(Slip Opinion)              OCTOBER TERM, 2015                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

       TYSON FOODS, INC. v. BOUAPHAKEO ET AL.,
  INDIVIDUALLY AND ON BEHALF OF ALL OTHERS SIMILARLY
                       SITUATED

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                 THE EIGHTH CIRCUIT

  No. 14–1146.      Argued November 10, 2015—Decided March 22, 2016
Respondents, employees of petitioner Tyson Foods, work in the kill, cut,
  and retrim departments of a pork processing plant in Iowa. Re-
  spondents’ work requires them to wear protective gear, but the exact
  composition of the gear depends on the tasks a worker performs on a
  given day. Petitioner compensated some, but not all, employees for
  this donning and doffing, and did not record the time each employee
  spent on those activities. Respondents filed suit, alleging that the
  donning and doffing were integral and indispensable to their hazard-
  ous work and that petitioner’s policy not to pay for those activities
  denied them overtime compensation required by the Fair Labor
  Standards Act of 1938 (FLSA). Respondents also raised a claim un-
  der an Iowa wage law. They sought certification of their state claims
  as a class action under Federal Rule of Civil Procedure 23 and certifi-
  cation of their FLSA claims as a “collective action.” See 29 U. S. C.
  §216. Petitioner objected to certification of both classes, arguing that,
  because of the variance in protective gear each employee wore, the
  employees’ claims were not sufficiently similar to be resolved on a
  classwide basis. The District Court concluded that common ques-
  tions, such as whether donning and doffing protective gear was com-
  pensable under the FLSA, were susceptible to classwide resolution
  even if not all of the workers wore the same gear. To recover for a
  violation of the FLSA’s overtime provision, the employees had to
  show that they each worked more than 40 hours a week, inclusive of
  the time spent donning and doffing. Because petitioner failed to keep
  records of this time, the employees primarily relied on a study per-
  formed by an industrial relations expert, Dr. Kenneth Mericle. Mer-
2              TYSON FOODS, INC. v. BOUAPHAKEO

                               Syllabus

 icle conducted videotaped observations analyzing how long various
 donning and doffing activities took, and then averaged the time taken
 to produce an estimate of 18 minutes a day for the cut and retrim de-
 partments and 21.25 minutes for the kill department. These esti-
 mates were then added to the timesheets of each employee to ascer-
 tain which class members worked more than 40 hours a week and the
 value of classwide recovery. Petitioner argued that the varying
 amounts of time it took employees to don and doff different protective
 gear made reliance on Mericle’s sample improper, and that its use
 would lead to recovery for individuals who, in fact, had not worked
 the requisite 40 hours. The jury awarded the class about $2.9 million
 in unpaid wages. The award has not yet been disbursed to individual
 employees. The Eighth Circuit affirmed the judgment and the
 award.
Held: The District Court did not err in certifying and maintaining the
 class. Pp. 8–17.
    (a) Before certifying a class under Rule 23(b)(3), a district court
 must find that “questions of law or fact common to class members
 predominate over any questions affecting only individual members.”
 The parties agree that the most significant question common to the
 class is whether donning and doffing protective gear is compensable
 under the FLSA. Petitioner claims, however, that individual inquir-
 ies into the time each worker spent donning and doffing predominate
 over this common question. Respondents argue that individual in-
 quiries are unnecessary because it can be assumed each employee
 donned and doffed for the same average time observed in Mericle’s
 sample.
    Whether and when statistical evidence such as Mericle’s sample
 can be used to establish classwide liability depends on the purpose
 for which the evidence is being introduced and on “the elements of
 the underlying cause of action,” Erica P. John Fund, Inc. v. Hallibur-
 ton Co., 563 U.S. 804, 809. Because a representative sample may be
 the only feasible way to establish liability, it cannot be deemed im-
 proper merely because the claim is brought on behalf of a class. Re-
 spondents can show that Mericle’s sample is a permissible means of
 establishing hours worked in a class action by showing that each
 class member could have relied on that sample to establish liability
 had each brought an individual action.
    Anderson v. Mt. Clemens Pottery Co., 328 U. S. 680, shows why
 Mericle’s sample was permissible in the circumstances of this case.
 There, where an employer violated its statutory duty to keep proper
 records, the Court concluded the employees could meet their burden
 by proving that they in fact “performed work for which [they were]
 improperly compensated and . . . produc[ing] sufficient evidence to
                     Cite as: 577 U. S. ____ (2016)                    3

                                Syllabus

  show the amount and extent of that work as a matter of just and rea-
  sonable inference.” Id., at 687. Here, similarly, respondents sought
  to introduce a representative sample to fill an evidentiary gap creat-
  ed by the employer’s failure to keep adequate records. Had the em-
  ployees proceeded with individual lawsuits, each employee likely
  would have had to introduce Mericle’s study to prove the hours he or
  she worked. The representative evidence was a permissible means of
  showing individual hours worked.
    This holding is in accord with Wal-Mart Stores, Inc. v. Dukes, 564
  U. S. 338, where the underlying question was, as here, whether the
  sample at issue could have been used to establish liability in an indi-
  vidual action. There, the employees were not similarly situated, so
  none of them could have prevailed in an individual suit by relying on
  depositions detailing the ways in which other employees were dis-
  criminated against by their particular store managers. In contrast,
  the employees here, who worked in the same facility, did similar
  work, and were paid under the same policy, could have introduced
  Mericle’s study in a series of individual suits.
    This case presents no occasion for adoption of broad and categorical
  rules governing the use of representative and statistical evidence in
  class actions. Rather, the ability to use a representative sample to
  establish classwide liability will depend on the purpose for which the
  sample is being introduced and on the underlying cause of action. In
  FLSA actions, inferring the hours an employee has worked from a
  study such as Mericle’s has been permitted by the Court so long as
  the study is otherwise admissible. Mt. Clemens, supra, at 687.
  Pp. 8–15.
    (b) Petitioner contends that respondents are required to demon-
  strate that uninjured class members will not recover damages here.
  That question is not yet fairly presented by this case, because the
  damages award has not yet been disbursed and the record does not
  indicate how it will be disbursed. Petitioner may raise a challenge to
  the allocation method when the case returns to the District Court for
  disbursal of the award. Pp. 15–17.
765 F. 3d 791, affirmed and remanded.

   KENNEDY, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and GINSBURG, BREYER, SOTOMAYOR, and KAGAN, JJ., joined.
ROBERTS, C. J., filed a concurring opinion, in which ALITO, J., joined as
to Part II. THOMAS, J., filed a dissenting opinion, in which ALITO, J.,
joined.
                       Cite as: 577 U. S. ____ (2016)                              1

                            Opinion of the Court

    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash-
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                                  No. 14–1146
                                  _________________


     TYSON FOODS, INC., PETITIONER v. PEG
  BOUAPHAKEO, ET AL., INDIVIDUALLY AND ON BEHALF
              OF ALL OTHERS SIMILARLY SITUATED

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
           APPEALS FOR THE EIGHTH CIRCUIT
                               [March 22, 2016]

  JUSTICE KENNEDY delivered the opinion of the Court.
  Following a jury trial, a class of employees recovered
$2.9 million in compensatory damages from their employer
for a violation of the Fair Labor Standards Act of 1938
(FLSA), 52 Stat. 1060, as amended, 29 U. S. C. §201 et seq.
The employees’ primary grievance was that they did not
receive statutorily mandated overtime pay for time spent
donning and doffing protective equipment.
  The employer seeks to reverse the judgment. It makes
two arguments. Both relate to whether it was proper to
permit the employees to pursue their claims as a class.
First, the employer argues the class should not have been
certified because the primary method of proving injury
assumed each employee spent the same time donning and
doffing protective gear, even though differences in the
composition of that gear may have meant that, in fact,
employees took different amounts of time to don and doff.
Second, the employer argues certification was improper
because the damages awarded to the class may be distrib-
uted to some persons who did not work any uncompen-
2           TYSON FOODS, INC. v. BOUAPHAKEO

                     Opinion of the Court

sated overtime.
   The Court of Appeals for the Eighth Circuit concluded
there was no error in the District Court’s decision to cer-
tify and maintain the class. This Court granted certiorari.
576 U. S. ___ (2015).
                              I
  Respondents are employees at petitioner Tyson Foods’
pork processing plant in Storm Lake, Iowa. They work in
the plant’s kill, cut, and retrim departments, where hogs
are slaughtered, trimmed, and prepared for shipment.
Grueling and dangerous, the work requires employees to
wear certain protective gear. The exact composition of the
gear depends on the tasks a worker performs on a given
day.
  Until 1998, employees at the plant were paid under a
system called “gang-time.” This compensated them only
for time spent at their workstations, not for the time
required to put on and take off their protective gear. In
response to a federal-court injunction, and a Department
of Labor suit to enforce that injunction, Tyson in 1998
began to pay all its employees for an additional four
minutes a day for what it called “K-code time.” The
4-minute period was the amount of time Tyson estimated
employees needed to don and doff their gear. In 2007,
Tyson stopped paying K-code time uniformly to all em-
ployees. Instead, it compensated some employees for
between four and eight minutes but paid others nothing
beyond their gang-time wages. At no point did Tyson
record the time each employee spent donning and doffing.
  Unsatisfied by these changes, respondents filed suit in
the United States District Court for the Northern District
of Iowa, alleging violations of the FLSA. The FLSA re-
quires that a covered employee who works more than 40
hours a week receive compensation for excess time worked
“at a rate not less than one and one-half times the regular
                 Cite as: 577 U. S. ____ (2016)            3

                     Opinion of the Court

rate at which he is employed.” 29 U. S. C. §207(a). In
1947, nine years after the FLSA was first enacted, Con-
gress passed the Portal-to-Portal Act, which clarified that
compensable work does not include time spent walking to
and from the employee’s workstation or other “preliminary
or postliminary activities.” §254(d). The FLSA, however,
still requires employers to pay employees for activities
“integral and indispensable” to their regular work, even if
those activities do not occur at the employee’s workstation.
Steiner v. Mitchell, 350 U. S. 247, 249, 255 (1956). The
FLSA also requires an employer to “make, keep, and
preserve . . . records of the persons employed by him and
of the wages, hours, and other conditions and practices of
employment.” §211(c).
   In their complaint, respondents alleged that donning
and doffing protective gear were integral and indispensa-
ble to their hazardous work and that petitioner’s policy not
to pay for those activities denied them overtime compensa-
tion required by the FLSA. Respondents also raised a
claim under the Iowa Wage Payment Collection Law. This
statute provides for recovery under state law when an
employer fails to pay its employees “all wages due,” which
includes FLSA-mandated overtime. Iowa Code §91A.3
(2013); cf. Anthony v. State, 632 N. W. 2d 897, 901–902
(Iowa 2001).
   Respondents sought certification of their Iowa law
claims as a class action under Rule 23 of the Federal Rules
of Civil Procedure. Rule 23 permits one or more individ-
uals to sue as “representative parties on behalf of all mem-
bers” of a class if certain preconditions are met. Fed. Rule
Civ. Proc. 23(a). Respondents also sought certification of
their federal claims as a “collective action” under 29
U. S. C. §216. Section 216 is a provision of the FLSA that
permits employees to sue on behalf of “themselves and
other employees similarly situated.” §216(b).
   Tyson objected to the certification of both classes on the
4           TYSON FOODS, INC. v. BOUAPHAKEO

                     Opinion of the Court

same ground. It contended that, because of the variance
in protective gear each employee wore, the employees’
claims were not sufficiently similar to be resolved on a
classwide basis. The District Court rejected that position.
It concluded there were common questions susceptible to
classwide resolution, such as “whether the donning and
doffing of [protective gear] is considered work under the
FLSA, whether such work is integral and [in]dispensable,
and whether any compensable work is de minim[i]s.” 564
F. Supp. 2d 870, 899 (ND Iowa 2008). The District Court
acknowledged that the workers did not all wear the same
protective gear, but found that “when the putative plain-
tiffs are limited to those that are paid via a gang time
system, there are far more factual similarities than dis-
similarities.” Id., at 899–900. As a result, the District
Court certified the following classes:
       “All current and former employees of Tyson’s Storm
    Lake, Iowa, processing facility who have been em-
    ployed at any time from February 7, 2004 [in the case
    of the FLSA collective action and February 7, 2005, in
    the case of the state-law class action], to the present,
    and who are or were paid under a ‘gang time’ compen-
    sation system in the Kill, Cut, or Retrim depart-
    ments.” Id., at 901.
  The only difference in definition between the classes
was the date at which the class period began. The size of
the class certified under Rule 23, however, was larger
than that certified under §216. This is because, while a
class under Rule 23 includes all unnamed members who
fall within the class definition, the “sole consequence of
conditional certification [under §216] is the sending of
court-approved written notice to employees . . . who in
turn become parties to a collective action only by filing
written consent with the court.” Genesis HealthCare Corp.
v. Symczyk, 569 U. S. ___, ___ (2013) (slip op., at 8). A
                 Cite as: 577 U. S. ____ (2016)          5

                     Opinion of the Court

total of 444 employees joined the collective action, while
the Rule 23 class contained 3,344 members.
  The case proceeded to trial before a jury. The parties
stipulated that the employees were entitled to be paid for
donning and doffing of certain equipment worn to protect
from knife cuts. The jury was left to determine whether
the time spent donning and doffing other protective
equipment was compensable; whether Tyson was required
to pay for donning and doffing during meal breaks; and
the total amount of time spent on work that was not com-
pensated under Tyson’s gang-time system.
  Since the employees’ claims relate only to overtime, each
employee had to show he or she worked more than 40
hours a week, inclusive of time spent donning and doffing,
in order to recover. As a result of Tyson’s failure to keep
records of donning and doffing time, however, the employ-
ees were forced to rely on what the parties describe as
“representative evidence.” This evidence included employee
testimony, video recordings of donning and doffing at
the plant, and, most important, a study performed by an
industrial relations expert, Dr. Kenneth Mericle. Mericle
conducted 744 videotaped observations and analyzed how
long various donning and doffing activities took. He then
averaged the time taken in the observations to produce an
estimate of 18 minutes a day for the cut and retrim de-
partments and 21.25 minutes for the kill department.
  Although it had not kept records for time spent donning
and doffing, Tyson had information regarding each em-
ployee’s gang-time and K-code time. Using this data, the
employees’ other expert, Dr. Liesl Fox, was able to esti-
mate the amount of uncompensated work each employee
did by adding Mericle’s estimated average donning and
doffing time to the gang-time each employee worked and
then subtracting any K-code time. For example, if an
employee in the kill department had worked 39.125 hours
of gang-time in a 6-day workweek and had been paid an
6            TYSON FOODS, INC. v. BOUAPHAKEO

                      Opinion of the Court

hour of K-code time, the estimated number of compensable
hours the employee worked would be: 39.125 (individual
number of gang-time hours worked) + 2.125 (the average
donning and doffing hours for a 6-day week, based on
Mericle’s estimated average of 21.25 minutes a day) – 1
(K-code hours) = 40.25. That would mean the employee
was being undercompensated by a quarter of an hour of
overtime a week, in violation of the FLSA. On the other
hand, if the employee’s records showed only 38 hours of
gang-time and an hour of K-code time, the calculation
would be: 38 + 2.125 – 1 = 39.125. Having worked less than
40 hours, that employee would not be entitled to overtime
pay and would not have proved an FLSA violation.
  Using this methodology, Fox stated that 212 employees
did not meet the 40-hour threshold and could not recover.
The remaining class members, Fox maintained, had po-
tentially been undercompensated to some degree.
  Respondents proposed to bifurcate proceedings. They
requested that, first, a trial be conducted on the questions
whether time spent in donning and doffing was compensa-
ble work under the FLSA and how long those activities
took to perform on average; and, second, that Fox’s meth-
odology be used to determine which employees suffered an
FLSA violation and how much each was entitled to recover.
Petitioner insisted upon a single proceeding in which
damages would be calculated in the aggregate and by the
jury. The District Court submitted both issues of liability
and damages to the jury.
  Petitioner did not move for a hearing regarding the
statistical validity of respondents’ studies under Daubert
v. Merrell Dow Pharmaceuticals, Inc., 509 U. S. 579
(1993), nor did it attempt to discredit the evidence with
testimony from a rebuttal expert. Instead, as it had done
in its opposition to class certification, petitioner argued to
the jury that the varying amounts of time it took employ-
ees to don and doff different protective equipment made
                 Cite as: 577 U. S. ____ (2016)            7

                     Opinion of the Court

the lawsuit too speculative for classwide recovery. Peti-
tioner also argued that Mericle’s study overstated the
average donning and doffing time. The jury was in-
structed that nontestifying members of the class could
only recover if the evidence established they “suffered the
same harm as a result of the same unlawful decision or
policy.” App. 471–472.
   Fox’s calculations supported an aggregate award of
approximately $6.7 million in unpaid wages. The jury
returned a special verdict finding that time spent in don-
ning and doffing protective gear at the beginning and end
of the day was compensable work but that time during
meal breaks was not. The jury more than halved the
damages recommended by Fox. It awarded the class about
$2.9 million in unpaid wages. That damages award has
not yet been disbursed to the individual employees.
   Tyson moved to set aside the jury verdict, arguing,
among other things, that, in light of the variation in don-
ning and doffing time, the classes should not have been
certified. The District Court denied Tyson’s motion, and
the Court of Appeals for the Eighth Circuit affirmed the
judgment and the award.
   The Court of Appeals recognized that a verdict for the
employees “require[d] inference” from their representative
proof, but it held that “this inference is allowable under
Anderson v. Mt. Clemens Pottery Co., 328 U. S. 680, 686–
688 (1946).” 765 F. 3d 791, 797 (2014). The Court of
Appeals rejected petitioner’s challenge to the sufficiency of
the evidence for similar reasons, holding that, under the
facts of this case, the jury could have drawn “a ‘reasonable
inference’ of class-wide liability.” Id., at 799 (quoting
Anderson v. Mt. Clemens Pottery Co., 328 U. S. 680, 687
(1946)). Judge Beam dissented, stating that, in his view,
the class should not have been certified.
   For the reasons that follow, this Court now affirms.
8            TYSON FOODS, INC. v. BOUAPHAKEO

                      Opinion of the Court

                              II
   Petitioner challenges the class certification of the state-
law claims and the certification of the FLSA collective
action. The parties do not dispute that the standard for
certifying a collective action under the FLSA is no more
stringent than the standard for certifying a class under
the Federal Rules of Civil Procedure. This opinion as-
sumes, without deciding, that this is correct. For purposes
of this case then, if certification of respondents’ class
action under the Federal Rules was proper, certification of
the collective action was proper as well.
   Furthermore, as noted above, Iowa’s Wage Payment
Collection Law was used in this litigation as a state-law
mechanism for recovery of FLSA-mandated overtime pay.
The parties do not dispute that, in order to prove a viola-
tion of the Iowa statute, the employees had to do no more
than demonstrate a violation of the FLSA. In this opinion,
then, no distinction is made between the requirements for
the class action raising the state-law claims and the collec-
tive action raising the federal claims.
                              A
  Federal Rule of Civil Procedure 23(b)(3) requires that,
before a class is certified under that subsection, a district
court must find that “questions of law or fact common to
class members predominate over any questions affecting
only individual members.” The “predominance inquiry
tests whether proposed classes are sufficiently cohesive to
warrant adjudication by representation.” Amchem Prod-
ucts, Inc. v. Windsor, 521 U. S. 591, 623 (1997). This calls
upon courts to give careful scrutiny to the relation be-
tween common and individual questions in a case. An
individual question is one where “members of a proposed
class will need to present evidence that varies from mem-
ber to member,” while a common question is one where
“the same evidence will suffice for each member to make a
                 Cite as: 577 U. S. ____ (2016)          9

                     Opinion of the Court

prima facie showing [or] the issue is susceptible to gener-
alized, class-wide proof.” 2 W. Rubenstein, Newberg on
Class Actions §4:50, pp. 196–197 (5th ed. 2012) (internal
quotation marks omitted). The predominance inquiry
“asks whether the common, aggregation-enabling, issues
in the case are more prevalent or important than the non-
common, aggregation-defeating, individual issues.” Id.,
§4:49, at 195–196. When “one or more of the central is-
sues 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 damages or some
affirmative defenses peculiar to some individual class
members.” 7AA C. Wright, A. Miller, & M. Kane, Federal
Practice and Procedure §1778, pp. 123–124 (3d ed. 2005)
(footnotes omitted).
   Here, the parties do not dispute that there are im-
portant questions common to all class members, the most
significant of which is whether time spent donning and
doffing the required protective gear is compensable work
under the FLSA. Cf. IBP, Inc. v. Alvarez, 546 U. S. 21
(2005) (holding that time spent walking between the
locker room and the production area after donning protec-
tive gear is compensable work under the FLSA). To be
entitled to recovery, however, each employee must prove
that the amount of time spent donning and doffing, when
added to his or her regular hours, amounted to more than
40 hours in a given week. Petitioner argues that these
necessarily person-specific inquiries into individual work
time predominate over the common questions raised by
respondents’ claims, making class certification improper.
   Respondents counter that these individual inquiries are
unnecessary because it can be assumed each employee
donned and doffed for the same average time observed in
Mericle’s sample. Whether this inference is permissible
becomes the central dispute in this case. Petitioner con-
10           TYSON FOODS, INC. v. BOUAPHAKEO

                      Opinion of the Court

tends that Mericle’s study manufactures predominance by
assuming away the very differences that make the case
inappropriate for classwide resolution. Reliance on a
representative sample, petitioner argues, absolves each
employee of the responsibility to prove personal injury,
and thus deprives petitioner of any ability to litigate its
defenses to individual claims.
   Calling this unfair, petitioner and various of its amici
maintain that the Court should announce a broad rule
against the use in class actions of what the parties call
representative evidence. A categorical exclusion of that
sort, however, would make little sense. A representative
or statistical sample, like all evidence, is a means to estab-
lish or defend against liability. Its permissibility turns not
on the form a proceeding takes—be it a class or individual
action—but on the degree to which the evidence is reliable
in proving or disproving the elements of the relevant cause
of action. See Fed. Rules Evid. 401, 403, and 702.
   It follows that the Court would reach too far were it to
establish general rules governing the use of statistical
evidence, or so-called representative evidence, in all class-
action cases. Evidence of this type is used in various
substantive realms of the law. Brief for Complex Litiga-
tion Law Professors as Amici Curiae 5–9; Brief for Econo-
mists et al. as Amici Curiae 8–10. Whether and when
statistical evidence can be used to establish classwide
liability will depend on the purpose for which the evidence
is being introduced and on “the elements of the underlying
cause of action,” Erica P. John Fund, Inc. v. Halliburton
Co., 563 U. S. 804, 809 (2011).
   In many cases, a representative sample is “the only
practicable means to collect and present relevant data”
establishing a defendant’s liability. Manual of Complex
Litigation §11.493, p. 102 (4th ed. 2004). In a case where
representative evidence is relevant in proving a plaintiff ’s
individual claim, that evidence cannot be deemed im-
                  Cite as: 577 U. S. ____ (2016)           11

                      Opinion of the Court

proper merely because the claim is brought on behalf of a
class. To so hold would ignore the Rules Enabling Act’s
pellucid instruction that use of the class device cannot
“abridge . . . any substantive right.” 28 U. S. C. §2072(b).
  One way for respondents to show, then, that the sample
relied upon here is a permissible method of proving class-
wide liability is by showing that each class member could
have relied on that sample to establish liability if he or she
had brought an individual action. If the sample could
have sustained a reasonable jury finding as to hours
worked in each employee’s individual action, that sample
is a permissible means of establishing the employees’
hours worked in a class action.
  This Court’s decision in Anderson v. Mt. Clemens ex-
plains why Mericle’s sample was permissible in the cir-
cumstances of this case. In Mt. Clemens, 7 employees and
their union, seeking to represent over 300 others, brought
a collective action against their employer for failing to
compensate them for time spent walking to and from their
workstations. The variance in walking time among work-
ers was alleged to be upwards of 10 minutes a day, which
is roughly consistent with the variances in donning and
doffing times here. 328 U. S., at 685.
  The Court in Mt. Clemens held that when employers
violate their statutory duty to keep proper records, and
employees thereby have no way to establish the time spent
doing uncompensated work, the “remedial nature of [the
FLSA] and the great public policy which it embodies . . .
militate against making” the burden of proving uncom-
pensated work “an impossible hurdle for the employee.”
Id., at 687; see also Hoffmann-La Roche Inc. v. Sperling,
493 U. S. 165, 173 (1989) (“The broad remedial goal of the
statute should be enforced to the full extent of its terms”).
Instead of punishing “the employee by denying him any
recovery on the ground that he is unable to prove the
12          TYSON FOODS, INC. v. BOUAPHAKEO

                     Opinion of the Court

 precise extent of uncompensated work,” the Court held
“an employee has carried out his burden if he proves that
he has in fact performed work for which he was improper-
ly compensated and if he produces sufficient evidence to
show the amount and extent of that work as a matter of
just and reasonable inference.” 328 U. S., at 687. Under
these circumstances, “[t]he burden then shifts to the em-
ployer to come forward with evidence of the precise
amount of work performed or with evidence to negative
the reasonableness of the inference to be drawn from the
employee’s evidence.” Id., at 687–688.
    In this suit, as in Mt. Clemens, respondents sought to
introduce a representative sample to fill an evidentiary
gap created by the employer’s failure to keep adequate
records. If the employees had proceeded with 3,344 indi-
vidual lawsuits, each employee likely would have had to
introduce Mericle’s study to prove the hours he or she
worked. Rather than absolving the employees from prov-
ing individual injury, the representative evidence here
was a permissible means of making that very showing.
    Reliance on Mericle’s study did not deprive petitioner of
its ability to litigate individual defenses. Since there were
no alternative means for the employees to establish their
hours worked, petitioner’s primary defense was to show
that Mericle’s study was unrepresentative or inaccurate.
That defense is itself common to the claims made by all
class members. Respondents’ “failure of proof on th[is]
common question” likely would have ended “the litigation
and thus [would not have] cause[d] individual questions
. . . to overwhelm questions common to the class.” Amgen
Inc. v. Connecticut Retirement Plans and Trust Funds, 568
U. S. ___, ___ (2013) (slip op., at 11). When, as here, “the
concern about the proposed class is not that it exhibits
some fatal dissimilarity but, rather, a fatal similarity—[an
alleged] failure of proof as to an element of the plaintiffs’
cause of action—courts should engage that question as a
                  Cite as: 577 U. S. ____ (2016)           13

                      Opinion of the Court

matter of summary judgment, not class certification.”
Nagareda, Class Certification in the Age of Aggregate
Proof, 84 N. Y. U. L. Rev. 97, 107 (2009).
   Petitioner’s reliance on Wal-Mart Stores, Inc. v. Dukes,
564 U. S. 338 (2011), is misplaced. Wal-Mart does not
stand for the broad proposition that a representative
sample is an impermissible means of establishing class-
wide liability.
   Wal-Mart involved a nationwide Title VII class of over
11∕2 million employees. In reversing class certification, this
Court did not reach Rule 23(b)(3)’s predominance prong,
holding instead that the class failed to meet even Rule
23(a)’s more basic requirement that class members share a
common question of fact or law. The plaintiffs in Wal-
Mart did not provide significant proof of a common policy
of discrimination to which each employee was subject.
“The only corporate policy that the plaintiffs’ evidence
convincingly establishe[d was] Wal-Mart’s ‘policy’ of allow-
ing discretion by local supervisors over employment mat-
ters”; and even then, the plaintiffs could not identify “a
common mode of exercising discretion that pervade[d] the
entire company.” Id., at 355–356 (emphasis deleted).
   The plaintiffs in Wal-Mart proposed to use representa-
tive evidence as a means of overcoming this absence of a
common policy. Under their proposed methodology, a
“sample set of the class members would be selected, as to
whom liability for sex discrimination and the backpay
owing as a result would be determined in depositions
supervised by a master.” Id., at 367. The aggregate dam-
ages award was to be derived by taking the “percentage of
claims determined to be valid” from this sample and ap-
plying it to the rest of the class, and then multiplying the
“number of (presumptively) valid claims” by “the average
backpay award in the sample set.” Ibid. The Court held
that this “Trial By Formula” was contrary to the Rules
Enabling Act because it “ ‘enlarge[d]’ ” the class members’
14          TYSON FOODS, INC. v. BOUAPHAKEO

                     Opinion of the Court

“ ‘substantive right[s]’ ” and deprived defendants of their
right to litigate statutory defenses to individual claims.
Ibid.
    The Court’s holding in the instant case is in accord with
Wal-Mart. The underlying question in Wal-Mart, as here,
was whether the sample at issue could have been used to
establish liability in an individual action. Since the Court
held that the employees were not similarly situated, none
of them could have prevailed in an individual suit by
relying on depositions detailing the ways in which other
employees were discriminated against by their particular
store managers. By extension, if the employees had
brought 11∕2 million individual suits, there would be little
or no role for representative evidence. Permitting the use
of that sample in a class action, therefore, would have
violated the Rules Enabling Act by giving plaintiffs and
defendants different rights in a class proceeding than they
could have asserted in an individual action.
    In contrast, the study here could have been sufficient to
sustain a jury finding as to hours worked if it were intro-
duced in each employee’s individual action. While the
experiences of the employees in Wal-Mart bore little rela-
tionship to one another, in this case each employee worked
in the same facility, did similar work, and was paid under
the same policy. As Mt. Clemens confirms, under these
circumstances the experiences of a subset of employees
can be probative as to the experiences of all of them.
    This is not to say that all inferences drawn from repre-
sentative evidence in an FLSA case are “just and reason-
able.” Mt. Clemens, 328 U. S., at 687. Representative
evidence that is statistically inadequate or based on im-
plausible assumptions could not lead to a fair or accurate
estimate of the uncompensated hours an employee has
worked. Petitioner, however, did not raise a challenge to
respondents’ experts’ methodology under Daubert; and, as
a result, there is no basis in the record to conclude it was
                 Cite as: 577 U. S. ____ (2016)           15

                     Opinion of the Court

legal error to admit that evidence.
   Once a district court finds evidence to be admissible, its
persuasiveness is, in general, a matter for the jury. Rea-
sonable minds may differ as to whether the average time
Mericle calculated is probative as to the time actually
worked by each employee. Resolving that question, how-
ever, is the near-exclusive province of the jury. The Dis-
trict Court could have denied class certification on this
ground only if it concluded that no reasonable juror could
have believed that the employees spent roughly equal time
donning and doffing. Cf. Anderson v. Liberty Lobby, Inc.,
477 U. S. 242, 250–252 (1986). The District Court made
no such finding, and the record here provides no basis for
this Court to second-guess that conclusion.
   The Court reiterates that, while petitioner, respondents,
or their respective amici may urge adoption of broad and
categorical rules governing the use of representative and
statistical evidence in class actions, this case provides no
occasion to do so. Whether a representative sample may
be used to establish classwide liability will depend on the
purpose for which the sample is being introduced and on
the underlying cause of action. In FLSA actions, inferring
the hours an employee has worked from a study such as
Mericle’s has been permitted by the Court so long as the
study is otherwise admissible. Mt. Clemens, supra, at 687;
see also Fed. Rules Evid. 402 and 702. The fairness and
utility of statistical methods in contexts other than those
presented here will depend on facts and circumstances
particular to those cases.
                               B
  In its petition for certiorari petitioner framed its second
question presented as whether a class may be certified if it
contains “members who were not injured and have no
legal right to any damages.” Pet. for Cert. i. In its merits
brief, however, petitioner reframes its argument. It now
16          TYSON FOODS, INC. v. BOUAPHAKEO

                     Opinion of the Court

concedes that “[t]he fact that federal courts lack authority
to compensate persons who cannot prove injury does not
mean that a class action (or collective action) can never be
certified in the absence of proof that all class members
were injured.” Brief for Petitioner 49. In light of petition-
er’s abandonment of its argument from the petition, the
Court need not, and does not, address it.
   Petitioner’s new argument is that, “where class plain-
tiffs cannot offer” proof that all class members are injured,
“they must demonstrate instead that there is some mech-
anism to identify the uninjured class members prior to
judgment and ensure that uninjured members (1) do not
contribute to the size of any damage award and (2) cannot
recover such damages.” Ibid. Petitioner contends that
respondents have not demonstrated any mechanism for
ensuring that uninjured class members do not recover
damages here.
   Petitioner’s new argument is predicated on the assump-
tion that the damages award cannot be apportioned so
that only those class members who suffered an FLSA
violation recover. According to petitioner, because Fox’s
mechanism for determining who had worked over 40 hours
depended on Mericle’s estimate of donning and doffing
time, and because the jury must have rejected Mericle’s
estimate when it reduced the damages award by more
than half, it will not be possible to know which workers
are entitled to share in the award.
   As petitioner and its amici stress, the question whether
uninjured class members may recover is one of great
importance. See, e.g., Brief for Consumer Data Industry
Association as Amicus Curiae. It is not, however, a ques-
tion yet fairly presented by this case, because the damages
award has not yet been disbursed, nor does the record
indicate how it will be disbursed.
   Respondents allege there remain ways of distributing
the award to only those individuals who worked more than
                 Cite as: 577 U. S. ____ (2016)                 17

                     Opinion of the Court

40 hours. For example, by working backwards from the
damages award, and assuming each employee donned and
doffed for an identical amount of time (an assumption that
follows from the jury’s finding that the employees suffered
equivalent harm under the policy), it may be possible to
calculate the average donning and doffing time the jury
necessarily must have found, and then apply this figure to
each employee’s known gang-time hours to determine
which employees worked more than 40 hours.
   Whether that or some other methodology will be suc-
cessful in identifying uninjured class members is a ques-
tion that, on this record, is premature. Petitioner may
raise a challenge to the proposed method of allocation
when the case returns to the District Court for disbursal of
the award.
   Finally, it bears emphasis that this problem appears to
be one of petitioner’s own making. Respondents proposed
bifurcating between the liability and damages phases of
this proceeding for the precise reason that it may be diffi-
cult to remove uninjured individuals from the class after
an award is rendered. It was petitioner who argued
against that option and now seeks to profit from the diffi-
culty it caused. Whether, in light of the foregoing, any
error should be deemed invited, is a question for the Dis-
trict Court to address in the first instance.
                       *     *    *
  The judgment of the Court of Appeals for the Eighth
Circuit is affirmed, and the case is remanded for further
proceedings consistent with this opinion.

                                                  It is so ordered.
                 Cite as: 577 U. S. ____ (2016)            1

                   ROBERTS, C. J., concurring

SUPREME COURT OF THE UNITED STATES
                         _________________

                         No. 14–1146
                         _________________


     TYSON FOODS, INC., PETITIONER v. PEG
  BOUAPHAKEO, ET AL., INDIVIDUALLY AND ON BEHALF
           OF ALL OTHERS SIMILARLY SITUATED

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
           APPEALS FOR THE EIGHTH CIRCUIT
                       [March 22, 2016]

   CHIEF JUSTICE ROBERTS, with whom JUSTICE ALITO
joins as to Part II, concurring.
   Petitioner Tyson Foods presents two primary argu-
ments. First, it claims that class certification was im-
proper because each individual plaintiff spent different
amounts of time donning and doffing protective gear.
Therefore, according to Tyson, whether and to what extent
it owed damages to each individual employee for uncom-
pensated overtime was not a question capable of resolu-
tion on a class-wide basis. Second, Tyson argues that the
verdict cannot stand because, while no one disputes that
the class as certified contains hundreds of uninjured em-
ployees, the plaintiffs have not come up with any way to
ensure that those employees do not recover damages from
the jury’s lump-sum award.
   The Court rejects the first argument and leaves the
second for initial resolution by the lower courts. I join the
Court’s opinion in full. I write separately to explain my
understanding of the Court’s resolution of the case and to
express my concern that the District Court may not be
able to fashion a method for awarding damages only to
those class members who suffered an actual injury.
2            TYSON FOODS, INC. v. BOUAPHAKEO

                   ROBERTS, C. J., concurring

                              I
   A class may be certified under Federal Rule of Civil
Procedure 23(b)(3) only if “questions of law or fact common
to class members predominate over any questions affect-
ing only individual members.” A common question is one
in which “the issue is susceptible to generalized, class-
wide proof.” Ante, at 9 (quoting 2 W. Rubenstein, Newberg
on Class Actions §4:50, pp. 196–197 (5th ed. 2012)) (inter-
nal quotation marks omitted).
   To prove liability and damages, respondents had to
establish the amount of compensable (but uncompensated)
donning and doffing time for each individual plaintiff. The
Court properly concludes that despite the differences in
donning and doffing time for individual class members,
respondents could adequately prove the amount of time for
each individual through generalized, class-wide proof.
That proof was Dr. Mericle’s representative study. As the
Court observes, “each class-member could have relied on
that [study] to establish liability if he or she had brought
an individual action.” Ante, at 11. And when representa-
tive evidence would suffice to prove a plaintiff ’s individual
claim, that evidence cannot be deemed improper merely
because the claim is brought as part of a class action. See
ante, at 10–11.
   I agree with JUSTICE THOMAS that our decision in An-
derson v. Mt. Clemens Pottery Co., 328 U. S. 680 (1946),
does not provide a “special, relaxed rule authorizing plain-
tiffs to use otherwise inadequate representative evidence
in FLSA-based cases.” Post, at 7 (dissenting opinion). But
I do not read the Court’s opinion to be inconsistent with
that conclusion. Rather, I take the Court to conclude that
Dr. Mericle’s study constituted sufficient proof from which
the jury could find “the amount and extent of [each indi-
vidual respondent’s] work as a matter of just and reasona-
ble inference”—the same standard of proof that would
apply in any case. Ante, at 12 (internal quotation marks
                 Cite as: 577 U. S. ____ (2016)            3

                   ROBERTS, C. J., concurring

omitted). It is with that understanding that I join the
opinion of the Court.
                              II
   As for Tyson’s second argument, it is undisputed that
hundreds of class members suffered no injury in this case.
See Brief for Respondents 52–53; Tr. of Oral Arg. 30. The
question is: which ones? The only way to know is to figure
out how much donning and doffing time the jury found
Tyson owed the workers in each department. But the jury
returned a lump-sum verdict of $2.9 million on a class-
wide basis, without specifying any particular amount of
donning and doffing time used to calculate that number.
If we knew that the jury had accepted the plaintiffs’ pro-
posed average donning and doffing times in calculating
the verdict, we could easily overcome this problem. But
we know the jury did no such thing. And with no way to
reverse engineer the verdict to determine how much don-
ning and doffing time the jury found Tyson owed workers
in each department, we do not know which plaintiffs the
jury found to be injured (or not).
   Tyson contends that unless the District Court can fash-
ion a means of identifying those class members not enti-
tled to damages, it must throw out the jury’s verdict and
decertify the class. I agree with the Court’s decision to
leave that issue to be addressed in the first instance by the
District Court. But I am not convinced that the District
Court will be able to devise a means of distributing the
aggregate award only to injured class members.
   As the Court explains, each plaintiff in this case suf-
fered actual harm only if he: (1) was not compensated for
at least some compensable donning and doffing time; and
(2) worked more than 40 hours in a workweek, including
any compensable donning and doffing time. See ante, at
16–17. In other words, it is not enough that a plaintiff
was uncompensated for compensable donning and doffing
4           TYSON FOODS, INC. v. BOUAPHAKEO

                   ROBERTS, C. J., concurring

time; unless that plaintiff also worked more than 40 hours
in a week (including compensable donning and doffing
time), he is owed no overtime pay and therefore suffered
no injury.
   If the jury credited Dr. Mericle’s averages—18 minutes
per day of donning and doffing time for employees in the
fabrication (cut and retrim) departments, 21.25 for em-
ployees in the kill department—the District Court could
have assumed that the jury found that each plaintiff from
those departments donned and doffed the average
amounts of time and used those averages to determine
which plaintiffs had worked more than 40 hours (and
awarded damages on that understanding).
   The problem is that the jury obviously did not credit Dr.
Mericle’s averages. According to Dr. Fox, another of the
plaintiffs’ experts, those averages would have resulted in a
$6.7 million verdict across the 3,344 member class. Ante,
at 7. The jury, however, awarded the plaintiffs only $2.9
million.
   How, then, did the jury arrive at that $2.9 million fig-
ure? The jury might have determined that Dr. Mericle’s
average was correct for the kill department, but overstated
for the fabrication departments. Or vice versa. Or the
jury might have found that Dr. Mericle’s averages over-
stated the donning and doffing time in all departments, by
varying degrees. Any of those conclusions would have
been permissible on these facts, and any of those options
would have reduced the jury verdict from the $6.7 million
proposed by Dr. Fox. But in arriving at the $2.9 million
verdict, we have no way of knowing how much donning
and doffing time the jury actually found to have occurred
in the kill and fabrication departments, respectively.
   And there’s the rub. We know that the jury must have
found at least one of Dr. Mericle’s two averages to be too
high. And we know, as Dr. Fox testified, that if Dr. Mer-
icle’s averages were even slightly too high, hundreds of
                 Cite as: 577 U. S. ____ (2016)            5

                   ROBERTS, C. J., concurring

class members would fall short of the 40-hour workweek
threshold that would entitle them to damages. See post,
at 5–6. But because we do not know how much donning
and doffing time the jury found to have occurred in each
department, we have no way of knowing which plaintiffs
failed to cross that 40-hour threshold.
   To illustrate: Take a fabrication employee and a kill
employee, each of whom worked a 39-hour workweek
before counting any compensable donning and doffing
time. If the jury credited Dr. Mericle’s kill department
average but discounted his fabrication average to below
one hour per week, the jury would have found that the kill
employee was injured, while the fabrication employee was
not. But the jury also might have done the exact opposite.
We just don’t know—and so we have no way to determine
which plaintiffs the jury concluded were injured.
   The plaintiffs believe they can surmount this obstacle.
As the Court explains, they propose to work backward
from the damages award by assuming that each employee
donned and doffed for an identical amount of time. Ante,
at 16–17. That won’t work, however, because there is no
indication that the jury made the same assumption.
Indeed, the most reasonable guess is that the jury did not
find that employees in different departments donned and
doffed for identical amounts of time. After all, the plain-
tiffs’ own expert indicated that employees in different
departments donned and doffed for different amounts of
time.
   Given this difficulty, it remains to be seen whether the
jury verdict can stand. The Court observes in dicta that
the problem of distributing the damages award “appears
to be one of petitioner’s own making.” Ante, at 17. Per-
haps. But Tyson’s insistence on a lump-sum jury award
cannot overcome the limitations placed on the federal
courts by the Constitution. Article III does not give fed-
eral courts the power to order relief to any uninjured plain-
6            TYSON FOODS, INC. v. BOUAPHAKEO

                   ROBERTS, C. J., concurring

tiff, class action or not. The Judiciary’s role is limited “to
provid[ing] relief to claimants, in individual or class ac-
tions, who have suffered, or will imminently suffer, actual
harm.” Lewis v. Casey, 518 U. S. 343, 349 (1996). There-
fore, if there is no way to ensure that the jury’s damages
award goes only to injured class members, that award
cannot stand. This issue should be considered by the
District Court in the first instance. As the Court properly
concludes, the problem is not presently ripe for our review.
                 Cite as: 577 U. S. ____ (2016)           1

                    THOMAS, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                         No. 14–1146
                         _________________


     TYSON FOODS, INC., PETITIONER v. PEG
  BOUAPHAKEO, ET AL., INDIVIDUALLY AND ON BEHALF
           OF ALL OTHERS SIMILARLY SITUATED

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
           APPEALS FOR THE EIGHTH CIRCUIT
                       [March 22, 2016]

  JUSTICE THOMAS, with whom JUSTICE ALITO joins,
dissenting.

   Our precedents generally prohibit plaintiffs from main-
taining a class action when an important element of liabil-
ity depends on facts that vary among individual class
members. This case concerns whether and when class-
action plaintiffs can overcome that general rule by using
representative evidence as common proof of an otherwise
individualized issue. Our precedents resolve that ques-
tion: Before class-action plaintiffs can use representative
evidence in this way, district courts must undertake a
rigorous analysis to ensure that such evidence is suffi-
ciently probative of the individual issue to make it suscep-
tible to classwide proof. The District Court did not satisfy
that obligation here, and its failure to do so prejudiced
defendant Tyson Foods at trial. The majority reaches a
contrary conclusion by redefining class-action require-
ments and devising an unsound special evidentiary rule
for cases under the Fair Labor Standards Act of 1938
(FLSA), 29 U. S. C. §201 et seq. I respectfully dissent.
                              I
   “The class action is an exception to the usual rule that
litigation is conducted by and on behalf of the individual
2            TYSON FOODS, INC. v. BOUAPHAKEO

                     THOMAS, J., dissenting

named parties only.” Comcast Corp. v. Behrend, 569 U. S.
___, ___ (2013) (slip op., at 5) (internal quotation marks
omitted). Plaintiffs thus “must affirmatively demonstrate
[their] compliance” with Rule 23. Wal-Mart Stores, Inc. v.
Dukes, 564 U. S. 338, 350 (2011). Where, as here, a puta-
tive class seeks money damages, plaintiffs also must
satisfy the “demanding” standard of predominance, Com-
cast, supra, at ___ (slip op., at 6), by proving that “ques-
tions of law or fact common to class members predominate
over any questions affecting only individual members.”
Fed. Rule Civ. Proc. 23(b)(3).
   District courts must also ensure continued compliance
with Rule 23 throughout the case. When a district court
erroneously certifies a class, then holds a trial, reversal is
required when the record shows that improper certifica-
tion prejudiced the defendant. And an incorrect class
certification decision almost inevitably prejudices the
defendant. When a district court allows class plaintiffs to
prove an individualized issue with classwide evidence, the
court relieves them of their burden to prove each element
of their claim for each class member and impedes the
defendant’s efforts to mount an effective defense.
   Here, the District Court misconstrued the elements of
the plaintiffs’ claims. And it failed to recognize that one
critical element of those claims raised an individual issue
that would predominate over any common issues. The
court therefore did not ask whether that individual issue
was susceptible to common proof. That error, at the class
certification stage, then prejudiced Tyson at trial. It was
only at trial that the plaintiffs introduced the critical
evidence at issue in this case. They introduced, as repre-
sentative of the class, a study by the plaintiffs’ expert, Dr.
Kenneth Mericle. The District Court still declined to
consider whether this evidence was appropriate common
proof — even though the study showed wide variations
                    Cite as: 577 U. S. ____ (2016)                   3

                        THOMAS, J., dissenting

among class members on an important individual issue.
These errors prejudiced Tyson and warrant reversal.
                              A
   The District Court erred at the class certification stage
by holding that the plaintiffs satisfied Rule 23’s predomi-
nance requirement. The plaintiffs alleged that Tyson
failed to adequately pay workers overtime for donning and
doffing protective gear, in violation of the Iowa Wage
Payment Collection Law, Iowa Code §91A.3 (2013). This
Iowa law mirrors the FLSA. 1 An employer violates these
laws if it employs someone “for a workweek longer than
forty hours” and fails to adequately compensate him for
the overtime. 29 U. S. C. §207(a)(1). Here, the plaintiffs
could establish Tyson’s liability to all class members only
if: (1) the donning and doffing at issue is compensable
work; (2) all employees worked over 40 hours, including
donning and doffing time; and (3) Tyson failed to compen-
sate each employee for all overtime.
   The District Court should have begun its predominance
inquiry by determining which elements of the plaintiffs’
claims present common or individual issues, and assessed
whether individual issues would overwhelm common ones.
See Halliburton Co. v. Erica P. John Fund, Inc., 573 U. S.
___, ___ (2014) (slip op., at 14–15); Erica P. John Fund,
Inc. v. Halliburton Co., 563 U. S. 804, 809 (2011). The
plaintiffs’ claims here had one element that was clearly
individualized: whether each employee worked over 40
hours without receiving full overtime pay. The amount of
time that employees spent on donning and doffing varied
by person because individuals take different amounts of
time to don and doff the same gear, and their gear varied.

——————
  1 The plaintiffs also brought a collective action under the FLSA. Be-

cause the jury verdict combined the two actions, deficiencies in the
class action require reversal of the entire judgment.
4           TYSON FOODS, INC. v. BOUAPHAKEO

                    THOMAS, J., dissenting

This issue was critical to determining Tyson’s liability
because some employees would not have worked over 40
hours per week without counting time spent on donning
and doffing. The critical issue for class certification thus
was whether the individualized nature of employees’
donning and doffing times defeated predominance.
   The District Court, however, certified a 3,344–member
class without acknowledging the significance of this indi-
vidual issue, let alone addressing whether it was suscepti-
ble to common proof. The court acknowledged that
“[i]ndividual questions may exist” and that Tyson was
objecting to being “forced to defend against un common
evidence” because the plaintiffs had no common evidence
establishing what gear all employees wore “or how long
[they] spend donning and doffing their [gear].” 564
F. Supp. 2d 870, 900, 909 (ND Iowa 2008). But, in the
District Court’s view, common issues predominated be-
cause the plaintiffs could establish classwide liability just
by showing that Tyson was not paying any employee for
the time it took to don or doff basic gear. Id., at 909; see
id., at 900, 904, 905 (similar).
   The District Court thus did not give proper considera-
tion to the significance of variable donning and doffing
times. Establishing an FLSA violation across the entire
class was impossible without evidence that each employee
would have worked over 40 hours per week if donning and
doffing time were included. But the District Court did not
fully appreciate that this was a critical individual issue
that defined Tyson’s liability, and it did not analyze, in
any way, whether this issue was susceptible to common
proof. As a result, the District Court erred when it certi-
fied the class.
                             B
  It was only later at trial that the plaintiffs introduced
the critical evidence that they claimed could establish all
                 Cite as: 577 U. S. ____ (2016)           5

                    THOMAS, J., dissenting

employees’ donning and doffing times on a classwide basis.
This evidence came from the plaintiffs’ expert, Dr. Mericle,
who studied how long certain Tyson employees took to don
and doff various gear. This was the “most important”
evidence at trial. Ante, at 5. Without it, the plaintiffs
almost certainly could not have obtained a classwide
verdict. But rather than showing that employees’ donning
and doffing times were susceptible to classwide proof,
Mericle’s evidence showed that employees’ donning and
doffing times varied materially. Mericle’s evidence thus
confirmed the inappropriateness of class treatment.
  Mericle used about 53 employees per donning- or doffing-
related activity to extrapolate averages for the 3,344–
person class. By averaging the times that sample employ-
ees spent per activity, Mericle estimated that all cut or
retrim department employees spent 18 minutes per day on
uncompensated activities (including donning and doffing),
while kill department employees averaged 21.25 minutes.
  Mericle’s data, however, revealed material variances in
the amount of time that individual employees spent on the
same activities. Cut and retrim employees took between
0.583 minutes and over 10 minutes to don preshift equip-
ment at their lockers. Postshift doffing took one employee
less than two minutes, and another over nine minutes.
Kill department employees had similar variances. No two
employees performed the same activity in the same
amount of time, and Mericle observed “a lot of variation
within the activity.” App. 387.
  The plaintiffs’ trial evidence also showed that variances
in the amount of time that employees spent on donning
and doffing activities significantly affected the number of
class members who could assert overtime claims. The
plaintiffs’ other expert, Dr. Liesl Fox, added Mericle’s
average times to individual employees’ timesheets to
determine which class members had overtime claims. She
discovered that 212 of the 3,344 class members had no
6            TYSON FOODS, INC. v. BOUAPHAKEO

                     THOMAS, J., dissenting

claims at all because they had not worked over 40 hours
per week. If Mericle’s averages even slightly overesti-
mated average donning and doffing times, another 282 class
members would have no overtime claims. If average
donning or doffing times dropped from 18–21 minutes to
15 minutes, Fox stated, another 110 employees had no
overtime claims. According to Fox, incremental changes to
donning and doffing times mattered so much that her
estimated damages figure ($6.6 million) would be mean-
ingless if the jury discounted Mericle’s data at all. Yet the
jury ultimately rejected that damages figure—seemingly
disagreeing that Mericle’s average times reflected the
amount of time that every class member spent donning
and doffing.
   Because the District Court did not evaluate Mericle’s
and Fox’s evidence in its initial class certification decision,
it should have revisited certification when faced with this
evidence at trial. It declined to do so even after Tyson
objected to using this evidence to establish the amount of
time all class members spent donning and doffing. See
2011 WL 3793962 (ND Iowa, Aug. 25, 2011) (rejecting
decertification motion); 2012 WL 4471119 (ND Iowa, Sept.
26, 2012) (summarily denying post-trial decertification).
The court thus never made findings or analyzed whether,
under Rule 23(b)(3), Mericle’s study could be used as
common proof of an individual issue that would otherwise
preclude class treatment.
   The District Court’s jury instructions did not cure this
deficiency. No instruction could remedy a court’s failure to
address why an individual issue was susceptible to com-
mon proof. In any event, the court instructed the jury that
“expert testimony”—like Mericle’s—should get “as much
weight as you think it deserves.” App. 471. The court also
let the jury rely on representative evidence to establish
each class member’s claim even if the jury believed that
employees’ donning and doffing times varied considerably.
                 Cite as: 577 U. S. ____ (2016)            7

                    THOMAS, J., dissenting

See ibid.
   In sum, the plaintiffs at no time had to justify whether
the variability among class members here was too much
for representative evidence to fill the gap with common
proof. Nor did the District Court address whether Mer-
icle’s study—which showed significant variability in how
much time employees spent on donning and doffing—was
permissible common proof. These errors created an unac-
ceptable risk that Tyson would be held liable to a large
class without adequate proof that each individual class
member was owed overtime. Before defendants can be
forced to defend against a class action, courts must be sure
that Rule 23’s criteria are met. The District Court’s fail-
ure to do so warrants reversal.
                              II
  The majority reaches a contrary result by erring in
three significant ways. First, the majority alters the
predominance inquiry so that important individual issues
are less likely to defeat class certification. Next, the ma-
jority creates a special, relaxed rule authorizing plaintiffs
to use otherwise inadequate representative evidence in
FLSA-based cases by misreading Anderson v. Mt. Clemens
Pottery Co., 328 U. S. 680 (1946). Finally, the majority
points to Tyson’s litigation strategy and purported differ-
ences from prior Rule 23 precedents. None of these justifi-
cations withstands scrutiny.
                            A
  The majority begins by redefining the predominance
standard. According to the majority, if some “ ‘central
issues’ ” present common questions, “ ‘the action may be
considered proper under Rule 23(b)(3) even though other
important matters will have to be tried separately, such as
damages or some affirmative defenses peculiar to some
individual class members.’ ” Ante, at 9 (quoting, 7AA C.
8              TYSON FOODS, INC. v. BOUAPHAKEO

                        THOMAS, J., dissenting

Wright, A. Miller, & M. Kane, Federal Practice & Proce-
dure §1778, pp. 123–124 (3d ed. 2005; footnotes omitted)).
  We recently—and correctly—held the opposite.                  In
Comcast, we deemed the lack of a common methodology
for proving damages fatal to predominance because
“[q]uestions of individual damage calculations will inevi-
tably overwhelm questions common to the class.” 569
U. S., at ___ (slip op., at 7). 2 If, as the majority states, this
case presents “no occasion” to announce “broad and cate-
gorical rules governing the use of representative and
statistical evidence in class actions,” ante, at 15, it should
most certainly not present an occasion to transform basic
aspects of the predominance inquiry.
                            B
   The majority further errs in concluding that the repre-
sentative evidence here showed that class members’
claims were susceptible to common proof. See ante, at 8–
15. As the majority observes, representative evidence can
be used to prove an individual issue on a classwide basis if
each class member, in an individual action, could rely on
that evidence to prove his individual claim. Ante, at 11.
But that premise should doom the plaintiffs’ case. Even
testifying class members would seem unable to use Mer-
icle’s averages. For instance, Mericle’s study estimated
that kill department employees took an average 6.4
minutes to don equipment at their lockers before their


——————
    2 The
        majority relies on the same treatise citations that the Comcast
dissent invoked to argue that individualized damages calculations
should never defeat predominance. 569 U. S., at ___–___ (slip op., at
3–4) (opinion of BREYER, J.). Since then, these treatises have acknowl-
edged the tension between their views of predominance and Comcast.
See 7AA C. Wright, A. Miller, & M. Kane, Federal Practice and Proce-
dure, §1778, p. 37 (3d ed. Supp. 2015); 2 W. Rubenstein, Newberg on
Class Actions §4:54, p. 21 (5th ed. Supp. June 2015).
                 Cite as: 577 U. S. ____ (2016)            9

                    THOMAS, J., dissenting

shift—but employee Donald Brown testified that this
activity took him around 2 minutes. Others also testified
to donning and doffing times that diverged markedly from
Mericle’s estimates. So Mericle’s study could not sustain a
jury verdict in favor of these plaintiffs, had they brought
individual suits.
   According to the majority, this disparity between aver-
age times and individual times poses no problem because
Anderson v. Mt. Clemens Pottery Co., 328 U. S. 680, allows
plaintiffs to use such representative evidence as common
proof. See ante, at 11–14. In the majority’s view, Mt.
Clemens established that (1) if the employer did not record
the time that employees spent on compensable work,
employees can use representative evidence to establish the
employer’s liability, ante, at 11–12; and (2) employees can
use “the experiences of a subset of employees” to establish
“the experiences of all of them” if “each employee worked
in the same facility, did similar work[,] and was paid
under the same policy,” ante, at 14.
   The majority’s reliance on Mt. Clemens is questionable
given that decision’s shaky foundations. Seventy years
ago, Mt. Clemens construed the FLSA broadly to vindicate
the Court’s understanding of the FLSA’s “remedial” pur-
poses. 328 U. S., at 687. Within a year, Congress rejected
that interpretation. Citing the “emergency” this Court
had created by spurring “excessive and needless litiga-
tion,” Congress repudiated this Court’s understanding of
what the FLSA meant by “work” and the “workweek” and
limited employees’ ability to sue collectively. 29 U. S. C.
§§251(a)–(b); see Integrity Staffing Solutions, Inc. v. Busk,
574 U. S. ___, ___ (2014) (slip op., at 3–5) (noting repudia-
tion in the Portal-to-Portal Act of 1947); Hoffmann-La
Roche Inc. v. Sperling, 493 U. S. 165, 173 (1989) (noting
repudiation of representative actions ). Since then, this
10             TYSON FOODS, INC. v. BOUAPHAKEO

                        THOMAS, J., dissenting

Court has decided many FLSA cases, but has never relied
on Mt. Clemens to do so. 3
   Putting these concerns aside, the majority today goes
beyond what Mt. Clemens held. First, Mt. Clemens does
not hold that employees can use representative evidence
in FLSA cases to prove an otherwise uncertain element of
liability. Mt. Clemens involved an employer’s alleged
failure to pay employees for time they spent walking to
and from their work spaces and on preshift preparatory
activities. See 328 U. S., at 684–685. The Court held that
the FLSA required employers to compensate employees for
those activities. Id., at 690–692 (overruled by 29 U. S. C.
§§252, 254). The employer was thus presumptively liable
to all employees because they all claimed to work 40 hours
per week. See Record in Mt. Clemens, O.T. 1945, No. 342
(Record), pp. 10–11 (complaint). All additional uncompen-
sated work was necessarily unpaid overtime. That ex-
plains why the Court “assum[ed] that the employee has
proved that he has performed work and has not been paid
in accordance with the statute.” 328 U. S., at 688.
   Mt. Clemens also rejected the notion that employees who
had already established the employer’s liability had to
prove damages using precise, employee-specific records.
Id., at 687. Rather, if the employer failed to keep records
but its liability was certain, employees could use evidence
that “show[ s ] the amount and extent of that work as a

——————
  3 THE CHIEF JUSTICE believes that the majority does not actually de-

pend upon Mt. Clemens as a special evidentiary rule, and instead
applies “the same standard of proof that would apply in any case.”
Ante, at 2. That interpretation is difficult to credit given that the
majority never explains why Dr. Mericle’s representative evidence
could have sustained a jury finding in favor of any individual employee
in an individual case, and instead devotes several paragraphs to the
proposition that “[t]his Court’s decision in [Mt. Clemens] explains why
Dr. Mericle’s sample was permissible in the circumstances of this case.”
Ante, at 11; see id., at 11-12.
                 Cite as: 577 U. S. ____ (2016)          11

                    THOMAS, J., dissenting

matter of just and reasonable inference.” Ibid. The Court,
however, limited this holding to instances where the em-
ployer’s FLSA violation was “certain,” as in Mt. Clemens
itself. Id., at 688; see ibid. (inference permissible “as to
the extent of the damages”). Mt. Clemens does not justify
the use of representative evidence in this case, where
Tyson’s liability to many class members was uncertain.
   Second, the majority misreads Mt. Clemens as “con-
firm[ing]” that when employees “worked in the same
facility, did similar work and w[ere] paid under the same
policy,” representative evidence can prove all of their
claims. Ante, at 14. Mt. Clemens said nothing about
whether or why the employees there shared sufficient
similarities for their claims to be susceptible to common
proof. The Mt. Clemens plaintiffs were the local union and
seven employees. See 328 U. S., at 684. They brought a
representative action, a type of collective action that al-
lowed employees to designate a union to pursue their
claims for them. See §16(b), 52 Stat. 1069; Record 7 (com-
plaint). Some 300 employees did so. See Mt. Clemens
Pottery Co. v. Anderson, 149 F. 2d, 461 (CA6 1945); Record
33–41. The District Court did not make findings about
what made these employees similar, instead reasoning
that the FLSA’s broad objectives supported a liberal ap-
proach to allowing class suits. Record 29–32 (June 13,
1941, order). This Court also said nothing about whether
the employees suffered the same harm in the same man-
ner; that issue was not before it. In Mt. Clemens’ after-
math, however, Congress eliminated representative ac-
tions, like the one in Mt. Clemens, that required too few
similarities among plaintiffs and allowed plaintiffs “not
themselves possessing claims” to sue. Hoffman-La Roche,
supra, at 173. Mt. Clemens thus offers no guidance
about what degree of similarity among employees suffices
for representative evidence to establish all employees’
experiences.
12             TYSON FOODS, INC. v. BOUAPHAKEO

                         THOMAS, J., dissenting

   In any event, Mt. Clemens did not accept that the repre-
sentative evidence there would be probative even were the
employees sufficiently similar. All Mt. Clemens decided
was that the lack of precise data about the amount of time
each employee worked was not fatal to their case. 328
U. S., at 686–687. The Court then remanded the case,
leaving the lower courts to “draw whatever reasonable
inferences can be drawn from the employees’ evidence,” if
any. Id., at 693–694. 4 Mt. Clemens therefore does not
support the majority’s conclusion that representative
evidence can prove thousands of employees’ FLSA claims
if they share a facility, job functions, and pay policies. See
ante, at 14.
   By focusing on similarities irrelevant to whether em-
ployees spend variable times on the task for which they
are allegedly undercompensated, the majority would allow
representative evidence to establish classwide liability
even where much of the class might not have overtime
claims at all. Whether employees work in one plant or
many, have similar job functions, or are paid at the same
rate has nothing to do with how fast they walk, don, or
doff—the key variables here for FLSA liability.
   The majority suggests that Mt. Clemens’ evidentiary
rule is limited to cases where the employer breaches its
obligation to keep records of employees’ compensable
work. See ante, at 11–12. But that limitation is illusory.
FLSA cases often involve allegations that a particular
activity is uncompensated work. Just last Term, we re-

——————
  4 If anything, Mt. Clemens suggests that the representative evidence

here is impermissible. The Court affirmed that the District Court’s
proposed “formula of compensation,” calculated based on estimated
average times it derived from employees’ representative testimony, was
impermissible. 328 U. S., at 689; see 149 F. 2d, at 465 (“It does not
suffice for the employee to base his right to recover on a mere estimated
average of overtime worked.”).
                  Cite as: 577 U. S. ____ (2016)            13

                     THOMAS, J., dissenting

jected class-action plaintiffs’ theory that waiting in an
antitheft security screening line constitutes work. See
Integrity Staffing Solutions, Inc., 574 U. S. at ___ (slip op.,
at 1). The majority thus puts employers to an untenable
choice. They must either track any time that might be the
subject of an innovative lawsuit, or they must defend class
actions against representative evidence that unfairly
homogenizes an individual issue. Either way, the major-
ity’s misinterpretation of Mt. Clemens will profoundly
affect future FLSA-based class actions—which have al-
ready increased dramatically in recent years. Erichson,
CAFA’s Impact On Class Action Lawyers, 156 U. Pa. L.
Rev. 1593, 1617 (2008).
                                C
   The majority makes several other arguments why Mer-
icle’s study was adequate common proof of all class mem-
bers’ experiences. None has merit.
   First, the majority contends that, because Tyson’s trial
defense—that Mericle’s study was unrepresentative or
inaccurate—was “itself common,” Tyson was “not de-
prive[d] . . . of its ability to litigate individual defenses.”
Ante, at 12. But looking to what defenses remained avail-
able is an unsound way to gauge whether the class-action
device prevented the defendant from mounting individual-
ized defenses. That Tyson was able to mount only a com-
mon defense confirms its disadvantage. Testifying class
members attested to spending less time on donning and
doffing than Mericle’s averages would suggest. Had Tyson
been able to cross-examine more than four of them, it may
have incurred far less liability. See supra, at 9–10.
   Second, the majority argues that Tyson’s failure to
challenge Mericle’s testimony under Daubert v. Merrell
Dow Pharmaceuticals, Inc., 509 U. S. 579 (1993), left to
the jury any remaining questions about the value of this
evidence. Ante, at 14–15. But Comcast rejected this
14           TYSON FOODS, INC. v. BOUAPHAKEO

                     THOMAS, J., dissenting

argument. Failing to challenge evidence under Daubert
precludes defendants from “argu[ing] that [the] testimony
was not admissible,” but it does not preclude defendants
from “argu[ing] that the evidence failed to show that the
case is susceptible to awarding damages on a class-wide
basis.” Comcast, 569 U. S., at ___, n. 4 (slip op., at 5, n. 4)
(internal quotation marks omitted).
   Finally, the majority’s attempts to distinguish this case
from Wal-Mart are unavailing. See ante, at 13–14. Wal-
Mart involved a nationwide Title VII class action alleging
that Wal-Mart’s policy of delegating employment decisions
to individual store managers let managers exercise their
discretion in a discriminatory manner. See 564 U. S., at
342. We held that discretionary decisionmaking could not
be a common policy uniting all class members’ claims
because managers presumptively exercise their discretion
in an individualized manner. See id., at 355–356. Some
may rely on performance-based criteria; others may use
tests; yet others might intentionally discriminate. Ibid.
Because of this variability, “demonstrating the invalidity
of one manager’s use of discretion will do nothing to
demonstrate the invalidity of another’s.” Ibid.
   Moreover, the Wal-Mart plaintiffs’ representative evi-
dence—120 employee anecdotes—did not make this indi-
vidualized issue susceptible to common proof. Id., at 358.
Using 120 anecdotes to represent the experiences of 1.5
million class members was too far below the 1:8 ratio of
anecdotes to class members that our prior cases accepted.
Ibid. Thus, this representative evidence was “too weak to
raise any inference that all the individual, discretionary
personnel decisions are discriminatory.” Ibid.
   The plaintiffs’ reliance on Mericle’s study fails for the
same reasons. Just as individual managers inherently
make discretionary decisions differently, so too do individ-
ual employees inherently spend different amounts of time
donning and doffing. And, just as 120 employee anecdotes
                  Cite as: 577 U. S. ____ (2016)         15

                     THOMAS, J., dissenting

could not establish that all 1.5 million class members
faced discrimination, neither can Mericle’s study establish
that all 3,344 class members spent the same amount of
time donning and doffing. Like the 120 Wal-Mart anec-
dotes, Mericle’s study—which used about 57 employees
per activity to extrapolate times for 3,344—falls short of
the 1:8 ratio this Court deems “significant” to the proba-
tive value of representative evidence. See id., at 358.
                             III
   I agree with the majority’s conclusion in Part II–B that
we should not address whether a class action can be main-
tained if a class contains uninjured members. Given that
conclusion, however, I am perplexed by the majority’s
readiness to suggest, in dicta, that Tyson’s opposition to
bifurcating the proceedings might be invited error. Ante,
at 17. I see no reason to opine on this issue.
                         *      *      *
  I respectfully dissent.
