Bench & Bar of Minnesota is the official publication of the Minnesota State Bar Association.

How to Be an Expert on Expert Discovery

Disclosure obligations and discovery limitations under Minnesota Rule of Civil Procedure 26

A set of 2013 amendments to Minnesota Rule of Civil Procedure 26 has changed the playing field with respect to disclosure and discovery requirements regarding expert witnesses. The modified rule contains traps for the unwary attorney—particularly when it comes to those witnesses with personal knowledge of the facts of the case as well as the qualifications to render expert opinions.

In 2013, the Minnesota Supreme Court adopted extensive amendments to Minnesota Rule of Civil Procedure 26, incorporating expert discovery provisions that conform largely (though not entirely) to Federal Rule 26. (New amendments to Federal Rule 26 became effective December 1, 2015, but the expert discovery provisions discussed in this article remain unchanged.) The 2013 amendments raise two significant issues for Minnesota litigators.

First, Minnesota Rule 26 now requires that parties serve not only written reports from retained testifying experts—a familiar obligation in federal practice—but also disclosures regarding the expected testimony of any other witness who may provide expert opinion testimony. The latter requirement, which generally applies to fact witnesses with relevant expertise (such as treating physicians or certain party employees), only appeared in the Federal Rules in 2010, and many practitioners remain unfamiliar with it. Federal case law shows this disclosure obligation can be a trap for the unwary.

The second significant issue the amendments raise concerns discoverability of draft expert reports and communications between retained testifying experts and counsel. Federal Rule 26(b)(4) expressly protects such materials from discovery. Yet while the 2013 amendments to Minnesota Rule 26 adopted the federal rule’s expert disclosure obligations, they did not incorporate the federal rule’s express discovery protections. This raises the question whether draft expert disclosures and communications between counsel and retained experts containing work product are discoverable in Minnesota courts. To date, no Minnesota court has addressed that question under the new Rule 26, but preexisting provisions in the rule, read in the context of the divergent historical evolution of the federal and Minnesota rules, indicate that such materials should not be discoverable in Minnesota courts. Put simply, Minnesota Rule 26 protected such materials from discovery before the 2013 amendments, and the adoption of the federal disclosure requirements should not be read to abrogate that protection.

Minnesota’s New Expert Disclosure Requirements

Minnesota’s Rule 26 now conforms to its federal counterpart with regard to disclosure of experts. The obligation to serve written reports for retained testifying experts comes as no surprise to Minnesota litigators, as it has been part of federal practice since 1993. The new Minnesota Rule 26 also incorporates a lesser known obligation, however—the requirement to disclose a summary of the expected testimony of any witness who may offer expert testimony at trial under Rules of Evidence 702, 703, or 705. That obligation was added to the Federal Rules in 2010, and it remains unfamiliar to many practitioners.

Minnesota Rule 26.01(b) now divides expert witnesses into two distinct categories, and imposes different disclosure requirements on each.

Expert witnesses who must provide a written report: This category includes any witness “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.”1 This encompasses both the classic retained outside expert and employees who regularly testify as part of their jobs.2 These witnesses must provide the complete report with which most litigators are familiar, disclosing a “complete statement of all opinions the witness will express and the basis and reasons for them,” the “facts or data considered by the witness in forming them,” “any exhibits that will be used to summarize or support them,” the “witness’s qualifications, including a list of all publications authored in the previous 10 years,” 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 “a statement of the compensation to be paid for the study and testimony in the case.”3

There is a wealth of case law interpreting these provisions of Rule 26. This article focuses, however, on less-developed principles applicable to the second category of experts, those who are not required to provide a written report.

Expert witnesses who do not provide a written report: This second category of experts is a residual catch-all—including any expert witness who is “not required to provide a written report.”4 Before turning to the specific disclosure requirements for this category, it is important first to grasp the breadth of subsection (b)(3). Rule 26.01 requires written disclosures regarding “any witness” the party “may use at trial to present evidence under Rules of Evidence 702, 703, or 705.”5 Subsection (b)(3) applies to any witness not required to provide a written report under subsection (b)(2). It follows that a party must, at minimum, provide the written disclosures required under subsection (b)(3) regarding any witness who may offer expert testimony.
Generally these will be witnesses who have some personal knowledge of the facts of the case, but also have the qualifications to render expert opinions on relevant issues—what some courts have called “percipient or hybrid expert[s].”6 A simpler term may be “fact witnesses with expertise.” Classic examples are treating physicians and party employees with technical expertise, such as engineers.7

The key to distinguishing between “retained” experts who must provide a report and those subject to the lesser disclosure requirements of subsection (b)(3) is whether the “witness’s opinion was developed either for purposes of litigation or as part of the witness’s duties as the party’s employee.”8 If a party asks its witness to develop an opinion for purposes of litigation, the witness is a retained expert subject to the reporting requirements of Rule 26.01(b)(2).9 In contrast, if the witness is “a percipient witness who happens to be an expert,” he need not provide a full report under subsection (b)(2), but he is subject to the lesser disclosure requirements of subsection (b)(3).10

Disclosures Required Under Rule 26.01(b)(3)

The disclosure requirements of Rule 26.01(b)(3) are not onerous, but they go well beyond simply identifying the witness. Disclosures under this subsection must state “(A) the subject matter on which the witness is expected to present evidence under Minnesota Rule of Evidence 702, 703, or 705; and (B) a summary of the facts and opinions to which the witness is expected to testify.” The rule does not define the level of detail required, and the authors are not aware of any Minnesota case law that explores the issue. Case law and commentary on the analogous federal rule provides some helpful guidance, however.11

The Federal Advisory Committee’s comments on Federal Rule 26(a)(2)(C) state that the disclosure required for non-retained experts is “considerably less extensive than the report required” of retained experts.12 The committee cautions that “[c]ourts must take care against requiring undue detail, keeping in mind that these witnesses have not been specially retained and may not be as responsive to counsel as those who have.”13

These comments indicate the disclosures should not be burdensome, but case law shows that a reasonable level of detail is still required. Federal courts have focused on the purpose of the disclosure requirement, which several courts have agreed is “to allow the party in receipt of the disclosure to be able to read the disclosure and immediately be able to identify whether it needs a responsive witness and the information that such responsive witness would need to address.”14 Thus, the “summary” disclosures must explain both the particular opinions the witness is expected to offer and the factual bases for them, in sufficient detail to allow other parties to assess the opinions and determine whether responsive evidence is required.15

As the plain language of the rule indicates—and case law confirms—merely disclosing the subject of a witness’s expected testimony is not enough to satisfy Rule 26(a)(2)(C).16 Likewise, a party cannot merely point to documents from which the substance of a non-retained expert’s testimony can be gleaned. In medical litigation, for example, parties sometimes try to disclose the opinions of treating physicians by simply referring to medical records. Courts have consistently rejected these efforts as inadequate.17 As one court explained, “Rule 26(a)(2)(C) doesn’t allow parties to sidestep their obligations… by making a broad, generic reference to previously disclosed discovery documents.”18

Taken together, these authorities indicate that the disclosures required under Minnesota Rule 26.01(b)(3) need not be onerous or exhaustive, but they must be meaningful. Parties cannot satisfy the rule with boilerplate disclosures; they cannot merely identify witnesses and point to documents. Instead, a party must describe the specific opinions a fact witness with expertise may offer and the factual grounds for them. Failure to do so risks exclusion of the undisclosed testimony.19

Discoverability of Draft Disclosures and Communications with Experts

The 2013 amendments to Minnesota’s Rule 26 raise a significant question about discovery of expert witness materials, because the amendments incorporated the federal disclosure obligations but did not adopt the express work-product protections Federal Rule 26 affords draft expert disclosures and certain communications between counsel and retained experts. The omission of these express protections could be interpreted as revealing an intent to render draft disclosures and communications subject to discovery. The authors are not aware of any Minnesota case law addressing this question. But the language of Minnesota Rule 26.02(e), pre-2013 case law, and the evolution of Federal Rule 26 (upon which the current Minnesota rule is modeled), all support the conclusion that Minnesota’s Rule 26 limits discovery of expert materials in a way that is practically similar to the federal rule, albeit by a different mechanism.

The 2010 amendments to Federal Rule 26 extended work-product protection to draft expert disclosures and certain communications between retained experts and counsel. Specifically, Federal Rule 26(b)(4)(B) provides that Rules 26(b)(3)(A) and (B), which codify the work-product doctrine, “protect drafts of any report or disclosures required under Rule 26(a)(2), regardless of the form in which the draft is recorded.”20 Rule 26(b)(4)(C) extends the same protection to “communications between the party’s attorney and any witness required to provide a report under Rule 26(a)(2)(B),” i.e., retained experts.21 The protection of communications does not extend to certain enumerated topics—communications concerning compensation, identifying facts or data provided to the expert, or identifying assumptions provided by counsel and relied upon in forming the expert’s opinions.22

These amendments were intended to preclude wide-ranging discovery of theories, strategies, and mental impressions of counsel through inquiry into drafts and communications with experts and to refocus expert discovery on what parties truly need to effectively oppose and cross-examine experts: factual information underlying the experts’ opinions. As the Federal Rules Advisory Committee explained:

The Committee has been told repeatedly that routine discovery into attorney-expert communications and draft reports has had undesirable effects. Costs have risen. Attorneys may employ two sets of experts—one for purposes of consultation and another to testify at trial—because disclosure of their collaborative interactions with expert consultants would reveal their most sensitive and confidential case analyses. At the same time, attorneys often feel compelled to adopt a guarded attitude toward their interaction with testifying experts that impedes effective communication, and experts adopt strategies that protect against discovery, but also interfere with their work.23

The amendments to Federal Rule 26(b)(4) were thus driven by a clear policy of fostering open communication between counsel and experts and avoiding wasteful discovery practices.

Minnesota Rule 26.02(e), like its federal counterpart, is entitled “Trial Preparation: Experts.” Unlike Federal Rule 26(b)(4), it does not contain express work-product protections for draft expert disclosures and expert communications. But Minnesota Rule 26 has long included specific limitations on methods of discovery
that may be directed toward expert witnesses. Rule 26.02(e) provides, in relevant part:

Discovery of facts known and opinions held by experts, otherwise discoverable pursuant to Rule 26.02(b) and acquired or developed in anticipation of litigation or for trial, may be obtained only as follows:

(1)(A) A party may through interrogatories require any other party to identify each person whom the other party expects to call as an expert witness at trial, to state the subject matter on which the expert is expected to testify, and to state the substance of the facts and opinions to which the expert is expected to testify and a summary of the grounds for each opinion. (B) Upon motion the court may order further discovery by other means….24

As its first sentence indicates, Rule 26.02(e) establishes the exclusive methods for discovery of “facts known and opinions held by experts” that have been “acquired or developed in anticipation of litigation or for trial.” Absent a court order, it permits only one method of discovery directed to retained testifying experts—interrogatories regarding: (1) the identity of the witness; (2) the subject of her testimony; (3) the substance of the facts and opinions to which the expert will testify; and (4) a summary of the grounds for each opinion.25 Thus, before the addition of the expert disclosure requirements in 2013, interrogatories were the only permissible method of discovery directed toward retained testifying experts in Minnesota courts, absent a court order.26

The Minnesota Supreme Court confirmed this rule in Dennie v. Metropolitan Medical Center.27 There, the defendant sought production of a report and letter in which the plaintiff’s experts explained their opinions to plaintiff’s counsel. The plaintiff refused to produce the documents, asserting a work-product objection. On appeal, the Minnesota Supreme Court clarified that, “[t]echnically speaking,” these documents were “not work product but [their] discoverability [was] governed by” Rule 26.02(e).28 Under that rule, the court explained, “the contents of [the documents] are discoverable only by interrogatory and, if necessary, deposition, but not by production of documents.”29

Thus, in Minnesota courts, the rule has long been that draft expert reports, communications between retained experts and counsel, and other documents revealing “facts known and opinions held by experts… and acquired or developed in anticipation of litigation or for trial” are not subject to discovery, absent permission of the court.30 A party can serve interrogatories regarding experts’ opinions and the bases for them, but that is the limit of discovery permitted as a matter of course.

Nothing in the 2013 amendments to Minnesota Rule 26 abrogated the limitations imposed by Rule 26.02(e). The plain language of the disclosure obligations indicates no intention to permit broader discovery of expert materials. And while the fact that Minnesota did not adopt the federal rule’s express protections for such materials could be interpreted to imply such an intention, the specific language of the new disclosure requirements in Rule 26.01(b)—read in light of the history of the federal rule from which the language was taken—indicates otherwise.

Before 2010, Federal Rule 26(a)(2)(B)(ii) required an expert report to disclose the “data or other information considered by the witness in forming” his or her opinions.31 The Advisory Committee notes explaining the adoption of this language in 1993 said that “[g]iven this obligation of disclosure, litigants should no longer be able to argue that materials furnished to their experts to be used in forming their opinions—whether or not ultimately relied upon by the expert—are privileged or otherwise protected from disclosure when such persons are testifying or being deposed.”32 It was this specific commentary—as well as the rule’s reference to disclosure of “other information”—that led the majority of federal courts to hold that draft expert reports and communications with experts were discoverable, even if they contained attorney work-product. As the 9th Circuit recently explained:

The requirement [in the pre-2010 Rule 26(a)(2)(B)(ii)] to disclose “data or other information” considered by the expert in forming the opinions coupled with the implication in Rule 26(b)(3) that the work product protection was “subject to” provisions requiring expert depositions led many courts to conclude that “any material given by an attorney to an expert was discoverable,” including opinion work product. The Sixth Circuit’s decision in Regional Airport Authority of Louisville v. LFG, LLC, 460 F.3d 697 (6th Cir. 2006), is illustrative. There, the Sixth Circuit adopted the then-majority view “in holding that Rule 26 creates a bright-line rule mandating disclosure of all documents, including attorney opinion work product, given to testifying experts.” Id. at 717. The court read the disclosure obligation as “requiring disclosure of more than facts” because the drafters had included the phrase “or other information.” Id. at 716. Since there was no “qualifier as to the extent of the information,” the court concluded that “none was intended” and the rule “required disclosure of all information provided to testifying experts.”33

As detailed above, the Federal Rules Advisory Committee was dissatisfied with the discovery practices that developed under this interpretation of the expert disclosure provisions. Permitting discovery of draft reports and attorney work-product hampered attorneys’ ability to work freely and efficiently with their expert witnesses, and some attorneys resorted to elaborate and expensive practices to avoid discovery, like conducting live drafting sessions with experts rather than exchanging written comments on draft reports. The 2010 amendments to Federal Rule 26 were meant to change these practices; indeed, the Advisory Committee stated that they were specifically intended “to alter the outcome in cases” like Regional Airport Authority by changing the language of Rule 26(a)(2)(B)(ii) to require “that disclosure include all ‘facts or data considered by the witness in forming’ the opinions to be offered, rather than the ‘data or other information’ disclosure prescribed in 1993.”34 The “refocus of disclosure on ‘facts or data’ [was] meant to limit disclosure to material of a factual nature by excluding theories or mental impressions of counsel.”35

The Advisory Committee regarded the change in the language of the disclosure provision itself, Rule 26(a)(2)(B), as sufficient to countermand the case law that had permitted discovery of draft reports and attorney work product. The express protections for these materials that were concomitantly added to Rule 26(b)(4) were simply meant to “make this change explicit.”36 This illuminates the proper interpretation of the new Minnesota rule, because Minnesota’s 2013 amendments to Rule 26 adopted the language of the post-2010 federal disclosure rule. Since it is clear that the language of the latter rule was specifically altered to prevent discovery of draft expert reports and attorney work-product, it should be equally clear that Minnesota’s adoption of that language in 2013 was not intended to alter Minnesota’s preexisting limitations on expert discovery.

BILL STOERI is a partner at Dorsey & Whitney LLP and chair of the firm’s Health Litigation Practice Group. Bill’s practice covers litigation in the health care industry and general commercial litigation, including a variety of contract and tort claims, such as licensing agreements, trade secrets, products liability, consumer fraud, class actions, and medical malpractice.

ANDREW BRANTINGHAM is an associate at Dorsey & Whitney LLP. Andrew’s practice includes civil litigation in a range of industries and areas, focusing on health industry litigation, federal Indian law, general commercial litigation, and appeals.


1 Minn. R. Civ. P. 26.01(b)(2).

2 For the sake of simplicity this article refers to all witnesses in this category as “retained experts.”

3 Minn. R. Civ. P. 26.01(b)(2)(A)-(F).

4 Minn. R. Civ. P. 26.01(b)(3).

5 Minn. R. Civ. P. 26.02(b)(1) (emphases added). Rule of Evidence 702 establishes when expert testimony is appropriate and who may offer it. Rules 703 governs permissible bases of expert opinion testimony, and Rule 705 covers disclosure of facts or data underlying the testimony.

6 Burreson v. BASF Corp., No. 2:13-cv-0066 (TLN AC), 2014 WL 4195588, at *4 (E.D. Cal. 8/22/2014).

7 See Fed. R. Civ. P. 26, Advisory Comm. Cmt. (2010 Amendments) (citing “physicians and employees of a party who do not regularly provide expert testimony” as “[f]requent examples” of witnesses in this category); Little Hocking Water Ass’n, Inc. v. E.I. DuPont de Nemours & Co., No. 2:09-CV-1081, 2015 WL 1105840 (S.D. Ohio Mar. 11, 2015) (discussing disclosure of expected testimony of scientists and engineers employed by party).

8 Burreson, 2014 WL 4195588, at *4; see also, e.g., Gomez v. Rivera Rodriguez, 344 F.3d 103, 113 (1st Cir. 2003)
(“[T]he triggering mechanism for application of [the full report obligation] is not the status of the witness, but, rather, the essence of the proffered testimony.”).

9 See Onofre v. Molina, No. 27-CV-13-11066, 2014 WL 2727085, at *2 (Minn. 4th Jud. Dist. Apr. 17, 2014) (“If any of Plaintiff’s treating doctors will offer an opinion not formed during the course of the treatment, Plaintiff must provide a written report pursuant to Minn. R. Civ. P. 26.01(b)(2).”).

10 Gomez, 344 F.3d at 113.

11 See Onofre, 2014 WL 2727085, at *2 (following federal case law because the “Minnesota expert disclosure requirements were modeled after the Federal Rules of Civil Procedure”).

12 Fed. R. Civ. P. 26 Advisory Comm. Cmt. (2010 Amendments).

13 Id.

14 Cooke v. Town of Colorado City, No. CV 10-08105-PCT-JAT, 2013 WL 551508, at *4 (D. Ariz. Feb. 13, 2013); see also Burreson, 2014 WL 4195588, at *3 (“Both the Rule 26(a)(2)(B) written report and the Rule 26(a)(2)(C) disclosure share the goal of increasing efficiency and reducing unfair surprise.”) (quotation marks and citation omitted).

15 The Advisory Committee notes recognize that non-retained witnesses may not be “responsive to counsel,” and indeed, practitioners may occasionally need to disclose a nonparty witness without knowing exactly what the witness might say on the stand. In that circumstance courts should permit less-detailed disclosures; a party can only disclose what it knows.

16 See, e.g., Cooke, 2013 WL 551508, at *4 (rejecting as insufficient a disclosure that “advise[d] the reader that the witness will have opinions in certain areas, but fail[ed] to state what the opinions are, and the factual basis for those opinions”) (emphasis in original); Jennings v. Dow Corning Corp., No. 12-12227, 2013 WL 625591, at *2 (E.D. Mich. Feb. 20, 2013) (“While Plaintiff’s supplemental expert disclosures could be stretched to satisfy the Rule’s requirement to disclose the subject matter the witnesses will testify about, there is nothing to construe as ‘a summary of the facts and opinions to which the witness is expected to testify.’”).

17 See, e.g., Brown, 2011 WL 4498824, at *1 (“The court will not place the burden on Defendants to sift through medical records in an attempt to figure out what each expert may testify to.”); Carillo v. B&J Andrews Enters., LLC, No. 2:11-cv-01450-RCJ-CWH, 2013 WL 394207, at *5-6 (D. Nev. Jan. 29, 2013) (“[P]roduction or disclosure of medical records, standing alone, is not sufficient to satisfy the requirements of Rule 26(a)(2)(C).”).

18 Ibey v. Trinity Universal Ins. Co., No. CV 12-31-M-DWM, 2013 WL 4433796, at *3 (D. Mont. 8/16/2013).

19 See Minn. R. Civ. P. 37.03(a); Cooke, 2013 WL 551508, at *5 (excluding undisclosed testimony of treating physician).

20 Fed. R. Civ. P. 26(b)(4)(B).

21 Fed. R. Civ. P. 26(b)(4)(C).

22 See Fed. R. Civ. P. 26(b)(4)(C)(i)-(iii).

23 Fed. R. Civ. P. 26 Advisory Comm. Cmt. (2010 Amendments).

24 Minn. R. Civ. P. 26.02(e) (emphasis added).

25 As for non-testifying (e.g., consulting) experts, Rule 26.02(b)(2) only permits discovery as provided in Rule 35 (governing medical examinations) or pursuant to court order, upon a showing of “exceptional circumstances.”

26 A notable effect of Rule 26.02(e) is that there is no right to expert depositions as a matter of course in Minnesota courts, whereas Federal Rule 26(b)(4)(A) expressly provides for them.

27 387 N.W.2d 401 (Minn. 1986).

28 Dennie, 387 N.W.2d at 407. At the time of the Dennie decision, the language now contained in Rule 26.02(e)
was numbered as Rule 26.02(4). See 387 N.W.2d at 407.

29 Id.

30 Minn. R. Civ. P. 26.02(e).

31 See, e.g., S. Yuba River Citizens League v. Nat’l Marine Fisheries Serv., 257 F.R.D. 607, 611 (E.D. Cal. 2009).

32 Fed. R. Civ. P. 26 Advisory Comm. Cmt. (1993 Amendments).

33 Republic of Ecuador v. Mackay, 742 F.3d 860, 869 (9th Cir. 2014) (alterations omitted); cf. In re Pioneer Hi-Bred Int’l, Inc., 238 F.3d 1370, 1375 (Fed. Cir. 2001) (“[T]he 1993 amendments to Rule 26 . . . make clear that documents and information disclosed to a testifying expert in connection with his testimony are discoverable by the opposing party.”).

34 Fed. R. Civ. P. 26 Advisory Comm. Cmt. (2010 Amendments) (emphasis added).

35 Id.; see also Mackay, 742 F.3d at 870 (“[M]aterials containing ‘factual ingredients’ are discoverable, while opinion work product is not discoverable.”).

36 Fed. R. Civ. P. 26 Advisory Comm. Cmt. (2010 Amendments).

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