Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-1454_5h26.pdf
Page Number: 19.0

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

15 

Opinion of the Court 

475 U. S. 574, 594 (1986) (“ ‘[W]e must be concerned lest a 
rule or precedent that authorizes a search for a particular
type of undesirable pricing behavior end up by discourag-
ing  legitimate  price  competition’ ”);  Leegin,  551  U. S.,  at 
895 (noting that courts should avoid “increas[ing] the total 
cost of the antitrust system by prohibiting procompetitive
conduct the antitrust laws should encourage”).  Accordingly,
we  will  analyze  the  two-sided  market  for  credit-card
transactions  as  a  whole  to  determine  whether  the  plain-
tiffs have shown that Amex’s antisteering provisions have
anticompetitive effects. 

B 
The  plaintiffs  have  not  carried  their  burden  to  prove
anticompetitive effects in the relevant market.  The plain-
tiffs stake their entire case on proving that Amex’s agree-
ments  increase  merchant  fees.    We  find  this  argument 
unpersuasive.

As  an  initial  matter,  the  plaintiffs’  argument  about 
merchant fees wrongly focuses on only one side of the two-
sided  credit-card  market.    As  explained,  the  credit-card
market  must  be  defined  to  include  both  merchants  and 
cardholders.  Focusing on merchant fees alone misses the 
mark  because  the  product  that  credit-card  companies  sell 
is transactions, not services to merchants, and the compet-
itive effects of a restraint on transactions cannot be judged
by  looking  at  merchants  alone.    Evidence  of  a  price  in-
crease  on  one  side  of  a  two-sided  transaction  platform 
cannot by itself demonstrate an anticompetitive exercise of 
market power.  To demonstrate anticompetitive effects on 
the two-sided credit-card market as a whole, the plaintiffs 
must  prove  that  Amex’s  antisteering  provisions  increased 
the  cost  of  credit-card  transactions  above  a  competitive 
level,  reduced  the  number  of  credit-card  transactions,  or 
otherwise  stifled  competition  in  the  credit-card  market.
See  1  Kalinowski  §12.02[2];  Craftsman  Limousine,  Inc.,