                 FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


REPUBLIC OF ECUADOR; DIEGO               No. 12-15572
GARCIA CARRION, DR., Attorney
General of the Republic of Ecuador,        D.C. No.
                Plaintiffs-Appellees,   1:12-mc-00008-
                                           LJO-GSA
                 v.

DOUGLAS M. MACKAY; CHEVRON
CORPORATION,
           Defendants-Appellants.


     Appeal from the United States District Court
         for the Eastern District of California
     Lawrence J. O’Neill, District Judge, Presiding
2          REPUBLIC OF ECUADOR V. MACKAY

THE REPUBLIC OF ECUADOR; DIEGO              No. 12-15848
GARCIA CARRION, DR., Attorney
General of the Republic of Ecuador,           D.C. No.
               Applicants-Appellees,       3:11-mc-80171-
                                                CRB
                  v.

MICHAEL A. KELSH, DR.; EXPONENT,             OPINION
INC., DBA Delaware Exponent, Inc.,
           Respondents-Appellants,

                 and

CHEVRON CORPORATION,
            Intervenor-Appellant.


      Appeal from the United States District Court
          for the Northern District of California
    Charles R. Breyer, Senior District Judge, Presiding

                Argued and Submitted
      December 4, 2013—San Francisco, California

                  Filed January 31, 2014

    Before: Barry G. Silverman, Consuelo M. Callahan,
           and N. Randy Smith, Circuit Judges.

               Opinion by Judge Callahan
              REPUBLIC OF ECUADOR V. MACKAY                           3

                           SUMMARY*


                             Discovery

    The panel affirmed two district courts’ decisions ordering
the production of documents for use in a foreign proceeding
under 28 U.S.C. § 1782.

    The panel held that the 2010 amendments to Federal Rule
of Civil Procedure 26 did not fundamentally change the scope
of work product protection for expert materials. It therefore
rejected the argument that the district courts erred because
many of the documents at issue were presumptively immune
from discovery under Rule 26(b)(3)’s protection for trial
preparation materials. Arriving at the same result as two
other circuits, the panel held that Rule 26(b)(3) does not
provide presumptive protection for all testifying expert
materials as trial preparation materials.


                            COUNSEL

Theodore J. Boutrous, Jr. (argued), Gibson Dunn & Crutcher,
LLP, Los Angeles, California; Ethan Douglas Dettmer,
Joshua S. Lipshutz, and Enrique Antonio Monagas, Gibson
Dunn & Crutcher, LLP, San Francisco, California, for
Intervenor-Appellant and Respondents-Appellants.




  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
4           REPUBLIC OF ECUADOR V. MACKAY

Gene C. Schaerr (argued) and Eric Bloom, Winston &
Strawn, Washington, D.C.; Richard A. Lapping, Winston &
Strawn, San Francisco, California, for Applicants-Appellees.


                         OPINION

CALLAHAN, Circuit Judge:

    Chevron Corporation and two of its expert witnesses,
Douglas M. Mackay and Michael A. Kelsh (collectively,
“Chevron”), appeal from two district court decisions ordering
the production of documents. The Republic of Ecuador (the
“Republic”) and Diego Garcia Carrion (collectively, the
“Applicants”) sought the discovery for use in a foreign
proceeding under 28 U.S.C. § 1782. Contending that the
2010 amendments to Federal Rule of Civil Procedure 26
fundamentally changed the scope of work product protection
for expert materials, Chevron argues that the district courts
erred because many of the documents at issue were
presumptively immune from discovery under Rule 26(b)(3)’s
protection for trial preparation materials. We find no merit to
Chevron’s arguments, and accordingly, we affirm the district
courts.

                               I

                              A

    The parties are involved in a long-running legal dispute
that has stretched across multiple decades, tribunals, and
continents. This appeal represents one of many skirmishes in
the ongoing conflict, including two nearly identical appeals
that were recently decided by the Tenth and Eleventh
            REPUBLIC OF ECUADOR V. MACKAY                   5

Circuits. Republic of Ecuador v. Hinchee, __ F.3d __, No.
12-16216, 2013 WL 6655490 (11th Cir. Dec. 18, 2013);
Republic of Ecuador v. For Issuance of a Subpoena Under
28 U.S.C. Sec. 1782(a) (Bjorkman), 735 F.3d 1179 (10th Cir.
2013). We briefly review the underlying facts to provide
context for the issue on appeal.

    In 1964, a subsidiary of Texaco, Inc. (“Texaco”) began oil
exploration and drilling in eastern Ecuador. Chevron Corp.
v. Berlinger, 629 F.3d 297, 301 (2d Cir. 2011). Texaco
subsequently began operating a consortium in the area that
conducted drilling activities and operated a pipeline. Id.
Ecuador’s state-owned oil company, Petroecuador, acquired
an interest in the consortium, subsequently becoming the
majority shareholder in 1976, and eventually acquired full
ownership in 1990. Id. Texaco ceased operating the
consortium in 1992. Chevron Corp. v. Naranjo, 667 F.3d
232, 235 (2d Cir. 2012), cert. denied, 133 S. Ct. 423 (2012).

     In 1993, a group of Ecuadorians brought a class action
suit in the Southern District of New York against Texaco
seeking billions of dollars in damages for environmental
pollution and contamination allegedly caused by the
consortium’s activities (the “Aguinda” action). Berlinger,
629 F.3d at 301; see generally Aguinda v. Texaco, Inc.,
303 F.3d 470 (2d Cir. 2002). At Texaco’s urging and over
the plaintiffs’ opposition, the case was dismissed on forum
non conveniens grounds in 2001 with Texaco consenting to
jurisdiction in Ecuador. See Berlinger, 629 F.3d at 301–02 &
n.2.

    In the interim, Texaco entered into a settlement agreement
with the Republic and Petroecuador in 1998, agreeing to
perform remediation projects in exchange for a release from
6           REPUBLIC OF ECUADOR V. MACKAY

liability. Naranjo, 667 F.3d at 235. In 2001, Chevron
purchased Texaco. Id. at 235 n.2. Chevron has since asserted
that the release covered any public claims related to the
environmental harm because, at that time, the Republic
owned the rights to any such claims. For their part, the
Aguinda plaintiffs entered into an agreement where they
waived any claims against the Republic and Petroecuador
(which was allegedly responsible for a significant amount of
the pollution). Chevron v. Donziger, 768 F. Supp. 2d 581,
597–99 & n.18 (S.D.N.Y. 2011), rev’d sub nom. Naranjo,
667 F.3d at 234.

    In 2003, a second group of Ecuadorians, including many
of the Aguinda plaintiffs, brought suit against Chevron in
Lago Agrio, Ecuador (the “Lago Agrio” action). Berlinger,
629 F.3d at 302. Invoking a 1999 environmental law, the
Lago Agrio plaintiffs asserted public claims that Chevron
contends the Republic had previously released. Id. The Lago
Agrio court ordered an independent expert to conduct a global
damages assessment. Donziger, 768 F. Supp. 2d at 603;
Berlinger, 629 F.3d at 302. The court eventually entered a
judgment of over $18 billion against Chevron. The judgment
was recently cut in half but otherwise upheld by Ecuador’s
highest court. Hinchee, 2013 WL 6655490, at *1.

    While the Lago Agrio action was ongoing, the plaintiffs’
attorneys commissioned a documentary which was eventually
released as Crude: The Real Price of Oil. Naranjo, 667 F.3d
at 236. Based on some of the footage, Chevron engaged in a
broad-based – and largely successful – effort to obtain the
outtakes of the film and related materials through applications
under 28 U.S.C. § 1782. Id. Chevron contends that the
outtakes show widespread fraud by the plaintiffs’ attorneys
and the Ecuadorian judiciary. Id. at 237. Chevron presented
            REPUBLIC OF ECUADOR V. MACKAY                     7

this evidence to the Lago Agrio court, but the court continued
to rely on the independent expert’s data and returned the
substantial judgment against Chevron. Id. One of Chevron’s
responses to the Lago Agrio action was a demand for
arbitration against the Republic pursuant to the bilateral
investment treaty between the United States and Ecuador
(“BIT Arbitration”). Berlinger, 629 F.3d at 303.

                               B

    On June 3, 2011, the Applicants filed a § 1782 application
seeking discovery from Mackay in the Eastern District of
California for use in the BIT Arbitration (the “Mackay”
action). They filed a similar application in the Northern
District of California on June 21, 2011, seeking discovery
from Kelsh and his former employer, Exponent, Inc. (the
“Kelsh” action). Chevron intervened in both actions.

    Mackay and Kelsh both served as Chevron’s experts in
the Lago Agrio action. Mackay is an adjunct professor at the
University of California-Davis who offered opinions
regarding the state of the soil and groundwater in the affected
areas, as well as the parties’ respective sampling and analysis.
Kelsh is an epidemiologist who submitted reports rebutting
the independent expert’s assessment regarding health
problems allegedly caused by Texaco’s operations. Chevron
submitted reports from both experts to the tribunal in the BIT
Arbitration. The Applicants contend that the discovery will
show that Chevron and its experts engaged in selective
sampling to achieve favorable results.

   Both district courts granted the § 1782 applications.
Chevron subsequently produced hundreds of thousands of
pages of documents but also withheld thousands of
8            REPUBLIC OF ECUADOR V. MACKAY

documents, asserting that they were privileged. The
Applicants objected to Chevron’s privilege claims, and the
parties eventually raised their disputes with the district courts.

    In the Mackay action, the magistrate judge found that
Chevron was required to produce all documents listed on its
privilege log other than Mackay’s draft reports and certain
“[c]ommunications directly between Dr. Mackay and
counsel.” The district court denied Chevron’s motion for
reconsideration.

   In the Kelsh action, the magistrate judge found that
Chevron did not have to produce draft reports, draft
worksheets, communications among Kelsh and his assistants,
or communications between Kelsh or his assistants and
Chevron attorneys. In re Republic of Ecuador (Kelsh),
280 F.R.D. 506, 512–14 (N.D. Cal. 2012). The magistrate
judge, however, otherwise ordered Chevron to produce the
documents it was withholding. Id. at 516. The district court
subsequently affirmed the magistrate judge’s order. Chevron
now appeals, and we have jurisdiction pursuant to 28 U.S.C.
§ 1291. See In re Premises Located at 840 140th Ave. NE,
634 F.3d 557, 565–66 (9th Cir. 2011).

                                II

     We typically review a district court’s discovery rulings
for abuse of discretion. R & R Sails, Inc. v. Ins. Co. of Pa.,
673 F.3d 1240, 1245 (9th Cir. 2012). However, where the
question is not whether the district court properly exercised
its discretion under a federal rule, but rather turns on the legal
issue of whether the court properly interpreted the rule’s
requirements, we review that question de novo. Whittlestone,
Inc. v. Handi-Craft Co., 618 F.3d 970, 973 (9th Cir. 2010).
            REPUBLIC OF ECUADOR V. MACKAY                     9

                              III

    Chevron argues that the plain language of Rule 26(b)(3)
generally protects expert materials as trial preparation
materials prepared “by or for” a party or a party’s
representative. It urges us to confine our review to the text of
the rule but contends that even if we look beyond it, the notes
of the Advisory Committee on the Federal Rules of Civil
Procedure support its interpretation. Chevron makes no
arguments specific to the documents at issue or the experts
involved in these proceedings; rather, the crux of Chevron’s
argument is that Rule 26(b)(3) always provides presumptive
protection for all testifying expert materials because they are
necessarily prepared “by or for” a party or its representative.

    We apply the “traditional tools of statutory construction”
to interpret the federal rules. See United States v. Petri,
731 F.3d 833, 839 (9th Cir. 2013) (quoting Beech Aircraft
Corp. v. Rainey, 488 U.S. 153, 163 (1988)), cert. denied,
134 S. Ct. 681 (2013). “The first step in construing the
meaning of a statute is to determine whether the language at
issue has a plain meaning.” McDonald v. Sun Oil Co.,
548 F.3d 774, 780 (9th Cir. 2008). “When interpreting a
statute, words and phrases must not be read in isolation, but
with an eye toward the ‘purpose and context of the statute.’”
Petri, 731 F.3d at 839 (quoting Dolan v. U.S. Postal Serv.,
546 U.S. 481, 486 (2006)). An interpretation that gives effect
to every clause is generally preferable to one that does not.
Cf. Marx v. Gen. Revenue Corp., 133 S. Ct. 1166, 1177
(2013). Additionally, “[i]t is a ‘cardinal rule of statutory
interpretation that no provision should be construed to be
entirely redundant.’” United States v. $133,420.00 in U.S.
Currency, 672 F.3d 629, 643 (9th Cir. 2012) (quoting Spencer
10          REPUBLIC OF ECUADOR V. MACKAY

Enters., Inc. v. United States, 345 F.3d 683, 691 (9th Cir.
2003)) (internal quotation marks omitted).

    Where “the statute’s language is plain” we do not
consider “the legislative history or any other extrinsic
material.” Kwai Fun Wong v. Beebe, 732 F.3d 1030, 1042
(9th Cir. 2013) (en banc) (quoting Exxon Mobile Corp. v.
Allapattah Servs., Inc., 545 U.S. 546, 568 (2005), and
Hartford Underwriters Ins. Co. v. Union Planters Bank, N.A.,
530 U.S. 1, 6 (2000)). “Thus, our inquiry begins with the
statutory text, and ends there as well if the text is
unambiguous.” McDonald, 548 F.3d at 780 (quoting BedRoc
Ltd., LLC v. United States, 541 U.S. 176, 183 (2004)). To
determine whether there is an ambiguity, we must assess
whether there is “an uncertainty of meaning or intention.” Id.
at 781 (citation and alteration marks omitted).

    The federal procedural and evidentiary rules are
accompanied by a unique form of legislative history. The
advisory committees draft and recommend rule changes to the
Judicial Conference. 28 U.S.C. § 2073(a)(2). If adopted by
the Supreme Court, the recommendations become law absent
Congressional action. See §§ 2072(a), 2074(a). Along with
their recommended rule changes, the advisory committees
provide explanatory notes. See 28 U.S.C. § 2073(d). As the
explanatory notes are contemporaneously drafted by the same
entity charged with drafting the rules, they are a particularly
reliable indicator of legislative intent. See United States v.
Vonn, 535 U.S. 55, 64 n.6 (2002) (“In the absence of clear
legislative mandate, the Advisory Committee Notes provide
a reliable source of insight into the meaning of a Rule,
especially when, as here, the rule was enacted precisely as the
Advisory Committee proposed.”). We have accordingly
observed that “[a]lthough Advisory Committee notes ‘do not
              REPUBLIC OF ECUADOR V. MACKAY                          11

foreclose judicial consideration’ of a rule’s validity and
meaning, ‘the construction given by the Committee is of
weight.’” Petri, 731 F.3d at 839 (quoting Schiavone v.
Fortune, 477 U.S. 21, 31 (1986)) (internal quotation marks
omitted). We have frequently relied on the advisory
committees’ notes for guidance. E.g., id. (clarifying any
ambiguity in Federal Rule of Criminal Procedure 32 with
reference to the notes); Summers v. Delta Air Lines, Inc.,
508 F.3d 923, 926 (9th Cir. 2007) (indicating that the
Advisory Committee’s note “guides our interpretation of
[Federal Rule of Civil Procedure] 50”); United States v.
Saeteurn, 504 F.3d 1175, 1180 (9th Cir. 2007) (“We look to
Advisory Committee Notes when interpreting a federal rule
for ‘guidance and insight.’”).

                                  A

                                   1

    We thus begin our analysis with the text of the rule. Rule
26 is titled, “Duty to Disclose; General Provisions Governing
Discovery.” Fed. R. Civ. P. 26. It sets forth, at some length,
the framework for civil disclosure and discovery. Rule 26(a)
sets out the requirements for parties’ mandatory disclosures,
including initial disclosures, expert disclosures, and other
pretrial disclosures. Among other things, parties must reveal
the identity of expert witnesses as part of their mandatory
disclosures, and most experts are required to submit reports
which must include “the facts or data considered by” the
expert in forming his or her opinions.1 Fed. R. Civ. P.


  1
    This requirement applies to testifying experts retained or specially
employed to provide expert testimony in the case or an employee whose
duties regularly involve providing expert testimony. Fed. R. Civ. P.
12            REPUBLIC OF ECUADOR V. MACKAY

26(a)(2)(A)–(B). Rule 26(b) then sets out the scope of
discovery. We have previously recognized that the scope of
permissible discovery under Rule 26 is “broad.” See Shoen
v. Shoen, 5 F.3d 1289, 1292 (9th Cir. 1993). The rule,
however, does provide some limitations on discovery, such as
protection for “trial preparation” materials as well as certain
expert materials.

     Rule 26(b)(3) is titled “Trial Preparation: Materials” and
extends protection to “documents and tangible things”
prepared “by or for” a party or its representative (“including
the . . . party’s attorney, consultant, surety, indemnitor,
insurer, or agent”) “in anticipation of litigation or for trial.”
Fed. R. Civ. P. 26(b)(3)(A). A party may still obtain
discovery of trial preparation materials under Rule 26(b)(3)
if they are otherwise discoverable and the party shows that it
has a “substantial need” for the materials and “cannot,
without undue hardship, obtain their substantial equivalent by
other means.” Fed. R. Civ. P. 26(b)(3)(A). To the extent that
a court orders discovery of trial preparation materials under
the rule, “it must protect against disclosure of the mental
impressions, conclusions, opinions, or legal theories of a
party’s attorney or other representative concerning the
litigation.” Fed. R. Civ. P. 26(b)(3)(B).




26(a)(2)(B). Parties must also disclose the subject matter and a summary
of facts and opinions for testifying experts who fall outside the report
requirement. Fed. R. Civ. P. 26(a)(2)(C). These experts typically include
treating physicians or a party’s employees who do not regularly provide
expert testimony. See N. Lee Cooper & Scott S. Brown, Selection of
Experts, Expert Disclosure and the Pretrial Exclusion of Expert
Testimony, in 3 Robert L. Haig, Business and Commercial Litigation in
Federal Courts § 28:10 (3d ed. 2012).
            REPUBLIC OF ECUADOR V. MACKAY                    13

     Rule 26(b)(4) is titled “Trial Preparation: Experts” and
provides that parties may depose testifying experts. Fed. R.
Civ. P. 26(b)(4)(A). It further provides that Rule 26(b)(3)
“protect[s] drafts of any report or disclosure required under
[the rule], regardless of the form in which the draft is
recorded.” Fed. R. Civ. P. 26(b)(4)(B). Trial preparation
protection also extends to “communications between the
party’s attorney and any [expert who must provide a report]
regardless of the form of the communications except to the
extent that the communications”: (i) relate to the expert’s
compensation; (ii) identify “facts or data” provided by the
attorney that the expert considered; or (iii) “identify
assumptions that the party’s attorney provided and that the
expert relied on in forming” his or her opinions. Fed. R. Civ.
P. 26(b)(4)(C). Facts known to, or opinions held by, an
expert retained “in anticipation of litigation or to prepare for
trial and who is not expected” to testify at trial (sometimes
known as a “consulting” expert) are ordinarily exempt from
discovery absent a showing of “exceptional circumstances.”
Fed. R. Civ. P. 26(b)(4)(D).

                               2

    Chevron argues that the text of Rule 26(b)(3), which
protects materials prepared “by or for” a party or its
“representative,” applies to expert materials that do not fall
within the attorney-expert communication or draft report
protections under Rule 26(b)(4). It contends that there are no
applicable exceptions beyond the limited requirements for
disclosure (e.g., “facts or data”) and specific exempted
categories of attorney-expert communications. Chevron
further argues that the disputed documents do not fall within
those exceptions and thus, the general provisions of Rule
26(b)(3) protects them from discovery.
14          REPUBLIC OF ECUADOR V. MACKAY

    The basic structure of the rule contradicts Chevron’s
argument. Rule 26(b)(3) extends protection to “Materials.”
Rule 26(b)(4) then separately provides some protection for
“Experts.” This strongly suggests that experts were intended
to be treated separately from the “materials” protected under
Rule 26(b)(3). Indeed, the fact that the Committee used the
term “expert” in Rule 26(b)(4) but not in the list of
representatives in Rule 26(b)(3) suggests that the omission of
“experts” in the text of Rule 26(b)(3) was intentional.
Hinchee, 2013 WL 6655490, at *6.

    However, there is also some textual support for the
argument that Rule 26(b)(3) can apply to testifying experts.
The phrase “by or for” and the term “representative” are
somewhat broad on their face. Arguably, testifying experts
prepare their analyses and supporting materials “for” the
parties that retain them. Indeed, this expansive language led
the First Circuit to conclude that a document prepared by a
testifying expert was covered by the rule. Sprague v.
Director, 688 F.2d 862, 868–70 (1st Cir. 1982) (concluding
that a letter prepared by medical expert “for” counsel was
protected by the work product doctrine). There are also
cross-references within Rule 26(b)(3) and Rule 26(b)(4)
which reflect a degree of interrelationship. See Fed. R. Civ.
P. 26(b)(3)(A) (indicating that, “subject to Rule 26(b)(4),”
materials otherwise protected under Rule 26(b)(3)(A) may be
discovered in certain circumstances); Fed. R. Civ. P.
26(b)(4)(B)–(C) (indicating that draft reports and attorney-
expert communications are generally protected by “Rules
26(b)(3)(A) and (B)”). The cross-references could be read to
suggest that Rule 26(b)(3) protection would otherwise apply
to experts if not for Rule 26(b)(4). See In re Cendent Corp.
Sec. Litig., 343 F.3d 658, 665 (3d Cir. 2003) (quoting
Bogosian v. Gulf Oil Corp., 738 F.2d 587, 594 (3d Cir.
            REPUBLIC OF ECUADOR V. MACKAY                   15

1984)). Nonetheless, although the language of Rule 26(b)(3)
and the cross-references do imply that there can be some
overlap between the protections for “Materials” and
“Experts,” they do not necessarily indicate that all expert
materials are always protected by Rule 26(b)(3).

    Indeed, the explicit protections for draft reports and
attorney-expert communications under Rule 26(b)(4) would
be redundant under Chevron’s interpretation of the rule.
Chevron suggests that these provisions are not redundant
because they: (a) extend protection to “facts or data” that
would otherwise have to be disclosed within draft reports;
and (b) set forth the exceptions to the explicit protection for
attorney-expert communications. This is implausible. If that
had been the Committee’s intent, it would have been much
simpler and clearer for it to declare that all expert materials
are protected as trial preparation materials and then set forth
exceptions to that general rule.

    Thus, if we were to make our decision based on the text
alone, we would conclude that Rule 26(b)(3)’s protection
does not extend to all testifying experts. Nonetheless, giving
Chevron the benefit of the doubt, we will assume for the
purposes of argument that the text’s meaning is ambiguous,
and accordingly, we look beyond the text itself.

                              B

    We proceed to review the historical context of the rule,
substantially aided by the Advisory Committee’s notes. The
work product doctrine is a “qualified immunity from
discovery” that attempts to balance “the necessity of
protecting an attorney’s preparation under the adversary
system, and the policy of full and open discovery underlying
16           REPUBLIC OF ECUADOR V. MACKAY

the” rules. Patrick E. Higginbotham, Duty to Disclose;
General Provisions Governing Discovery in 6 James Wm.
Moore, Moore’s Federal Practice § 26.70[1] at 26-434 to 26-
435 (3d ed. 2013) [hereinafter “Moore’s”]. The doctrine
evolved out of the Supreme Court’s seminal decision in
Hickman v. Taylor, 329 U.S. 495 (1947).

     In Hickman, the petitioner made discovery requests
seeking memoranda prepared by the defendants’ attorney
memorializing witness interviews prepared after the
underlying accident but before the litigation commenced. Id.
at 498–99. The Supreme Court ruled that the information
was not discoverable because it fell “outside the arena of
discovery and [discovery would] contravene[] the public
policy underlying the orderly prosecution and defense of legal
claims.” Id. at 509–10. That policy reflected the necessity
“that a lawyer work with a certain degree of privacy, free
from unnecessary intrusion by opposing parties and their
counsel.” Id. at 510–11. Thus, “the [w]ork product of the
lawyer” is shown “in interviews, statements, memoranda,
correspondence, briefs, mental impressions, personal beliefs,
and countless other tangible and intangible ways.” Id. at 511
(internal quotation marks omitted). The Court indicated that
if this material was not protected from discovery, “much of
what is now put down in writing would remain unwritten”
and that “[a]n attorney’s thoughts . . . would not be his own.”
Id. The result of a contrary rule would be “[i]nefficiency,
unfairness[,] . . . sharp practices,” and a “demoralizing” effect
on the profession. Id.

    In Hickman’s wake, the 1970 and 1993 amendments to
Rule 26 addressed the work product doctrine and the scope of
expert discovery. Prior to the 1970 amendment, courts were
divided on whether expert materials were protected by the
              REPUBLIC OF ECUADOR V. MACKAY                        17

work product doctrine. Richard L. Marcus, Depositions and
Discovery in 8 Charles Alan Wright et al., Federal Practice
and Procedure § 2029 (3d ed. 2013). The 1970 amendment
added provisions allowing for discovery of information held
by testifying experts and partially codifying the work product
doctrine. Fed. R. Civ. P. 26(b) advisory committee’s notes
(1970 amendment); United States v. Deloitte LLP, 610 F.3d
129, 136 (D.C. Cir. 2010).2 The primary reason for
permitting discovery of testifying experts (as opposed to
consulting experts) was to allow “the adverse party to prepare
for effective cross-examination and rebuttal.” Wright et al.,
supra, § 2032 (citing Fed. R. Civ. P. 26 advisory committee’s
notes (1970 amendment)). The Committee explained that if
this discovery were foreclosed, “then the narrowing of issues
and elimination of surprise which discovery normally
produces are frustrated.” Fed. R. Civ. P. 26(b)(4) advisory
committee’s notes (1970 amendment). The Committee also
indicated that the creation of the rule was intended to “reject
as ill-considered the decisions which have sought to bring
expert information within the work-product doctrine.” Id.;
accord United States v. Meyer, 398 F.2d 66, 73–74 (9th Cir.
1968).

    In 1993, the Committee added the provisions requiring
most testifying experts to prepare reports including various
disclosures. Fed. R. Civ. P. 26(a)(2) advisory committee’s
notes (1993 amendments). The Committee explained:

        The report is to disclose the data and other
        information considered by the expert and any


 2
   Although Rule 26(b)(3) is focused on documents and tangible things,
Hickman protects intangible things independent of the rule. Deloitte,
610 F.3d at 136 (citing 329 U.S. at 512–13).
18             REPUBLIC OF ECUADOR V. MACKAY

         exhibits or charts that summarize or support
         the expert’s opinions. Given 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.

Id.

    The requirement 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 “[s]ubject to” provisions requiring expert
depositions led many courts to conclude that “any material
given by an attorney to an expert [wa]s discoverable,”
including opinion work product.3 See Moore’s, supra,
§ 26.80[1][a] at 26-477 to 26-478. 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 “requir[ing] disclosure of more than


  3
     “Opinion work product” represents the core types of work product
protected under Hickman, namely an attorney’s mental impressions,
conclusions, opinions, or legal theories developed in anticipation of
litigation. See Deloitte, 610 F.3d at 136. It “is virtually undiscoverable.”
Id. at 135 (quoting Director v. Vinson & Elkins, LLP, 124 F.3d 1304, 1307
(D.C. Cir. 1997)).
            REPUBLIC OF ECUADOR V. MACKAY                  19

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 “requir[ed] disclosure of all
information provided to testifying experts.” Id. (internal
quotation marks omitted); accord Elm Grove Coal Co. v.
Director, 480 F.3d 278, 301 (4th Cir. 2007); In re Pioneer
Hi-Bred Int’l, Inc., 238 F.3d 1370, 1375 (Fed. Cir. 2001).

    Against that backdrop, the Advisory Committee explained
the impetus of the 2010 amendments as follows:

       Many courts read [the 1993 version of] the
       disclosure provision to authorize discovery of
       all communications between counsel and
       expert witnesses and all draft reports. 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.
20          REPUBLIC OF ECUADOR V. MACKAY

Fed. R. Civ. P. 26 advisory committee’s notes (2010
amendments).

    Accordingly, the amended rule “provide[s] work-product
protection against discovery regarding draft expert
disclosures or reports and – with three specific exceptions –
communications between expert witnesses and counsel.”
Fed. R. Civ. P. 26 advisory committee’s notes (2010
amendments). With respect to the disclosure obligations, the
notes indicate that the requirements should “be interpreted
broadly” to encompass “any material considered by the
expert, from whatever source, that contains factual
ingredients” but to exclude the “theories or mental
impressions of counsel.” Fed. R. Civ. P. 26(a)(2)(B) advisory
committee’s notes (2010 amendments). Notably, “[t]he
disclosure obligation extends to any facts or data ‘considered’
by the expert in forming the opinions to be expressed, not
only those relied upon by the expert.” Id.; see also Allstate
Ins. Co. v. Electrolux Home Prods., Inc., 840 F. Supp. 2d
1072, 1080 (N.D. Ill. 2012) (indicating that discoverable
“factual” information includes material that the expert
“considered” – i.e., was provided or otherwise exposed to in
the course of developing his or her opinions – rather than just
the narrower spectrum of material that the expert “relied
upon”). The prior version of the rule had required the
disclosure of “data or other information,” but the Committee
revised this to “facts or data” to “alter the outcome in cases
that have relied on the 1993 formulation in requiring
disclosure of all attorney-expert communications and draft
reports.” Fed. R. Civ. P. 26(a)(2)(B) advisory committee’s
notes (2010 amendments).

   Rule 26(b)(4)’s protections for draft reports and attorney-
expert communications “do not impede discovery about the
            REPUBLIC OF ECUADOR V. MACKAY                    21

opinions to be offered by the expert or the development,
foundation, or basis of those opinions.” Fed. R. Civ. P.
26(b)(4) advisory committee’s notes (2010 amendments).
Indeed, the scope of permissible “disclosure and discovery
otherwise allowed” remains “broad.” Fed. R. Civ. P. 26(b)(4)
advisory committee’s notes (2010 amendments). For
example, the rule allows for discovery of: (a) the testing of
material involved in litigation and notes concerning any such
testing; (b) alternative analyses, testing methods, or
approaches; and (c) “communications the expert had with
anyone other than the party’s counsel about the opinions
expressed.” Fed. R. Civ. P. 26(b)(4) advisory committee’s
notes (2010 amendments). However, discussions with
counsel about the “potential relevance of facts or data” and
more general discussions “about hypotheticals, or exploring
possibilities based on hypothetical facts” are protected. Id.
Thus, materials containing “factual ingredients” are
discoverable, while opinion work product is not discoverable.
See Fed. R. Civ. P. 26(a)(2)(B) advisory committee’s notes
(2010 Amendments).

                               C

    The historical evolution of the rule, its current structure,
and the Committee’s explanatory notes make clear that the
driving purpose of the 2010 amendments was to protect
opinion work product – i.e., attorney mental impressions,
conclusions, opinions, or legal theories – from discovery. See
1 Steven S. Gensler, Federal Rules of Civil Procedure: Rules
and Commentary Rule 26 cmt. & n.82 (2013) (indicating that
the Committee was attempting to “alter the outcome reached
in” cases such as Regional Airport Authority, 460 F.3d at
714). The protections for draft reports and attorney-expert
communications were targeted at the areas most vulnerable to
22             REPUBLIC OF ECUADOR V. MACKAY

the disclosure of opinion work product. The Committee thus
sought to acknowledge the reality that attorneys often feel
that it is extremely useful – if not necessary – to confer and
strategize with their experts. But there is no indication that
the Committee was attempting to do so at the expense of an
adversary’s ability to understand and respond to a testifying
expert’s analysis.4

    To the contrary, the Committee sought to balance the
competing policy considerations, including the need to
provide an adversary with sufficient information to engage in
meaningful cross-examination and prepare a rebuttal, on the
one hand, and the need to protect the attorney’s zone of
privacy to efficiently prepare a case for trial without incurring
the undue expense of engaging multiple experts, on the other.
There is no indication that the Committee intended to expand
Rule 26(b)(3)’s protection for trial preparation materials to
encompass all materials furnished to or provided by testifying
experts, which would unfairly hamper an adverse party’s
ability to prepare for cross-examination and rebuttal. We
accordingly reject Chevron’s argument.




 4
   Indeed, we note that any ordinary work product protection (i.e., for trial
preparation materials prepared by non-attorneys that do not reflect an
attorney’s mental impressions, conclusions, opinions, or legal theories)
would typically be waived where the materials are disclosed to a testifying
expert. See United States v. Nobles, 422 U.S. 225, 239 (1975) (concluding
that although the work product protection would otherwise apply to an
investigator’s report, the defendant “by electing to present the investigator
as a witness, waived the privilege with respect to matters covered in his
testimony”); Meyer, 398 F.2d at 74 (emphasizing that the discovery of
appraisers’ work in a condemnation action was permissible because the
appraisers were expert witnesses who were expected to testify at trial).
            REPUBLIC OF ECUADOR V. MACKAY                 23

                             IV

     We conclude that Rule 26(b)(3) does not provide
presumptive protection for all testifying expert materials as
trial preparation materials. The 2010 amendments did not
fundamentally restructure Rule 26 to do so. Our conclusion
is fatal to Chevron’s argument.              Accordingly, we
independently arrive at the same result reached by our sister
circuits. See Hinchee, 2013 WL 6655490, at *1; Bjorkman,
735 F.3d at 1180. As Chevron has forsworn any challenge to
the district courts’ specific assessments of the various
categories of documents in dispute, we also do not reach
those aspects of the district courts’ decisions.

   AFFIRMED.
