Supplementing Disclosures

A disclosure can be accurate on the day it is served and wrong a month later. Rule 26(e) answers that problem by making a party’s disclosures and discovery responses a continuing obligation instead of a one-time act.¹ A party that has made a Rule 26(a) disclosure, or has answered an interrogatory, a request for production, or a request for admission, must supplement or correct it in a timely manner once it learns that the earlier version is incomplete or incorrect in some material respect and the opponent does not already have the corrective information.² The obligation also reaches expert disclosures, because the expert-disclosure rule directs the parties to supplement them whenever Rule 26(e) requires.³

The duty exists because of how early the first disclosures come. Initial disclosures are due at or within 14 days after the Rule 26(f) conference,⁴ so the first version will sometimes fall behind what the party later learns. Without a duty to update, that early deadline would favor the disclosing party. It could meet the deadline with a short witness list, learn of an important witness a month later, and say nothing, leaving its opponent to plan depositions around a picture the party knew was out of date. Rule 26(e) puts the burden on the side that holds the new information.

Three questions organize the rest of the unit: when a party must update, what added rule governs experts who must report, and what a party loses by staying silent.

The Duty to Supplement

Rule 26(e)(1) names two kinds of material that a party must keep current. The first is any disclosure made under Rule 26(a): the initial, expert, and pretrial disclosures covered earlier in this chapter. The second is the written responses a party gives when an opponent asks, meaning answers to interrogatories, responses to requests for production, and responses to requests for admission, which are written demands that a party admit a stated fact.⁵ The two belong together because an incomplete interrogatory answer misleads an opponent exactly as a faulty disclosure does, and the opponent plans depositions and motions around both.

The duty attaches only to something the party actually made, and it reaches only as far as the original disclosure or response had to reach. That second limit drives a commonly tested scenario. In a bar-exam illustration, Bashad’s initial disclosures omitted Patrick, a witness whose testimony would damage Bashad’s case. Bashad broke no rule. Initial disclosures reach only information the disclosing party may use to support its claims or defenses, a narrower category than the general discovery standard of relevance,⁶ and Bashad would not call a witness who hurts him. The list was complete as the rule defines completeness, so nothing needed correcting. Unless a party has faced discretionary discovery demands, it must supplement only the disclosures it was required to make under Rule 26(a).⁷

Discovery demands move that boundary. Discovery reaches relevant information generally, so an interrogatory asking for every witness to the event would reach Patrick, and an answer that left him out would be incomplete in a material respect.⁸ The correction duty would then apply to the answer, although it never applied to the disclosure.

Rule 26(e)(1)(A) supplies the trigger. The party must act in a timely manner if it learns that in some material respect the disclosure or response is incomplete or incorrect, and if the additional or corrective information has not otherwise been made known to the other parties during the discovery process or in writing.⁹ Three phrases carry the content. The text sets no number of days, so timeliness runs from the moment the party learns of the gap, and a party that holds a new witness’s name until the eve of trial has not acted in a timely manner. The word material filters out trivial change; if every corrected digit in a telephone number demanded a formal paper, parties would bury the changes that matter to the opponent’s preparation. The last condition asks whether the opponent already has the information. The point of the duty is to put information in the opponent’s hands, so a formal supplement adds nothing when the information has arrived through discovery, as in deposition testimony, or in writing, as in a letter from counsel.

One state court, construing its own rule 26, reads those two conditions against a loose demand for updating. The rule, it said, does not require a “wholesale update” to every discovery response. Parties must supplement only if they discover that their initial responses were incomplete or incorrect in some important way and that the other party did not already know the corrective information.¹⁰ That opinion applies a state rule and binds no federal court, but its reasoning carries over to the federal text. Calling a disclosure stale does not trigger the duty. The useful questions are what specific gap exists and whether the opponent already has the information.

The rule also offers a second, independent route: a party must supplement or correct its disclosure or response as ordered by the court.¹¹ The material-gap and not-otherwise-known conditions belong to the preceding clause, so a party under an order supplements on the schedule the judge sets. A judge managing a case knows when updates would help and can fix dates instead of leaving each party to decide what counts as timely. In a silica-exposure case, for example, a court order gave the plaintiffs two weeks to supplement their fact sheets with the types of products used and any identifying product information, and two weeks to add the names, dates, and locations of the work sites where they alleged exposure. Once a work site was identified, the defendants had 80 days to produce sales records for it.¹² Those fact sheets were court-created forms and not Rule 26(a) disclosures, so the order shows how a judge sets update deadlines without construing the rule’s order clause.

Exam Analysis Steps

The duty depends on what the party originally gave, what it has since learned, and what the opponent already has, so work through each disclosure or response in order:

Identify what the party originally gave: a Rule 26(a) disclosure, or a response to an interrogatory, request for production, or request for admission.
Ask whether the new information falls within what that disclosure or response had to contain. Initial disclosures reach only what the party may use; discovery responses reach whatever the request asked for.
Ask whether the party has learned that the disclosure or response is incomplete or incorrect in some material respect, setting aside trivial changes.
Ask whether the corrective information has already been made known to the other parties during the discovery process or in writing. If it has, no formal supplement is required.
Check whether a court order sets a separate duty or date for supplementation, and follow it if one does.
If the duty applies, supplement in a timely manner, measured from the time the party learned of the gap.

Two errors recur on exams. The first treats a witness the party never had to list as a gap, so that a party who learns the opponent has found an adverse witness is said to owe a supplement or to face sanctions, when the original list was complete. The second treats every change as a trigger and overlooks that the gap must be material and that information the opponent already has through discovery or in writing needs no formal paper.

Supplementing Expert Disclosures

Rule 26(e)(2) supplies a supplementation rule written for one group of experts, those who must provide written reports. For an expert whose report must be disclosed under Rule 26(a)(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, and any additions or changes must be disclosed by the time the party’s pretrial disclosures under Rule 26(a)(3) are due.¹⁴ The general duty from the previous subsection turns on a material gap and on what the opponent already has. This provision adds two features for the report expert: it names the places where that expert’s information lives, and it sets a fixed outer date for the update.

The general duty reaches experts through a cross-reference in the expert-disclosure rule. Rule 26(a)(2)(E) directs that the parties must supplement their expert disclosures when required under Rule 26(e).¹⁵ That sentence covers each kind of expert disclosure taught earlier: the identity of any testifying expert, the written report of a retained expert, and the summary disclosure for an expert who need not report. One court opinion summarizes how the provisions interlock. Rule 26(a)(2)(B) requires a report containing “a complete statement of all opinions the witness will express and the basis and reasons for them,” Rule 26(a)(2)(D) puts timing under the court’s order, and Rule 26(e) requires supplementation when the party learns that “in some material respect the disclosure or response is incomplete or incorrect.”¹⁶ Rule 26(e)(2) then narrows to the report expert, which is why the deposition clause and the pretrial-disclosure date attach to that witness and not to a treating physician or other expert who gives only a summary disclosure.

The two sources the rule names, the report and the deposition, mark the places where an expert’s position actually changes. The report is the expert’s complete written statement of opinions, and the deposition is where the opponent tests it. An expert pressed on a mistaken assumption may correct a figure, withdraw a conclusion, or add a ground for one. If the duty covered only the report, the opponent’s picture of the testimony would stay frozen at the written version while the expert’s sworn account moved. Covering deposition testimony keeps the disclosed picture current.

The fixed date does a different job. Without a firm outer limit, the final version of an expert’s testimony could first appear at trial. The drafters required expert disclosure “sufficiently in advance of trial” to give the opposing party “a reasonable opportunity to prepare for effective cross examination and perhaps arrange for expert testimony from [its own] witnesses.”¹⁷ Tying the deadline to the Rule 26(a)(3) date delivers the settled expert picture together with the witness lists, deposition designations, and exhibit lists, while the opponent still has time to prepare.

Two clocks fix the date. Expert disclosures are made at the times and in the sequence the court orders,¹⁸ and the pretrial disclosures come due at least thirty days before trial, as the earlier section on the thirty-day deadline explained. A report expert’s update window therefore runs from the report, through the deposition, to the pretrial date. Because the rule measures to the time the pretrial disclosures are due, the calendar fixes the deadline, and it does not move because a party serves its pretrial lists early or late. When the court sets a different due date for the pretrial disclosures, the supplementation date moves with it.

A different stem exploits the word supplement. The instinct that loses points treats a supplemental report as something a party may serve any time before the expert takes the stand, on the theory that the duty to update never ends.

Lateness carries a cost. A party that fails to provide information or identify a witness as Rule 26(a) or (e) requires may not use that information or witness at trial unless the failure was substantially justified or is harmless, and the opinion describes that exclusion as a self-executing sanction.¹⁹ The next subsection teaches how that exception works, so the point here is only that the deadline has teeth.

The rule also has limits. Rule 26(e)(2) speaks only to an expert whose report must be disclosed, so a retained expert who must report carries the deposition-and-pretrial-date duty. A treating physician who gives only a subject-matter and summary disclosure falls under the general duty that Rule 26(a)(2)(E) imports, with its material-gap trigger and its standard of timeliness. A student who applies the pretrial-disclosure date to every testifying expert has read the clause too broadly, and one who believes a report expert’s duty ends when the report is first served has read it too narrowly.

Consequences of Nondisclosure

Every disclosure duty in this chapter carries a price for ignoring it, and Rule 26(g) separately provides for sanctions for violations of discovery or disclosure.²¹ The sanction that governs evidence is stated in Rule 37(c)(1). A party that fails to provide information or identify a witness as Rule 26(a) or (e) requires “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.”²² The sentence names both ways of falling short. Rule 26(a) supplies the initial, expert, and pretrial disclosures, and Rule 26(e) supplies the continuing duty to supplement or correct. A party can lose evidence by never disclosing it, or by learning that a disclosure has become materially incomplete and saying nothing. The bar also reaches past trial to motions and hearings, so an undisclosed witness cannot supply the affidavit behind a summary-judgment motion any more than testimony at trial.

The preclusion is self-executing, which means it takes effect without the opponent first filing a motion. The opinion describes exclusion as the drafters’ “automatic sanction,” meant to give “a strong inducement for disclosure of material that the disclosing party would expect to use as evidence, whether at trial, at a hearing, or on a motion.”²³ A disclosure rule that cost nothing to violate would be optional, because a party could hold back a witness or exhibit it fully intended to use and unveil it at trial, when the opponent has no chance to investigate. Exclusion removes the payoff that withholding would otherwise bring. The opponent also does not have to win an order compelling disclosure before the bar applies, because the failure itself triggers it.

The rule carries two exceptions: a failure that was substantially justified, and one that is harmless.²⁴ The opinion quotes three illustrations of omissions that fit those exceptions: the inadvertent omission from an initial disclosure of the name of a potential witness known to all parties; the failure to list as a trial witness a person already listed by another party; and a pro se litigant’s lack of knowledge of the disclosure requirement. The last illustration carries a limit, because exclusion would be proper once the court or another party had called the requirement to that litigant’s attention.²⁵ In each illustration the opponent lost nothing the disclosure was meant to provide, since the opponent already knew of the witness or the litigant did not yet know of the duty. The pro se limit shows that the exception does not shield a party who has been told what the rules require and ignores it.

An exam stem on this rule usually describes a party trying to use a witness it never named, and the question is which side of the line the omission falls on.

Hypothetical Illustration

A homeowner sues a contractor after a deck collapses. The contractor’s initial disclosures name two crew members. The contractor has always known that its former site foreman supervised the pour and would support its defense, yet it never listed the foreman and never supplemented its disclosures. The homeowner first hears of the foreman when the contractor calls the foreman to the stand at trial. The foreman is a witness the contractor may use to support its defense, so the initial-disclosure duty reached him. Nothing justifies the omission, because the contractor knew of the witness from the outset, and the omission is not harmless, because the homeowner never had the chance to investigate the foreman. The contractor is not allowed to use the foreman, and the homeowner did not have to file any motion to obtain that result.

The illustration of a person already listed by another party marks the other pole. Had the homeowner’s own initial disclosures named the foreman, the contractor’s failure to list him would have hidden nothing from the homeowner, which is the situation the exception for harmless failures covers.²⁶

The preclusion applies only to information that Rule 26(a) or (e) actually required the party to provide. Bashad’s decision to leave Patrick, the witness whose account hurt him, off his initial disclosures raises no Rule 37(c)(1) question, because the initial-disclosure duty never required him to list a witness he would not use.²⁷ An exam answer should therefore ask whether a disclosure duty existed before it asks about exclusion.

Exam Analysis Steps

The consequence depends on what the rules required, whether the party provided it, and whether an exception applies, so work through the evidence the party wants to use in order:

Ask whether Rule 26(a), or the duty to supplement under Rule 26(e), required the party to provide the information or identify the witness. If neither did, Rule 37(c)(1) is not triggered.
Ask whether the party in fact provided it, either in the original disclosure or in a timely supplement.
If it did not, conclude that the party is not allowed to use the information or witness on a motion, at a hearing, or at trial, and recognize that the opponent needs no motion for the bar to apply.
Ask whether the failure was substantially justified or is harmless, as with the inadvertent omission of a witness known to all parties. If it was, the preclusion does not apply.