discovery plan addresses subjects and timing of discovery, electronically stored information, preservation, and privilege or work-product issues. Under the Rule’s 2025 amendment, the plan should address how the parties will comply with the requirement to describe materials withheld on privilege or trial-preparation grounds, including any proposed method for doing so.[3]

6. Consequences of nondisclosure

Under Fed. R. Civ. P. 37(c)(1), a party that fails to disclose or supplement as required generally may not use the undisclosed information or witness on a motion, at a hearing, or at trial—unless the failure was substantially justified or harmless. The court may also impose other sanctions. In the Ninth Circuit, the party facing exclusion bears the burden of showing that the failure was substantially justified or harmless; exclusion may be upheld even when it significantly impairs a party’s case.[4][5] The Ninth Circuit has also affirmed exclusion where expert disclosures were repeatedly late or incomplete and the party did not establish justification or harmlessness.[1]

Practical point: Treat the scheduling order as the controlling calendar, identify each witness’s role before deciding what expert disclosure is required, and supplement promptly when material information changes. A missed disclosure deadline can affect whether evidence may be used later.