Court Opinion

ID: 2671191
Source: CourtListenerOpinion
Date Created: 2014-04-24 17:33:55.986404+00
Date Added: 2024-06-11T11:14:39.358805
License: Public Domain

FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

JUANITA STOCKWELL; MICHAEL                 No. 12-15070
LEWIS; VINCE NEESON; GUILLERMO
L. AMIGO; E. R. BALINTON;                    D.C. No.
NIKOLAUS BORTHNE; EDWARD                  4:08-cv-05180-
BROWNE; PETER BUSALACCHI;                      PJH
SILVIA DAVID; PHILIP FLECK;
SEVERO FLORES; GEORGE FOGARTY;
MALCOLM FONG; MARY GODFREY;                  OPINION
JASON HUI; JACKLYN M. JEHL;
RICHARD JUE; ROBERT LEUNG; PAUL
LOZADA; D.H. BUD MASSEY; BRUCE
MEADORS; THOMAS O’CONNOR;
SUSAN ROLOVICH; JESSIE
WASHINGTON; MICHAEL WELLS;
GARY CASTEL; BARTHOLOMEW
JOHNSON; MIKE BOLTE; JONES
JAMES,
               Plaintiffs-Appellants,

                 v.

CITY AND COUNTY OF SAN
FRANCISCO,
             Defendant-Appellee.

      Appeal from the United States District Court
         for the Northern District of California
      Phyllis J. Hamilton, District Judge, Presiding
2     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

                  Argued and Submitted
       September 10, 2013—San Francisco, California

                       Filed April 24, 2014

      Before: J. Clifford Wallace, Raymond C. Fisher,
           and Marsha S. Berzon, Circuit Judges.

                    Opinion by Judge Berzon

                           SUMMARY*

           Fed. R. Civ. P. 23(f) Class Certification

    The panel in an interlocutory appeal reversed the district
court’s denial for want of commonality of a request under
Fed. R. Civ. P. 23(f) for certification of a class composed of
certain San Francisco Police Department officers.

    The panel held that the district court abused its discretion
in denying class certification because of its legal error of
evaluating merits questions, rather than focusing on whether
the questions presented, whether meritorious or not, were
common to the members of the putative class. The panel held
that given the interlocutory nature of the appeal, and its
consequent limitation to class certification factors only, the
panel could not consider the merits questions, even as an
alternative ground for affirmance. The panel remanded to the
district court to consider in the first instance whether the

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO                3

putative class satisfied the strictures of Rule 23(b)(3), as well
as the other prerequisites for class certification.

                         COUNSEL

Michael S. Sorgen (argued), Andrea Adam Brott, and Ryan
L. Hicks, Law Offices of Michael S. Sorgen, San Francisco,
California; and Richard A. Hoyer, Hoyer and Associates, San
Francisco, California, for Plaintiffs-Appellants.

Christine Van Aken (argued), Deputy City Attorney, Dennis
J. Herrera, City Attorney, Elizabeth Salveson, Chief Labor
Attorney, and Jonathan C. Rolnick, Deputy City Attorney,
City of San Francisco, San Francisco, California, for
Defendant-Appellee.

                          OPINION

BERZON, Circuit Judge:

    Several San Francisco police officers (“the plaintiffs” or
“the officers”) over the age of forty performed well enough
on an examination in 1998 to qualify for consideration for
promotion to Assistant Inspector. They allege that a new
policy of the San Francisco Police Department (“SFPD”)
abandoning the examination as a basis for certain assignments
worked a disparate impact based on age. The plaintiffs
sought certification of a class composed of all SFPD officers
over forty who had qualified on the 1998 examination.

   The district court denied certification for want of
commonality. We permitted the officers to appeal the denial
4    STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

of class certification under Federal Rule of Civil Procedure
23(f), and now reverse, holding improper the district court’s
reliance on merits issues unrelated to the pertinent
commonality inquiry.

                               I.

    Nearly three and a half decades ago, the Civil Service
Commission of the City and County of San Francisco
(“City”) entered into a consent decree to settle allegations of
employment discrimination in the SFPD on the basis of race,
sex, and national origin, in violation of Title VII of the Civil
Rights Act of 1964, 42 U.S.C. § 2000e et seq.

    In late 1998, the district court terminated that consent
decree. By stipulation of the parties, however, the district
court retained jurisdiction over issues related to a recently
administered promotional examination — the Q-35 Assistant
Inspector examination for promotion to the Investigations
Bureau — which the parties agreed would be governed by the
terms of the consent decree. On the same day, the district
court issued an order outlining promotion procedures for
officers who had sat for the Q-35 Assistant Inspector
examination. That order required a minimum of 175
Assistant Inspector appointments from the list of police
officers who had passed the examination, arranged in order of
exam performance (“Q-35 List”). The first 110 promotions
were to be made in rank order of performance. Subsequent
appointments, the court ordered, “will be made from a sliding
band that will start at rank 111. The band width is 84 points.”
The district court authorized the City to review various
“secondary criteria” when making selections within that
sliding band. Between 1998 and 2006, the City selected 229
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO                5

police officers from the Q-35 List for promotion to Assistant
Inspector.

    In 2005, the Chief of Police announced a change in
promotion policy: To improve operational flexibility and
rationalize the promotional progression, the SFPD would no
longer promote Assistant Inspectors to the Investigations
Bureau from the Q-35 List. Instead, the SFPD would
administer a new Q-50 Sergeants examination and assign
some newly promoted Sergeants, selected on the basis of their
performance on the new exam, to the Investigations Bureau.
Those Sergeants assigned to the Investigations Bureau would
have duties previously assigned to Assistant Inspectors.

    The City administered the Q-50 Sergeants Examination
in 2006 and created a list of eligible officers (“Q-50 List”) the
following year. Soon thereafter, the SFPD began promoting
Sergeants from the recently compiled Q-50 List, many of
whom were given investigative duties. Assistant Chief
Morris Tabak agreed, in a deposition taken in this case, that
he knew of no reason “that those appointments could not have
been made from the Q-35 list[] that resulted from the 1998
exam.”

    The officers initially filed this action in late 2008,
alleging that SFPD’s decision to use the Q-50 list instead of
the Q-35 list for investigative assignments both constituted a
pattern or practice of discrimination and generated a disparate
impact on older officers in violation of the Age
Discrimination in Employment Act (“ADEA”), 29 U.S.C.
§§ 621–634. They also alleged parallel violations of
California’s Fair Employment and Housing Act (“FEHA”),
Cal. Gov’t Code §§ 12940–12951.
6       STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

    The officers subsequently sought certification of a class
under their FEHA disparate impact claim. The district court
denied the motion for certification, explaining that the
officers failed to satisfy the requirements of both Federal
Rules of Civil Procedure 23(a)(2) and 23(b)(3).

     After denial of certification, the officers filed a Second
Amended Complaint alleging only a disparate impact theory
of liability, again under both the ADEA and FEHA. Several
months later, the officers renewed their motion for class
certification of the FEHA claim,1 proposing as the class to be
certified SFPD “officers who were aged forty and older as of
each of the dates of the challenged appointments in 2007,
2008, and 2009 and who could have been appointed to
investigative positions had the City properly made
appointments from the Q-35 List.” The putative class defined
an officer “who could have been appointed,” as an officer
within the 84-point selection band at the time SFPD assigned
a sergeant to investigative work. The officers further
proposed the creation of separate subclasses for those who
could have been appointed at each date. Certification was
sought under Rule 23(b)(3). As the common question
required for certification, Fed. R. Civ. P. 23(a)(2), the officers
asserted a common question of fact: “[W]hether the City’s
employment practice of appointing Sergeants exclusively
from the Q-50 List to investigative positions traditionally
performed by Assistant Inspectors and refusing to make any

    1
     The officers also sought “conditional certification” of a collective
action under the ADEA on the ground that 29 U.S.C. § 216(b), which
governs collective actions under the ADEA, requires a lesser showing to
authorize aggregate litigation. For the purposes of this appeal, the officers
have forfeited that claim by failing to argue it in their briefs. See, e.g.,
Dream Games of Ariz., Inc. v. PC Onsite, 561 F.3d 983, 994–95 (9th Cir.
2009).
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO              7

of the appointments from the active Q-35 List, had a disparate
impact on qualified applicants for the investigative positions
who were aged forty or above at the time of those
appointments, in violation of FEHA.”

    The district court denied the renewed motion for class
certification for want of commonality. Having disposed of
the motion on that ground, the district court expressly
declined to rule on the officers’s argument that the putative
class satisfied the requirement of Rule 23(b)(3), which
requires both that common questions “predominate over any
questions affecting only individual members” of the class and
“that a class action is superior to other available methods for
fairly and efficiently adjudicating the controversy.”

    The officers timely sought permission to appeal under
Rule 23(f), which authorizes discretionary review of an
interlocutory order granting or denying class certification.
See Fed. R. Civ. P. 23(f); see also Chamberlan v. Ford Motor
Co., 402 F.3d 952, 959 (9th Cir. 2005) (per curiam)
(describing the standards we employ to guide our
discretionary authorization of appeals under Rule 23(f)). This
Court granted permission for the appeal, and the officers
timely perfected it. See Fed. R. App. P. 5(d).

                              II.

    Federal Rule of Civil Procedure 23(a)(2) conditions class
certification on demonstrating that members of the proposed
class share common “questions of law or fact.” Such
commonality is one of four “threshold requirements”
contained in Rule 23(a); the other three are numerosity,
8          STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

typicality, and adequacy of representation.2 See, e.g.,
Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 613 (1997).
Together, these requirements seek to “limit the class claims
to those fairly encompassed by the named plaintiff’s claims.”
Wal-Mart Stores, Inc. v. Dukes, 131 S. Ct. 2541, 2550 (2011)
(quoting Gen. Tel. Co. of Sw. v. Falcon, 457 U.S. 147, 156
(1982)) (internal quotation marks omitted).

    Wal-Mart instructed that, although Rule 23(a)(2) refers to
common “questions of law or fact” in the plural, “‘[e]ven a
single [common] question’ will do.” Id. at 2556 (alterations
in original) (quoting id. at 2566 n.9 (Ginsburg, J.,
dissenting)). We have since clarified “that Rule 23(a)(2)
requires . . . ‘a single significant question of law or fact.’”
Abdullah v. U.S. Sec. Assocs., Inc., 731 F.3d 952, 957 (9th
Cir. 2013) (emphasis in original) (quoting Mazza v. Am.
Honda Motor Co., 666 F.3d 581, 589 (9th Cir. 2012)).

    2
        The text of the subsection is as follows:

             (a) Prerequisites. One or more members of a class may
             sue or be sued as representative parties on behalf of all
             members only if:

             (1) the class is so numerous that joinder of all members
             is impracticable;

             (2) there are questions of law or fact common to the
             class;

             (3) the claims or defenses of the representative parties
             are typical of the claims or defenses of the class; and

             (4) the representative parties will fairly and adequately
             protect the interests of the class.

Fed. R. Civ. P. 23(a).
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO               9

    Rule 23(a)(2) is not “a mere pleading standard,” so
establishing commonality sometimes requires affirmative
evidence, which the courts must subject to “rigorous
analysis.” Wal-Mart, 131 S. Ct. at 2551 (quoting Falcon,
457 U.S. at 161). Such rigor often “will entail some overlap
with the merits of the plaintiff’s underlying claim.” Id.
While some evaluation of the merits frequently “cannot be
helped” in evaluating commonality, id., that likelihood of
overlap with the merits is “no license to engage in free-
ranging merits inquiries at the certification stage.” Amgen
Inc. v. Conn. Ret. Plans & Trust Funds, 133 S. Ct. 1184,
1194–95 (2013). Instead, as the Supreme Court clarified last
year, “[m]erits questions may be considered to the extent —
but only to the extent — that they are relevant to determining
whether the Rule 23 prerequisites for class certification are
satisfied.” Id. at 1195 (emphasis added). “[W]hether class
members could actually prevail on the merits of their claims”
is not a proper inquiry in determining the preliminary
question “whether common questions exist.” Ellis v. Costco
Wholesale Corp., 657 F.3d 970, 983 n.8 (9th Cir. 2011).

     Further, a common contention need not be one that “will
be answered, on the merits, in favor of the class.” Amgen,
133 S. Ct. at 1191. Instead, it only “must be of such a nature
that it is capable of classwide resolution — which means that
determination of its truth or falsity will resolve an issue that
is central to the validity of each one of the claims in one
stroke.” Wal-Mart, 131 S. Ct. at 2551 (emphases added).
“To hold otherwise would turn class certification into a mini-
trial” on the merits, Ellis, 657 F.3d at 983 n.8, when the
purpose of class certification is merely “to select the metho[d]
best suited to adjudication of the controversy fairly and
efficiently,” Amgen, 133 S. Ct. at 1191 (alteration in original)
(internal quotation marks omitted).
10   STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

     Amgen, published over a year after the district court
decision here, illustrates well the application of the principle
that demonstrating commonality does not require proof that
the putative class will prevail on whatever common questions
it identifies. In Amgen, a class alleged securities fraud under
§ 10(b) of the Securities Exchange Act of 1934, 48 Stat. 891,
as amended, 15 U.S.C. § 78j(b), and Securities and Exchange
Commission Rule 10b–5, 17 C.F.R. § 240.10b–5. 133 S. Ct.
at 1191. To succeed on the merits, plaintiffs alleging
securities fraud under Rule 10b–5 “must prove ‘(1) a material
misrepresentation or omission by the defendant; (2) scienter;
(3) a connection between the misrepresentation or omission
and the purchase or sale of a security; (4) reliance upon the
misrepresentation or omission; (5) economic loss; and
(6) loss causation.’” Id. at 1192 (quoting Matrixx Initiatives,
Inc. v. Siracusano, 131 S. Ct. 1309, 1317 (2011)) (internal
quotation marks omitted). The fraud-on-the-market doctrine
“permits certain Rule 10b–5 plaintiffs to invoke a rebuttable
presumption of reliance on material misrepresentations aired
to the general public,” when those misrepresentations concern
securities traded in an efficient market. Id. To invoke the
fraud-on-the-market presumption, “plaintiffs must
demonstrate that the alleged misrepresentations were publicly
known . . . , that the stock traded in an efficient market, . . .
that the relevant transaction took place ‘between the time the
misrepresentations were made and the time the truth was
revealed,’” Erica P. John Fund, Inc. v. Halliburton Co., 131
S. Ct. 2179, 2185 (2011) (quoting Basic Inc. v. Levinson,
485 U.S. 224, 248 n.27 (1988)), and that the
misrepresentations were material, Amgen, 133 S. Ct. at 1195.

    Amgen held that where a class of investors seeks to rely
on the fraud-on-the-market presumption, proof of materiality
is unnecessary to certify a class under Rule 23(b)(3). Id. at
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO              11

1191. The reasoning, in part, was that “[t]he alleged
misrepresentations and omissions, whether material or
immaterial, would be so equally for all investors composing
the class.” Id. at 1191. If the factfinder ultimately held those
representations immaterial, that determination would not
amount to “some fatal dissimilarity among class members
that would make use of the class-action device inefficient or
unfair. Instead, [it would generate] a fatal similarity —
failure of proof as to an element of the plaintiffs cause of
action.” Id. at 1197 (emphases added) (alteration omitted)
(quoting Richard A. Nagareda, Class Certification in the Age
of Aggregate Proof, 84 N.Y.U. L. Rev. 97, 107 (2009))
(internal quotation marks omitted). By its very nature, such
a similarity, whether fatal or not to the merits of the
materiality issue, is a common question. Although proof of
materiality was “an essential predicate of the fraud-on-the-
market theory,” id. at 1195, the court held it “properly
addressed at trial or in a ruling on a summary-judgment
motion,” id. at 1197.

    Notably, Amgen concerned satisfaction of Rule 23(b)(3),
which requires not merely a common question but also
“find[ing] that the questions of law or fact common to class
members predominate over any questions affecting only
individual members.” It held proof of a factor that would
ultimately be essential to success on the class’s claims not
merely unnecessary to demonstrate commonality, but also
unnecessary to demonstrate that such commonality
predominates.      Rule 23(b)(3) imposes a “far more
demanding” standard than 23(a)(2). Amchem, 521 U.S. at
624. It was the less demanding standard of Rule 23(a)(2) that
was the basis of the district court’s denial of certification
here.
12   STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

    The principle that courts must consider merits issues only
as necessary to determine a pertinent Rule 23 factor, and not
otherwise, has special force at the appellate level where, as
here, we review a class certification determination under Rule
23(f). Under Rule 23(f), the limitation on consideration of
the merits to the relevant class certification questions is of
jurisdictional significance. Rule 23(f) permits discretionary,
interlocutory appeals “from an order granting or denying
class-action certification.”        Fed. R. Civ. P. 23(f).
Interlocutory appeals are, of course, “the exception rather
than the rule.” Chamberlan, 402 F.3d at 959. Absent Rule
23(f) or some other applicable exception, our jurisdiction
would be constrained by “‘the general rule that a party is
entitled to a single appeal, to be deferred until final judgment
has been entered.’” Mohawk Indus., Inc. v. Carpenter,
558 U.S. 100, 106 (2009) (quoting Digital Equip. Corp. v.
Desktop Direct, Inc., 511 U.S. 863, 868 (1994)); see also
28 U.S.C. § 1291. As the exception to the final judgment rule
created by Rule 23(f) applies only to class certification
decisions, merits inquiries unrelated to certification exceed
our limited Rule 23(f) jurisdiction, as well as the needs of
Rule 23(a)–(b). In contrast, were this an appeal from a final
judgment after a class was certified (or not certified) and the
merits then determined, we would have the option of
addressing the merits and, if we decided to hold against the
plaintiffs, not addressing the class certification question. We
must police the bounds of our jurisdiction vigorously here as
elsewhere, see, e.g., Crowley v. Bannister, 734 F.3d 967, 974
(9th Cir. 2013), and so may not ourselves venture into merits
issues unnecessary to the Rule 23 issue before us.
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO                13

                              III.

     With that background, we reach the only question
properly before us — whether the district court’s denial of the
officers’s motion for class certification was an abuse of
discretion. See Ellis, 657 F.3d at 980. An “error of law[,]
. . . . ‘reliance on an improper factor, . . . omission of a
substantial factor, or . . . a clear error of judgment in weighing
the correct mix of factors’” qualifies as an abuse of
discretion. Bateman v. Am. Multi-Cinema, Inc., 623 F.3d
708, 712 (9th Cir. 2010) (quoting In re Wells Fargo Mortg.
Overtime Pay Litig., 571 F.3d 953, 957 (9th Cir. 2009)). We
conclude that the district court erred in denying class
certification because of its legal error of evaluating merits
questions, rather than focusing on whether the questions
presented, whether meritorious or not, were common to the
members of the putative class. By doing so, the district court
made an error of law and relied on improper factors, thereby
abusing its discretion.

    To assess whether the putative class members share a
common question, the answer to which “will resolve an issue
that is central to the validity of each one of the [class
members’s] claims,” we must identify the elements of the
class members’s case-in-chief. Wal-Mart, 131 S. Ct. at 2551.
The requisite prima facie case for a disparate-impact age
discrimination claim under California’s FEHA is parallel to
that under the ADEA. See Katz v. Regents of the Univ. of
Cal., 229 F.3d 831, 835 (9th Cir. 2000); see also Clark v.
Claremont Univ. Ctr., 6 Cal. App. 4th 639, 666 (1992).
Under both statutes, “a plaintiff must demonstrate ‘(1) the
occurrence of certain outwardly neutral employment
practices, and (2) a significantly adverse or disproportionate
impact on persons of a particular [age] produced by the
14    STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

employer’s facially neutral acts or practices.’” Katz, 229 F.3d
at 835 (alteration in original) (quoting Palmer v. United
States, 794 F.2d 534, 538 (9th Cir. 1986)). This formulation
requires a plaintiff to “‘isolat[e] and identify[] the specific
employment practices that are allegedly responsible for any
observed statistical disparities.’” Smith v. City of Jackson,
544 U.S. 228, 241 (2005) (emphasis in original) (quoting
Wards Cove Packing Co. v. Atonio, 490 U.S. 642, 656
(1989)). The plaintiff must also demonstrate a causal
connection between those specific employment practices and
the asserted impact on those of a particular age. See, e.g.,
Lewis v. City of Chicago, 560 U.S. 205, 212 (2010); Katz,
229 F.3d at 836.3

    Here, the officers have identified a single, well-
enunciated, uniform policy that, allegedly, generated all the
disparate impact of which they complain: the SFPD’s
decision to make investigative assignments using the Q-50
List instead of the Q-35 List. Each member of the putative

 3
   The ADEA codifies “five affirmative defenses” at 29 U.S.C. § 623(f).
Meacham v. Knolls Atomic Power Lab., 554 U.S. 84, 91 (2008) (quoting
Trans World Airlines, Inc. v. Thurston, 469 U.S. 111, 122 (1985))
(internal quotation marks omitted). An employer is not liable, for
example, for otherwise-prohibited actions “where age is a bona fide
occupational qualification reasonably necessary to the normal operation
of the particular business, or where the differentiation is based on
reasonable factors other than age . . . .” 29 U.S.C. § 623(f)(1); see also
29 U.S.C. § 623(f) (listing other defenses). The FEHA also contains
affirmative defenses for, inter alia, “bona fide occupational
qualification[s]” and employment actions based on business necessity.
Cal. Gov’t Code § 12940; Cal. Code Regs. tit. 2, § 11010.

     The availability of such defenses, however, is not pertinent to the
commonality question, as long as there is a common question as to the
officers’s prima facie case of disparate impact age discrimination.
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO              15

class was on the Q-35 List. Each suffered the effects of its
elimination, whatever those were.

    “Identifying a specific practice is not a trivial burden” in
age discrimination cases alleging disparate impact.
Meacham, 554 U.S. at 101. Indeed, the first Supreme Court
case to recognize the viability of a disparate-impact theory
under the ADEA rejected the claim on the merits for “failure
to identify the specific practice being challenged,” among
other shortcomings. Smith, 544 U.S. at 241. Requiring
plaintiffs to name a specific employment practice “has bite,”
Meacham, 554 U.S. at 100, both on the merits and for
purposes of determining whether there is a common question
in a disparate impact case. Here, the putative class is
challenging a single employment practice: making
investigative assignments from the Q-50 List instead of the
Q-35 List.

    Once a specific practice is identified in a disparate impact
case, the next — although not the only — question becomes
whether that practice had a disproportionate adverse impact
on otherwise eligible officers over forty. “Generally
disparate impact analysis is used in a class action, but it may
also form the basis of an individual claim.” Bacon v. Honda
of Am. Mfg., Inc., 370 F.3d 565, 576 (6th Cir. 2004); see also
Watson v. Fort Worth Bank & Trust, 487 U.S. 977, 983
(1988) (addressing an individual disparate impact claim);
Pottenger v. Potlatch Corp., 329 F.3d 740, 749–50 (9th Cir.
2003) (same). In whatever procedural guise a disparate
impact claim appears, the party asserting it must demonstrate
a statistical disparity affecting members of the protected
16       STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

group. Absent such a group-based disparity, the claim fails,
whether it is articulated by an individual or a class.4

     The officers produced a statistical study purportedly
showing a disparate impact. The district court, and the City,
critiqued that study as inadequate for — among other reasons
— failing to conduct a regression analysis to take account of
alternative explanations, unrelated to age, for any statistical
imbalance. But whatever the failings of the class’s statistical
analysis, they affect every class member’s claims uniformly,
just as the materiality issue in Amgen affected every class
member uniformly. Each member of the putative class
suffered the effects of eliminating the Q-35 List.5 If those

 4
    This feature of disparate impact analysis distinguishes it sharply from
the theory of disparate treatment. Disparate impact analysis addresses
itself “to the consequences of employment practices, not simply the
motivation.” Griggs v. Duke Power Co., 401 U.S. 424, 432 (1971). Such
discriminatory consequences are perceptible only in the aggregate, which
is why we require statistical evidence. By contrast, the crux of a disparate
treatment case is the subjective motivation for an adverse employment
decision. Although statistical evidence can support a disparate treatment
claim, as in the pattern-or-practice cases of the type addressed by Wal-
Mart, such evidence is only “probative of motive,” used for the purpose
of “creat[ing] an inference of discriminatory intent with respect to the
individual employment decision at issue.” Obrey v. Johnson, 400 F.3d
691, 694 (9th Cir. 2005) (emphasis added) (quoting Diaz v. Am. Tel. &
Tel., 752 F.3d 1356, 1363 (9th Cir. 1985)).
     5
     Contrary to the City’s argument, that is true with respect to those
members who took and succeeded on the new Q-50 examination, as they
lost the same promotional opportunity as their peers, regardless of whether
their subsequent actions entitled them to similar — but not identical —
promotional opportunities. Whether those individuals will be precluded
from obtaining any relief because of their promotions based on the Q-50
examination is a separate question, as is the impact of that question on the
Rule 23(b)(3) analysis to be conducted on remand, see infra Part IV.
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO              17

effects amount to a disparate impact on account of age, it will
be so for all class members or for none; their claims rise and
fall together.

    That the City primarily relies on Katz for its contrary
argument reveals the fallacy of its position. Katz considered
not class certification but an already certified class’s appeal
of an adverse judgment on the merits. 229 F.3d at 833.

    In Katz, a class of laboratory employees claimed the
decision to offer certain early retirement incentives to
participants in the University of California Retirement Plan,
whose average age was 55, and not to participants in the
Public Employee Retirement System, whose average age was
60, generated a disparate impact on the basis of age. Id. at
833–34. We affirmed the district court’s judgment as a
matter of law against the plaintiffs, reasoning they had “failed
to demonstrate causation,” insofar as their statistical evidence
was “insufficient to raise an inference that the disparate
impact fell upon employees by virtue of their membership in
a protected age group.” Id. at 836. The failure to produce
statistics sufficient to demonstrate a causal relationship
between employee age and employer practice defeated the
claims of the entire class.

    The same will be true here — the statistical showing of
disparate impact due to the challenged policy will either
succeed as to the class as a whole or, as the City argues, fail
— again, with respect to the class as a whole. In highlighting
the questions of statistical proof of disparate impact and
causation, the City has strengthened, not weakened, the case
for certification, as it has identified a common question, the
resolution of which will uniformly affect all members of the
class. And whether there is a disparate impact on the putative
18   STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

class, to be established through statistical proof, is “a single
significant question of . . . fact,” Abdullah, 731 F.3d at 957
(emphasis in original) (internal quotation marks omitted), the
resolution of which is “central to the validity” of each of the
class members’s claims, Wal-Mart, 131 S. Ct. at 2551.

     The City offers various reasons the putative class, or
various members of it, may not prevail, including: the
decision not to use the Q-35 List affected all officers on the
list equally, without regard to age; all the officers on the Q-35
List could have taken the Q-50 examination, so there was no
detrimental impact on them from the policy change; there
were no appointments of any Assistant Inspectors from 2007
through 2009, so the Q-35 List was inapplicable during that
period; and many of the class members would not have been
promoted even if the Q-35 List were used, as there would not
have been enough positions for all of them. Any and all of
these considerations may prove pertinent to the merits of the
case, and possibly to whether common issues predominate
under Rule 23(b)(3). But they do not eliminate the significant
common question we have identified, however that question
is ultimately answered and whether or not other, individual
questions are later determined to predominate.

    In short, the officers are all challenging a single policy
they contend has adversely affected them. The question
whether the policy has an impermissible disparate impact on
the basis of age necessarily has a single answer. To so
recognize is in no way to approve of the statistical showing
the officers have made as adequate to make out their merits
case. Nor does identifying a common question sufficient for
Rule 23(a)(2) purposes entail any disagreement with the
City’s contention that proper statistical analysis would negate
any disparate impact traceable to age — or, for that matter, to
     STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO             19

prejudge any other argument or defense the City may offer.
The defects the City has identified may well exist, but they go
to the merits of this case, or to the predominance question,
see infra Part IV. Given the interlocutory nature of this
appeal, and its consequent limitation to class certification
factors only, we may not consider the merits questions, even
as an alternative ground for affirmance.

                             IV.

    Having disposed of the officers’s certification motion for
want of commonality, the district court expressly declined to
evaluate the putative class’s argument that it satisfied the
predominance and superiority requirements of Rule 23(b)(3).
The City now contends that “individual questions will
predominate with respect to [the officers’s] claims including:
(a) whether an officer took the 2006 Sergeants exam or not;
(b) comparisons of individual rank on and between the 1998
Assistant Inspector list and the 2007 Sergeant list; (c) the
relative qualifications of each officer on the list; and,
(d) other factors affecting an assignment to the Investigations
Bureau.” The City may or may not be correct. But those
questions, as they affect predominance, have been
inadequately briefed here. They have no effect on
commonality, because there is a single, logically prior,
common question: whether the cancellation of the Q-35 List
generated a disparate impact on older officers.

    The effect of the questions the City raises on the
predominance inquiry are best addressed by the district court,
which is “‘in the best position to consider the most fair and
efficient procedure for conducting any given litigation,’
Doninger v. Pac. N.W. Bell, Inc., 564 F.2d 1304, 1309 (9th
Cir. 1977), and so must be given ‘wide discretion’ to evaluate
20   STOCKWELL V. CITY & CNTY. OF SAN FRANCISCO

superiority [under Rule 23(b)(3)], Lerwill v. Inflight Motion
Pictures, Inc., 582 F.2d 507, 512 (9th Cir. 1978).” Bateman,
623 F.3d at 712 (citation formatting in original). We thus
REMAND to the district court to consider in the first instance
whether the putative class satisfies the strictures of Rule
23(b)(3), as well as the other prerequisites for class
certification.

                             V.

    We REVERSE the district court’s denial of certification
for want of commonality. That determination was an abuse
of discretion, as it disregarded the existence of common
questions of law and fact and impermissibly addressed the
merits of the class’s claims.

     REVERSED and REMANDED.