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American Bar Association

Trial Evidence Committee

2010 Expert Witness Rule Amendments

By Gregory P. Joseph – April 28, 2011

Effective December 1, 2010, Federal Rule of Civil Procedure 26(a)(2) and (b)(4) are substantially amended. These amendments govern the disclosure of expert opinion, and they entail three principal practice changes.

Communications Between Counsel and Retained Experts
The 2010 amendments would close the door to almost all discovery of communications between counsel and retained experts. This reverses the result under the 1993 amendments to Rule 26(a)(2)(B), which were construed as allowing discovery of all communications between counsel and expert relating to the subject matter of the litigation, for two reasons. First, the 1993 version of Rule 26(a)(2)(B) mandated that the retained expert’s report contain all of “the data or other information considered by the witness in forming” his or her opinion. “Other information” was interpreted to include everything communicated by counsel to expert. See, e.g., Reg’l Airport Auth. v. LFG, LLC, 460 F.3d 697, 716 (6th Cir. 2006).

Second, the 1993 Advisory Committee Note observed that “[g]iven the obligation of disclosure, litigants should no longer be able to argue the materials furnished to their experts to be used in forming their opinions are protected from disclosure when such persons are testifying or being deposed.” Work product protection, to the extent it previously existed, vanished.

The 2010 amendments reverse this result. First, Rule 26(a)(2)(B)(ii) is amended to eliminate the phrase “data or other information.” It now reads, “the facts or data considered by the witness in forming them [the opinions].” The accompanying committee note explains that this amendment “is intended to alter the outcome in cases that have relied on the 1993 formulation in requiring disclosure of all attorney-expert communications and draft reports.” Because this is an amendment to the report requirement, by definition, Rule 26(a)(2)(B)(ii) applies only to counsel’s communications with experts who must file a Rule 26(a)(2)(B) report.

Second, Rule 26(b)(4)(C) is amended to confer work product protection (which is set forth in Rule 26(b)(3)) on most communications between attorneys and retained experts.

Retained and Unretained Experts
Note that Rule 26(b)(4)(C)’s protection for communications between counsel and expert (like the amendment to Rule 26(a)(2)(B)(ii)) applies only to communications with experts from whom Rule 26(a)(2)(B) reports are required—that is, retained experts or party employees who regularly provide expert testimony on behalf of their employer. Amended Rule 26(b)(4)(C) does not protect communications between lawyers and witnesses who provide expert testimony but are not required to furnish a report (non-reporting experts) because they were not “retained or specially employed to provide expert testimony” or their duties as party employees do not “regularly involve giving expert testimony.”

The only unprotected communications between attorneys and reporting experts are those relating to compensation, facts or data provided by counsel and considered by the expert, and assumptions provided by counsel and relied on by the expert.

Compensation. The committee note clarifies that “compensation” includes potential additional work for the expert, as well as compensation for work done by assistants, associates, and affiliated organizations. Presumably, all other financial incentives are freely discoverable, as “[t]he objective is to permit full inquiry into such potential sources of bias.”

“Considered” versus “Relied On.” There is a world of difference between facts or data “considered” (Rule 26(a)(2)(B)(i)) and assumptions “relied on” (Rule 26(a)(2)(B)(ii)), as those quoted words have been interpreted in the jurisprudence of Rule 26(a)(2). “Considered” is the word used in the 1993 version of Rule 26(a)(2)(B)(ii), and, together with the now-stricken “other information,” it was read as requiring disclosure of all communications between attorney and expert “related to the subject matter of the litigation.” See Karn v. Ingersoll Rand, 168 F.R.D. 633, 639 (N.D. Ind. 1996) (noting that the Advisory Committee in 1993 substituted “considered” for the more restrictive “relied upon” in an earlier draft of rule 26(a)(2)(B)).

Under the 2010 amendment, “considered” is confined to “facts or data” provided by counsel but does not apply to counsel-supplied “assumptions” (those must be “relied on”). Therefore, all facts or data communicated by counsel relating to the subject matter of the litigation must be “identif[ied].” The committee note stresses that “the refocus of disclosure on ‘facts or data’ is meant to limit disclosure to material of a factual nature by excluding theories or mental impressions of counsel.” Some of us argued years ago that “data or other information” could, and should, be read to the same effect because “‘[d]ata’ and ‘information’ connote subjects that are factual in nature, not ephemera like ‘mental impressions, conclusions, opinions or legal theories’ of the sort protected by Rule 26(b)(3).” Joseph, Emerging Expert Issues under the 1993 Disclosure Amendments to the Federal Rules of Civil Procedure, 164 F.R.D. 97, 104 (1996). While some decisions agreed with that approach, the overwhelming majority rule was to the contrary.

The committee note also emphasizes that “the intention is that ‘facts or data’ be interpreted broadly to require disclosure of any material considered by the expert, from whatever source, that contains factual ingredients,” and the facts or data need only be identified—“further communications about the potential relevance of the facts or data are protected.”

In contrast, assumptions furnished by counsel are discoverable only if the expert actually relied on them in forming his or her opinion.

“Regardless of the Form of the Communications”
One of the textual problems with the former Rule 26(b)(3) is that it affords work product protection only to “documents and tangible things.” Work product takes many forms that are non-documentary and intangible, including discussions. For these, litigants must rely on common law protection, derived from Hickman v. Taylor, 329 U.S. 495, 510–11 (1947). See 6 Moore’s Federal Practice § 26.70[2][c] (3d ed. 2010). Rule 26(b)(4)(C) explicitly covers the waterfront, extending to all forms of communication.

“A Party’s Attorney”
Parties often have many attorneys, including in-house counsel, outside general counsel, and counsel in other cases dealing with the same or similar subject matters. The committee note to Rule 26(b)(4)(C) stresses that the work product protection it recognizes “should be applied in a realistic manner,” generally extending to these lawyers, each of whom is “the party’s attorney,” albeit not necessarily before the court, and observes that “[o]ther situations may also justify a pragmatic application of the ‘party’s attorney’ concept.”

The Discoverability of Draft Expert Reports
The previously discussed change to Rule 26(a)(2)(B)(ii) (“the facts or data considered by the witness”) is one of the two amendments proposed to protect draft expert reports, as reflected in the excerpt from the committee note quoted above. The second, direct approach is new Rule 26(b)(4)(B), which protects drafts of any report required under Rule 26(a)(2), regardless of the form in which the draft is recorded.

Non-Reporting Experts
Under Rule 26(b)(4)(B), work product protection extends to written or otherwise “recorded” drafts of the new Rule 26(a)(2)(C) disclosures (discussed below), which summarize the testimony of experts who are not obliged to file a 26(a)(2)(B) report. Query whether audio recording one’s conversations with a non-reporting expert concerning his or her opinion suffices to place the conversations within the work product protection afforded by Rule 26(b)(4)(B), the issue being whether that conversation constitutes a “draft.”

Impact on Discovery and Cross-Examination
The proposed committee note discusses the breadth of work product protection afforded by Rules 26(b)(4)(B) and (C): (1) The protection extends to all forms of discovery, including depositions; (2) there is no other limit on exploring the foundation for expert opinion; and (3) one must show substantial need to obtain additional discovery.

Privilege Implications
Rules 26(b)(4)(B) and (C) address only work product protection, but they have potential attorney-client privilege repercussions. One effect of the 1993 amendments to Rule 26(a)(2)(B) was to make waiver an unavoidable cost of putting an expert forward to testify. Because communications between counsel and expert, and draft expert reports, were subject to disclosure and discovery, no plausible expectation of confidentiality could be asserted. Therefore, no viable claim of attorney-client privilege could be asserted with respect to those communications.

The amendments to Rules 26(b)(4)(B) and (C), however, reverse the expectation. It is true that, under Rules 26(b)(3)(A) and (B), an opposing party may obtain disclosure of work product on a showing of “substantial need” and an inability, “without undue hardship, [to] obtain their substantial equivalent by other means.” The committee note that accompanies the amendments contemplates that “[i]t will be rare for a party to be able to make such a showing given the broad disclosure and discovery otherwise allowed regarding the expert’s testimony.” Certain communications between attorney and expert may again be subject to a reasonable expectation of privacy and fall within the umbra of attorney-client privilege.

Disclosure Requirements for Non-Reporting Experts
Prior to the 2010 amendments, there were no mandatory disclosure requirements for non-reporting experts. The report requirement of Rule 26(a)(2)(B) was confined to 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.” If anyone else was to provide expert testimony in a case—a treating physician, an employee whose duties did not regularly involve giving expert testimony, a third-party witness—no report was required. Instead, under Rule 26(a)(2)(A), the proponent of the testimony was simply required to “disclose to the other parties the identity of any witness it may use at trial to present evidence under Federal Rule of Evidence 702, 703, or 705.” The absence of any required disclosures for non-reporting experts lent itself to the prospect of trial by ambush and to district judges occasionally imposing disclosure requirements on an ad hoc basis. The 2010 Rule 26(a)(2)(C) mandates counsel-prepared disclosures for non-reporting experts. This requirement is similar in substance to the pre-1993 version of Rule 26(b)(4)(A), which permitted expert discovery primarily by means of interrogatories.

Keywords: litigation, trial evidence, expert witnesses, Federal Rules of Civil Procedure

Gregory P. Joseph of Gregory P. Joseph Law Offices, LLC, New York, New York, is president of the American College of Trial Lawyers and former chair of the Section of Litigation.

“2010 Expert Witness Rule Amendments,” by Gregory P. Joseph, 2011, Proof 19:2, p. 3. Copyright 2011 © by the American Bar Association. Reprinted with permission.


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  2. Scheuplein v. City of W. Covina, 2009 Cal. App. Unpub. LEXIS 7805, at*26–27 (Cal. Ct. App. Sept. 29, 2009).
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  16. Fed. R. Evid. 802(d)(2)(E).
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  19. United States v. Tellier, 83 F. 3d 578, 580 (2d Cir. 1996).
  20. Fed. R. Evid. 801(d)(2)(B).
  21. Safavian, 435 F. Supp. 2d at 43–44.
  22. United States v. Joe, 8 F.3d 1488, 1493 (10th Cir. 1993).
  23. Brill v. Lante Corp., 119 F.3d 1266, 1271 (7th Cir. 1997).
  24. Safavian, 435 F. Supp. 2d at 36.
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  28. Pursuit Partners, LLC v. UBS AG, 2009 Conn. Super. LEXIS 2313 (Super. Ct. Conn. Sept. 8, 2009).

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