Document ID: ./input/supremecourt_opinions/opinions/10pdf/10-277.pdf
Page Number: 9.0

Cite as:  564 U. S. ____ (2011) 

5 

Opinion of the Court 

breaks added). 

Second, the proposed class must satisfy at least one of the
three requirements listed in Rule 23(b).  Respondents rely
on  Rule  23(b)(2),  which  applies  when  “the  party  opposing
the class has acted or refused to act on grounds that apply 
generally  to  the  class,  so  that  final  injunctive  relief  or 
corresponding  declaratory  relief  is  appropriate  respecting 
the class as a whole.”2 

Invoking  these  provisions,  respondents  moved  the  Dis-
trict  Court  to  certify  a  plaintiff  class  consisting  of  “ ‘[a]ll 
women  employed  at  any  Wal-Mart  domestic  retail  store 
at  any  time  since  December  26,  1998,  who  have  been  or 
may be subjected to Wal-Mart’s challenged pay and man-
agement  track  promotions  policies  and  practices.’ ”    222 
F. R. D.,  at  141–142  (quoting  Plaintiff ’s  Motion  for  Class 
Certification  in  case  No.  3:01–cv–02252–CRB  (ND  Cal.),
Doc. 99, p. 37).  As evidence that there were indeed “ques-
tions of law or fact common to” all the women of Wal-Mart, 
as  Rule  23(a)(2)  requires,  respondents  relied  chiefly  on
three  forms  of  proof:  statistical  evidence  about  pay  and 
promotion  disparities  between  men  and  women  at  the
company,  anecdotal  reports  of  discrimination  from  about 
120 of Wal-Mart’s female employees, and the testimony of 
a  sociologist,  Dr.  William  Bielby,  who  conducted  a  “social 

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2 Rule  23(b)(1)  allows  a  class  to  be  maintained  where  “prosecuting
separate actions by or against individual class members would create a 
risk  of ”  either  “(A)  inconsistent  or  varying  adjudications,”  or  “(B)
adjudications . . . that, as a practical matter, would be dispositive of the
interests  of  the  other  members  not  parties  to  the  individual  adjudica-
tions  or  would  substantially  impair  or  impeded  their  ability  to  protect 
their  interests.”    Rule  23(b)(3)  states  that  a  class  may  be  maintained
where “questions of law or fact common to class members predominate
over  any  questions  affecting  only  individual  members,”  and  a  class
action  would  be  “superior  to  other  available  methods  for  fairly  and 
efficiently  adjudicating  the  controversy.”    The  applicability  of  these 
provisions to the plaintiff class is not before us.