Document ID: ./input/supremecourt_opinions/opinions/10pdf/10-277.pdf
Page Number: 31

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

27 

Opinion of the Court 

We  have  established  a  procedure  for  trying  pattern-or-
practice cases that gives effect to these statutory require-
ments.  When the plaintiff seeks individual relief such as
reinstatement  or  backpay  after  establishing  a  pattern  or 
practice  of  discrimination,  “a  district  court  must  usually 
conduct additional proceedings . . . to determine the scope
of individual relief.”  Teamsters, 431 U. S., at 361.  At this 
phase, the burden of proof will shift to the company, but it 
will  have  the  right  to  raise  any  individual  affirmative 
defenses  it  may  have,  and  to  “demonstrate  that  the  indi-
vidual  applicant  was  denied  an  employment  opportunity 
for lawful reasons.”  Id., at 362. 

The  Court  of  Appeals  believed  that  it  was  possible  to 
replace such proceedings with Trial by Formula.  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.  The  percentage  of  claims  determined  to  be  valid 
would  then  be  applied  to  the  entire  remaining  class,  and
the  number  of  (presumptively)  valid  claims  thus  derived
would be multiplied by the average backpay award in the 
sample set to arrive at the entire class recovery—without 
further individualized proceedings.  603 F. 3d, at 625–627. 
We  disapprove  that  novel  project.    Because  the  Rules 
Enabling  Act  forbids  interpreting  Rule  23  to  “abridge,
enlarge  or  modify  any  substantive  right,”  28  U. S. C.
§2072(b);  see  Ortiz,  527  U. S.,  at  845,  a  class  cannot  be 
certified on the premise that Wal-Mart will not be entitled 
to litigate its statutory defenses to individual claims.  And 
because  the  necessity  of  that  litigation  will  prevent  back-
pay  from  being  “incidental”  to  the  classwide  injunction,
respondents’  class  could  not  be  certified  even  assuming,
monetary  relief  can  be 
arguendo,  that  “incidental” 
awarded to a 23(b)(2) class. 

The judgment of the Court of Appeals is 

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Reversed.