                 FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


TRUE HEALTH CHIROPRACTIC,                  No. 16-17123
INC.; MCLAUGHLIN
CHIROPRACTIC ASSOCIATES,                    D.C. No.
INC., individually and as              4:13-cv-02219-HSG
representatives of a class of
similarly situated persons,
             Plaintiffs-Appellants,         OPINION

                v.

MCKESSON CORPORATION;
MCKESSON TECHNOLOGIES,
INC.,
        Defendants-Appellees.


      Appeal from the United States District Court
        for the Northern District of California
    Haywood S. Gilliam, Jr., District Judge, Presiding

        Argued and Submitted October 17, 2017
              San Francisco, California

                     Filed July 17, 2018

  Before: Michael Daly Hawkins, William A. Fletcher,
        and Richard C. Tallman, Circuit Judges.

              Opinion by Judge W. Fletcher
2        TRUE HEALTH CHIROPRACTIC V. MCKESSON

                            SUMMARY*


        Telephone Consumer Protection Act / Class
                     Certification

   The panel affirmed in part and reversed in part the district
court’s denial of class certification in an action under the
Telephone Consumer Protection Act.

    Appellants sought to represent a class of plaintiffs who
allegedly received unsolicited faxed advertisements from
defendants in violation of the TCPA. The district court
denied class certification on the ground that under Fed. R.
Civ. P. 23(b)(3), individual issues related to affirmative
defenses would predominate over issues common to the class.
These “consent defenses” alleged that putative class members
in various ways gave defendants “prior express invitation or
permission” to send the faxes.

    The panel concluded that the district court did not impose
an “ascertainability” or administrative feasibility requirement
for class certification. Agreeing with the Sixth Circuit, the
panel held that there is no requirement that all faxes, whether
consented or not, must contain an “opt-out” notice because
the FCC’s Solicited Fax Rule has been held invalid by the
D.C. Circuit.

    The panel nonetheless concluded that the district court
erred in part in holding that appellants’ proposed class or
subclasses failed to satisfy the predominance requirement of

    *
      This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
       TRUE HEALTH CHIROPRACTIC V. MCKESSON                3

Rule 23(b)(3). The panel held that in light of Van Patten v.
Vertical Fitness Grp., LLC, 847 F.3d 1037 (9th Cir. 2017)
(holding that “express consent” is an affirmative defense to
a claim brought under 47 U.S.C. § 227(b)(1)(A), a provision
of the TCPA dealing with unsolicited telephone calls), “prior
express invitation or permission” under § 227(b)(1)(C) is an
affirmative defense on which the defendant bears the burden
of proof. The panel affirmed the district court’s denial of
class certification with respect to one possible subclass and
reversed the district court’s holding that other possible
subclasses could not satisfy the predominance requirement.
The panel held that one subclass would satisfy predominance,
and it remanded for a determination whether another
subclass would also satisfy the requirement. The panel also
remanded to allow the district court to address the
requirements of Rule 23(a).


                        COUNSEL

Glenn L. Hara (argued), Anderson and Wanca, Rolling
Meadows, Illinois; Willem F. Jonckheer, Schubert Jonckheer
& Kolbe LLP, San Francisco, California; for Plaintiffs-
Appellants.

Joseph R. Palmore (argued) and Seth W. Lloyd, Morrison &
Foerster LLP, Washington, D.C.; Ben Patterson and Tiffany
Cheung, Morrison & Foerster LLP, San Francisco, California;
for Defendants-Appellees.
4       TRUE HEALTH CHIROPRACTIC V. MCKESSON

                         OPINION

W. FLETCHER, Circuit Judge:

    Appellants True Health Chiropractic and McLaughlin
Chiropractic (“True Health”) seek to represent a class of
plaintiffs who allegedly received unsolicited faxed
advertisements from appellees McKesson Corporation and
McKesson Technologies, Inc. (“McKesson”) between
September 2009 and May 2010, in violation of the Telephone
Consumer Protection Act of 1991 (“TCPA”). The district
court denied class certification on the ground that individual
issues related to McKesson’s affirmative defenses would
predominate over issues common to the class. See Fed. R.
Civ. P. 23(b)(3). We granted True Health’s request for
permission to appeal the order pursuant to Federal Rule of
Civil Procedure 23(f). We affirm in part, reverse in part, and
remand.

                       I. Background

               A. True Health’s TCPA Claim

    The TCPA forbids certain unsolicited advertisements sent
via phone or facsimile (“fax”). 47 U.S.C. § 227(b)(1). In
enacting the TCPA, “Congress intended to remedy a number
of problems associated with junk faxes, including the cost of
paper and ink, the difficulty of the recipient’s telephone line
being tied up, and the stress on switchboard systems.” Imhoff
Inv., L.L.C. v. Alfoccino, Inc., 792 F.3d 627, 633 (6th Cir.
2015). The TCPA makes it unlawful to send “unsolicited
advertisement[s]” via fax machine. 47 U.S.C. § 227(b)(1)(C).
An advertisement is unsolicited if it includes “any material
advertising the commercial availability or quality of any
       TRUE HEALTH CHIROPRACTIC V. MCKESSON                 5

property, goods, or services which is transmitted to any
person without that person’s prior express invitation or
permission, in writing or otherwise.” Id. § 227(a)(5). But
unsolicited advertisements may be sent if (1) the sender and
recipient have “an established business relationship,” (2) the
recipient voluntarily provided his or her contact
information to the sender either directly or indirectly
through “a directory, advertisement, or site on the Internet,”
and (3) the “unsolicited advertisement contains” an opt-out
notice meeting certain statutory requirements. Id.
§ 227(b)(1)(C)(i)–(iii). In 2006, the Federal Communications
Commission (“FCC”) promulgated a regulation requiring that
companies include opt-out notices in solicited as well as
unsolicited advertisements (the “Solicited Fax Rule”).
47 C.F.R. § 64.1200(a)(4)(iv). Eleven years later, the D.C.
Circuit held the Solicited Fax Rule invalid. See Bais Yaakov
of Spring Valley v. FCC, 852 F.3d 1078, 1083 (D.C. Cir.
2017).

    True Health’s Second Amended Complaint (“SAC”)
alleges that McKesson sent to named plaintiffs and other
putative class members unsolicited fax advertisements
without their prior express permission or invitation, and
without opt-out notices, in violation of 47 U.S.C.
§ 227(b)(1)(C) and 47 C.F.R. § 64.1200(a)(4)(iv). According
to the SAC, McKesson sent the faxes at issue after having
received a May 9, 2008, citation from the FCC warning it
against sending unsolicited advertising by fax. The citation
stated, “It has come to our attention that your company . . .
apparently sent one or more unsolicited advertisements to
telephone facsimile machines in violation of Section
227(b)(1)(C) of the [TCPA].” In its answer to the SAC,
McKesson alleged that True Health and other putative class
members in various ways gave McKesson “prior express
6      TRUE HEALTH CHIROPRACTIC V. MCKESSON

invitation or permission” to send the faxes. 47 U.S.C.
§ 227(a)(5). For ease of reference, we will refer to this as
McKesson’s “consent defenses.”

                       B. Discovery

    During discovery, True Health requested that McKesson
produce “[a]ll Documents indicating that any person gave
prior express invitation or permission to receive facsimile
transmissions of any [McKesson advertisements].” True
Health also asked McKesson to identify “each type of act that
Defendants believe demonstrates a recipient’s express
permission to receive faxes” and to list which class members
consented in each of the ways identified.

    McKesson responded by listing three groups of consent
defenses that it claimed relieved it of TCPA liability.
McKesson attached to its response three exhibits, which
corresponded to the three groups of asserted consent
defenses, listing putative class members who purportedly
consented in the specified manners. According to McKesson,
each exhibit contains the “name and contact information
(where available)” of faxes for each asserted consent defense.
The exhibits are not in the record, but McKesson described
the consent defenses it asserted against the putative class
members in each exhibit.

    Exhibit A lists putative class members that, according to
McKesson, (1) provided their fax numbers when registering
a product purchased from Physician Practice Solutions
(“PPS”), a business unit of McKesson Technologies, and/or
(2) entered into software-licensing agreements, called End
User License Agreements (“EULAs”). Exhibit A, which
        TRUE HEALTH CHIROPRACTIC V. MCKESSON                  7

contains 11,979 unique fax numbers, lists all of the putative
class members on whose behalf True Health brings suit.

    Exhibit B, a subset of Exhibit A, lists putative class
members that, according to McKesson, (1) “check[ed] a box
during their software registration that indicated their express
permission to be sent faxes as a preferred method of
communication to receive promotional information,”
(2) “complete[d] a written consent form whereby they further
provided their express permission to receive faxes,” and/or
(3) “confirm[ed],” via phone, “that they would like to
continue to receive faxes and/or would like to change their
communication method preferences” during an “outreach
program to update contact information of certain preexisting
customers.” The putative class members listed in Exhibit B
were identified “based on information currently residing in [a
PPS internal database].” McKesson stated that Exhibit B may
not list every putative class member that consented in the
specified ways: “Other recipients of those faxes may have
also indicated consent through one or more of the methods
described above before receiving such faxes, but limitations
of the database do not allow Defendants to identify those
specific customers without individualized inquiries.” Exhibit
B lists 2,701 unique fax numbers.

    Exhibit C, another subset of Exhibit A, lists putative class
members that, according to McKesson, gave consent in
individual “oral or email” communications with McKesson
sales representatives. McKesson stated,

       “Often, because of . . . long-standing and well
       developed relationships, PPS sales
       representatives would learn and know that a
       particular customer exclusively preferred to
8      TRUE HEALTH CHIROPRACTIC V. MCKESSON

       receive faxes over, for example, emails.
       Other times, PPS sales representatives would
       notate that customer’s preference for faxes by
       making a note that might be linked to the
       [PPS internal database]. . . . In some
       instances, customers specifically requested
       that they receive promotional information
       exclusively via fax.”

McKesson stated further, as it did with respect to Exhibit B,
that Exhibit C may not list every putative class member that
consented in the specified ways: “Other recipients of those
faxes may have also indicated invitation or permission
through oral communications with their PPS representatives,
and individualized inquiries must be conducted to specifically
identify those customers.” Exhibit C lists fifty-five unique
fax numbers.

    Regarding Exhibit C, McKesson submitted a declaration
from sales representative Jeffery Paul and deposition excerpts
of former sales representative Kari Holloway. Mr. Paul
stated in his declaration that he “became familiar with [his]
customers and . . . how to communicate with them[,]” and
claimed that “[m]any customers specifically asked [him] to
send them faxes instead of using alternative ways to
communicate, such as emails.” He further stated that “[i]t
was commonplace for customers to ask [him] on a daily basis
to send them information by fax, including information on
promotions or upgrades[,]” and that “[c]ustomers specifically
asked [him] to fax them information on discounts,
promotions, and/or upgrades when available[.]” Ms.
Holloway stated in her deposition, “Our existing customers
oftentimes would request us to send faxes specifically.” She
also claimed, “The sales representatives had a decent handle
         TRUE HEALTH CHIROPRACTIC V. MCKESSON                           9

on who their customers were. It wasn’t an enormous number
so they knew the people and they knew the ways they would
like to be communicated with.”

                 C. Denial of Class Certification

    True Health moved under Rule 23(b)(3) to certify the
class of “[a]ll persons or entities who received faxes from
‘McKesson’ from September 2, 2009, to May 11, 2010,
offering [certain McKesson services], where the faxes do not
inform the recipient of the right to ‘opt out’ of future faxes.”
McKesson opposed the motion, contending, inter alia, that
the proposed class did not satisfy the Rule 23(b)(3)
predominance requirement, given that the consent defenses
available against putative class members listed in Exhibits A,
B, and C could not be resolved without individualized
inquiries. True Health argued that the predominance
requirement was met for the entire putative class, but
requested in the alternative that the district court certify
subclasses. At oral argument on the motion for class
certification, the district court raised sua sponte the possibility
of dividing the class into three subclasses, each corresponding
to the putative class members in Exhibits A, B, and C.

    The district court denied class certification, holding that
individual issues in McKesson’s various consent defenses
defeated predominance under Rule 23(b)(3). The court’s
order did not address True Health’s request for subclasses.
True Health appealed.1




     1
       True Health also moved for certification under Rule 23(b)(2). The
district court denied the motion. True Health does not appeal that ruling.
10     TRUE HEALTH CHIROPRACTIC V. MCKESSON

                   II. Standard of Review

     We review orders denying class certification as well as
the underlying factual determinations for abuse of discretion.
Jimenez v. Allstate Ins. Co., 765 F.3d 1161, 1164 (9th Cir.
2014) (citing Berger v. Home Depot USA, Inc., 741 F.3d
1061, 1066 (9th Cir. 2014), abrogated on other grounds by
Microsoft Corp. v. Baker, 137 S. Ct. 1702 (2017)); Mazza v.
Am. Honda Motor Co., 666 F.3d 581, 588 (9th Cir. 2012)
(citing Zinser v. Accufix Research Inst., Inc., 253 F.3d 1180,
1186 (9th Cir. 2001)). A district court abuses its discretion
when it applies the wrong legal standard. Jimenez, 765 F.3d
at 1167 (citing Levya v. Medline Indust., Inc., 716 F.3d 510,
514 (9th Cir. 2013)). We review de novo the district court’s
application of the law to the facts. Mazza, 666 F.3d at 588
(citing United States v. Hinkson, 585 F.3d 1247, 1259 (9th
Cir. 2009) (en banc)).

                       III. Discussion

    True Health makes three arguments on appeal. First, it
argues that the district court erred in applying an
“ascertainability” requirement. Second, it argues that an opt-
out notice is required for all faxes, both solicited and
unsolicited, and that the district court erred in holding
otherwise. Third, it argues that the district court erred in
holding that True Health’s proposed class or subclasses fail
to satisfy the “predominance” requirement of Rule 23(b)(3).
We disagree with the first two arguments but agree with the
third. We discuss them in turn.
        TRUE HEALTH CHIROPRACTIC V. MCKESSON                  11

                     A. Ascertainability

    True Health argues that the district court erred in
imposing an ascertainability requirement for class
certification in violation of Briseno v. ConAgra Foods, Inc.,
844 F.3d 1121, 1124–25 (9th Cir. 2017). True Health’s
argument fails.

    In its order denying class certification, the district court
observed in passing that some courts have read an
ascertainability requirement into Rule 23. It later noted in a
parenthetical that another district court had denied
certification, in part, on ascertainability grounds. Neither of
these references to ascertainability show that the district court
ascribed to the view that a class must be ascertainable, much
less that the court applied such a requirement in this case.

    Nor did the court violate Briseno. In Briseno, the
defendant argued that a class must be “ascertainable” to be
certified under Rule 23. Briseno, 844 F.3d at 1124. We
understood defendant’s argument to be that identification of
class members must be “administratively feasible[.]” Id. at
1133. We held that there is no free-standing requirement
above and beyond the requirements specifically articulated in
Rule 23. Id. The district court’s order in this case does not
impose an administrative-feasibility requirement.

                  B. The Solicited Fax Rule

   True Health argues that under the FCC’s Solicited Fax
Rule, 47 C.F.R. § 64.1200(a)(4)(iv), both solicited and
unsolicited faxes are subject to the “opt-out” notice
requirement of 47 U.S.C. § 227(b)(1)(C)(iii). That is, True
Health argues that under the Solicited Fax Rule all
12     TRUE HEALTH CHIROPRACTIC V. MCKESSON

faxes—whether consented or not—must contain such a
notice. If True Health is right, variations in the manner in
which members of the proposed class may have given
consent are irrelevant in determining McKesson’s failure to
include opt-out notices in its faxes, and therefore such
variations are irrelevant to a determination of predominance
under Rule 23(b)(3).

    True Health’s argument fails because the Solicited Fax
Rule has been held invalid by the D.C. Circuit. The FCC
promulgated the Solicited Fax Rule in 2006. The FCC then
issued an order in 2014 interpreting the Solicited Fax Rule.
See Order, Petitions for Declaratory Ruling, Waiver, and/or
Rulemaking Regarding the Commission’s Opt-Out
Requirement for Faxes Sent with the Recipient’s Prior
Express Permission, 29 FCC Rcd. 13,998 (2014). In Bais
Yaakov, the D.C. Circuit vacated the 2014 FCC order on the
ground that the underlying Solicited Fax Rule was invalid:
“We hold that the FCC’s 2006 Solicited Fax Rule is unlawful
to the extent that it requires opt-out notices on solicited
faxes.” 852 F.3d at 1083.

    In Bais Yaakov, the D.C. Circuit decided multiple
petitions for review that had been consolidated and
transferred by the Judicial Panel on Multidistrict Litigation
(“JPML”). See Sandusky Wellness Ctr. v. ASD Specialty
Healthcare, 863 F.3d 460, 467 (6th Cir. 2017) (describing
procedural history of Bais Yaakov). When the JPML
consolidates challenges to an agency regulation and transfers
them to a court of appeals, the court to which they are
transferred becomes “the sole forum for addressing . . . the
validity of the FCC’s rules.” MCI Telecomms. Corp. v. U.S.
W. Commc’ns, 204 F.3d 1262, 1267 (9th Cir. 2000) (quoting
GTE S., Inc. v. Moirrison, 199 F.3d 733, 743 (4th Cir. 1999)).
         TRUE HEALTH CHIROPRACTIC V. MCKESSON                          13

The decision of that court is then binding on all circuits. See
Peck v. Cingular Wireless, LLC, 535 F.3d 1053, 1057 (9th
Cir. 2008).

    True Health argues that Bais Yaakov’s holding—that the
Solicited Fax Rule is invalid—is not binding on us because
the FCC’s 2006 Solicited Fax Rule was not directly under
review. True Health does not challenge the authority of the
court in Bais Yaakov to invalidate the Solicited Fax Rule in
the course of reviewing the FCC’s 2014 order, but it argues
that the only part of Bais Yaakov binding on this court was its
ruling vacating the 2014 order.

    Plaintiff Sandusky Wellness Center, represented by the
same counsel as True Health in this case, made essentially the
same argument to the Sixth Circuit last year. See Sandusky,
863 F.3d at 467–68. The Sixth Circuit disagreed with the
argument, and so do we. It is, of course, true that Bais
Yaakov reviewed a 2014 FCC order. But the validity of the
2014 order depended on the validity of the 2006 Solicited Fax
Rule, and the court in Bais Yaakov squarely held that the
underlying Solicited Fax Rule was invalid. We agree with
the reasoning of the Sixth Circuit and hold that we are bound
by Bais Yaakov.2



     2
       In a separate 2015 order, the FCC retroactively waived the Solicited
Fax Rule for more than one hundred companies, including McKesson.
See Order, Petitions for Declaratory Ruling and Retroactive Waiver of
47 C.F.R. § 64.1200(a)(4)(iv) Regarding the Commission’s Opt-Out
Notice Requirement for Faxes Sent with the Recipient’s Prior Express
Permission, 30 FCC Rcd. 8598, 8598, 8613 (2015). Because we hold that
we are bound by the D.C. Circuit’s decision holding that the Solicited Fax
Rule is invalid, we do not address the parties’ arguments concerning the
effect of the 2015 FCC order.
14      TRUE HEALTH CHIROPRACTIC V. MCKESSON

                       C. Predominance

     Finally, in the event that its Solicited Fax Rule argument
is rejected, True Health argues that the district court abused
its discretion in holding that McKesson’s consent defenses
foreclosed a finding of predominance under Rule 23(b)(3).
Specifically, True Health argues that the district court erred
in not certifying subclasses.

    As a preliminary matter, McKesson argues that True
Health has “forfeited” any argument that the district court
should have certified subclasses. According to McKesson,
“Plaintiffs . . . did not even make a cursory attempt” to
“satisfy [their] burden” to “show that any proposed subclass
complies with [the] requirements [of Rule 23].” We disagree.

    “Although no bright line rule exists to determine whether
a matter has been properly raised below, an issue will
generally be deemed waived on appeal if the argument was
not raised sufficiently for the trial court to rule on it.” Tibble
v. Edison Int’l, 843 F.3d 1187, 1193 (9th Cir. 2016) (en banc)
(quoting In re Mercury Interactive Corp. Sec. Litig., 618 F.3d
988, 992 (9th Cir. 2010)) (internal alteration omitted). In its
motion for class certification, True Health argued, assuming
the failure of its Solicited Fax Rule argument, that subclasses
should be certified. True Health wrote,

        “Defendants’ claims for prior express
        permission can easily be decided through
        creation of subclasses. For example, . . .
        Defendants admit their claim of express
        permission with respect to 39,495
        transmission to 7,760 fax numbers is that they
        obtained permission in software-registration
       TRUE HEALTH CHIROPRACTIC V. MCKESSON               15

       forms. The Court can easily decide whether
       listing a fax number on a software-registration
       form constitutes ‘prior express permission’ to
       receive fax advertisements at that number.”
       (Citations omitted.)

Combined with the discussion of subclasses that took place
during oral argument below, this was enough to alert the
court that subclasses were sought, to indicate how they might
be defined, and to preserve the issue for appeal.

     When certification is sought for a litigation class, the
predominance inquiry under Rule 23(b)(3) asks whether
“common questions present a significant aspect of the case
and they can be resolved for all members of the class in a
single adjudication[.]” Mazza., 666 F.3d at 589 (quoting
Hanlon v. Chrysler Corp., 150 F.3d 1011, 1022 (9th Cir.
1998)). The common questions must have the “capacity . . .
to generate common answers apt to drive the resolution of the
litigation.” Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338,
350 (2011) (quoting Richard A. Nagareda, Class Certification
in the Age of Aggregate Proof, 84 N.Y.U. L. Rev. 97, 132
(2009)) (emphasis omitted). Defenses that must be litigated
on an individual basis can defeat class certification. Id. at
367. Yet “[w]hen ‘one or more of the central issues in the
action are common to the class and can be said to
predominate, the action may be considered proper under Rule
23(b)(3) even though other important matters will have to be
tried separately, such as . . . some affirmative defenses
peculiar to some individual class members.’ ” Tyson Foods,
Inc. v. Bouaphakeo, 136 S. Ct. 1036, 1045 (2016) (quoting
7AA C. Wright, A. Miller & M. Kane, Federal Practice and
Procedure § 1778, at 123–24 (3d ed. 2005)). The party
seeking class certification has the burden of establishing
16      TRUE HEALTH CHIROPRACTIC V. MCKESSON

predominance. See Ellis v. Costco Wholesale Corp., 657 F.3d
970, 979 (9th Cir. 2011) (citing Zinser, 253 F.3d at 1186).

               1. Burden of Proof on Consent

    We begin with the question whether True Health or
McKesson bears the burden of proof on the issue of consent.
While the appeal in this case was pending, we decided Van
Patten v. Vertical Fitness Group, LLC, 847 F.3d 1037 (9th
Cir. 2017). There, we held that “express consent” is an
affirmative defense to a claim brought under a provision of
the TCPA dealing with unsolicited telephone calls, and that
the defendant bears the burden of proving such consent. Van
Patten, 847 F.3d at 1044; see also 47 U.S.C. § 227(b)(1)(A).
Section 227(b)(1)(C), at issue in our case and part of the same
section of the TCPA, does not use the term “express consent.”
But it clearly provides that consent is a defense with respect
to faxes, as does § 227(b)(1)(A) with respect to telephone
calls. The requirements of § 227(b)(1)(C) apply to
“unsolicited” faxes, which are defined as faxes sent “without
[the recipient’s] prior express invitation or permission.”
47 U.S.C. § 227(a)(5). We see no distinction between
“express consent” and “prior express invitation or
permission” that would affect which party bears the burden
of proving consent. We therefore hold that “prior express
invitation or permission” is an affirmative defense on which
McKesson bears the burden of proof.

   Putative class members, of course, retain the burden of
showing that the proposed class satisfies the requirements of
Rule 23, including the predominance requirement of Rule
23(b)(3). See Ellis, 657 F.3d at 979–80. But the burden of
proving consent strongly affects the analysis. Since
McKesson bears the burden, we assess predominance by
        TRUE HEALTH CHIROPRACTIC V. MCKESSON                 17

analyzing the consent defenses McKesson has actually
advanced and for which it has presented evidence. A
defendant can produce evidence of a predominance-defeating
consent in a variety of ways. See, e.g., Sandusky Wellness.,
863 F.3d at 468–70. But we do not consider the consent
defenses that McKesson might advance or for which it has
presented no evidence. See Bridging Communities Inc. v. Top
Flite Fin. Inc., 843 F.3d 1119, 1125 (6th Cir. 2016), cert.
denied, 138 S. Ct. 80 (2017) (“We are unwilling to allow such
‘speculation and surmise to tip the decisional scales in a class
certification ruling[.]’ ” (quoting Waste Mgmt. Holdings, Inc.
v. Mowbray, 208 F.3d 288, 298 (1st Cir. 2000)) . The consent
defenses that McKesson has advanced and for which it has
provided supporting evidence may be sufficiently similar or
overlapping to allow True Heath to satisfy the predominance
requirement of Rule 23(b)(3) with respect to those defenses.
If so, a class or subclass of plaintiffs to whom such defenses
apply may be certified, provided of course that the other
requirements of Rule 23 are also satisfied.

                        2. Subclasses

    True Health argues that three subclasses comprising the
putative class members identified in Exhibits A, B, and C
satisfy the predominance requirement of Rule 23(b)(3). We
agree as to part of Exhibit A; we disagree as to Exhibit C; and
we remand as to Exhibit B.

     Exhibit A lists all putative class members, including those
listed in Exhibits B and C. Their claims are based on faxes
sent to 11,979 unique fax numbers. If we remove from
Exhibit A all putative class members listed in Exhibits B and
C, McKesson has asserted only two consent defenses. First,
McKesson asserts that some of the remaining putative class
18      TRUE HEALTH CHIROPRACTIC V. MCKESSON

members gave consent by providing their fax numbers when
registering a product purchased from a subdivision of
McKesson. Second, McKesson asserts that some of them
gave consent by entering into software-licensing agreements,
or EULAs. We have examples of product registrations and
EULAs in the record. McKesson has provided no further
evidence relevant to these two defenses.

    So far as the record shows, there is little or no variation in
the product registrations and the EULAs. For both of these
asserted defenses, the predominance requirement of Rule
23(b)(3) is therefore satisfied. Consent, or lack thereof, is
ascertainable by simply examining the product registrations
and the EULAs. We therefore conclude that the claims of the
putative class members listed in Exhibit A that remain after
removing the claims in Exhibits B and C satisfy the
predominance requirement of Rule 23(b)(3).

    Exhibit C lists putative class members whose claims are
based on faxes sent to fifty-five unique fax numbers.
McKesson provided evidence in the district court that its
consent defenses to these claims would be based on
individual communications and personal relationships
between McKesson representatives and their customers. The
variation in such communications and relationships, as
evidenced by the declaration of Mr. Paul and deposition
testimony of Ms. Holloway, is enough to support denial of
class certification under Rule 23(b)(3) for the putative class
members listed in Exhibit C.

    Exhibit B lists putative class members whose claims are
based on faxes sent to 2,701 unique fax numbers. McKesson
asserts several different consent defenses against these
putative class members. First, McKesson asserts that some
       TRUE HEALTH CHIROPRACTIC V. MCKESSON                19

putative class members listed in Exhibit B gave consent by
“check[ing] a box during their software registration that
indicated their express permission to be sent faxes as a
preferred method of communication to receive promotional
information.” Second, McKesson asserts that some of them
gave consent by “complet[ing] a written consent form
whereby they further provided their express permission to
receive faxes.” Third, McKesson asserts that some of them
gave consent by “confirm[ing],” via phone, “that they would
like to continue to receive faxes and/or would like to change
their communication method preferences” during an
“outreach program to update contact information of certain
preexisting customers.”

     It is possible that some or all of the putative class
members in Exhibit B satisfy the predominance requirement.
For example, the putative class members against whom the
first defense would be asserted—those who “check[ed] a box
during their software registration”—may be indistinguishable
from those class members listed in Exhibit A who assertedly
gave consent during product registration. If so, their claims
would satisfy the predominance requirement of Rule 23(b)(3).
Further, the claims of class members who assertedly gave
consent by “complet[ing] a written consent form” may also
satisfy the predominance requirement. Given the somewhat
unclear state of the record, and given that the district court
has not had an opportunity to address class certification in
light of our intervening decision in Van Patten, we view these
and other issues related to Exhibit B as best addressed in the
first instance by the district court on remand.
20       TRUE HEALTH CHIROPRACTIC V. MCKESSON

                          Conclusion

     On the current record, we affirm in part, reverse in part,
and remand. We affirm the district court’s denial of class
certification with respect to a possible subclass of the putative
class members with the fifty-five unique fax numbers in
Exhibit C. We reverse the district court’s holding that the
other possible subclasses cannot satisfy the predominance
requirement of Rule 23(b)(3). We hold that the subclass of
putative class members with 9,223 unique fax numbers that
would be created by taking out of Exhibit A the putative class
members listed in Exhibits B and C would satisfy the
predominance requirement of Rule 23(b)(3). We remand for
a determination by the district court whether the claims and
defenses applicable to some or all of the class of putative
class members with 2,701 unique fax numbers listed in
Exhibit B would satisfy the predominance requirement of
Rule 23(b)(3). Finally, we remand to allow the district court
to address the requirements of Rule 23(a), which the court did
not reach in its earlier decision. We leave it to the district
court, in its discretion, to allow supplementation of the record
in light of Van Patten and this opinion.

  AFFIRMED in part, REVERSED in part, and
REMANDED.

     The parties shall bear their own costs.
