Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-1454_5h26.pdf
Page Number: 43

Cite as:  585 U. S. ____ (2018) 

19 

BREYER, J., dissenting 

ties  are  presumptively  in  the  same  market,”  even  if  they
are  not  “close  substitutes  for  each  other  on  the  demand 
side.”  Ibid.  That is because a firm that produces one such
product  can,  in  response  to  a  price  increase  in  the  other, 
easily  shift  its  production  and  thereby  limit  its  compet- 
itor’s  power  to  impose  the  higher  price.    See  id.,  ¶561a,
at 379. 

Unlike  the  various  types  of  central  station  services  at
issue in Grinnell Corp., however, the shopper-related and
merchant-related services that American Express provides 
are  not  “producer  substitutes”  any  more  than  they  are 
traditional  substitutes.  For  producers  as  for  consumers,
the services are instead complements.  Credit card compa­
nies  must  sell  them  together  for  them  to  be  useful.    As  a 
result,  the  credit-card  companies  cannot  respond  to,  say, 
merchant-related  price  increases  by  shifting  production
away  from  shopper-related  services  to  merchant-related 
services.  The  relevant  “commercial  realities”  in  this  case 
are thus completely different from those in Grinnell Corp. 
(The majority also cites Brown Shoe Co. v. United States, 
370  U. S.  294,  336–337  (1962),  for  this  point,  but  the 
“commercial  realities”  considered  in  that  case  were  that 
“shoe  stores  in  the  outskirts  of  cities  compete  effectively
with  stores  in  central  downtown  areas,”  and  thus  are 
part  of  the  same  market.    Id.,  at  338–339.  Here, 
merchant-related  services  do  not, as  I  have  said,  compete 
with shopper-related services, and so Brown Shoe Co. does 
not  support  the  majority’s  position.)  Thus,  our  precedent
provides  no  support  for  the  majority’s  special  approach
to  defining  markets  involving  “two-sided  transaction
platforms.” 

3 
What  about  the  academic  articles  the  majority  cites?
The  first  thing  to  note  is  that  the  majority  defines  “two-
sided transaction platforms” much more broadly than the