Document ID: ./input/supremecourt_opinions/opinions/05pdf/05-130.pdf
Page Number: 3.0

Cite as:  547 U. S. ____ (2006) 

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 

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No. 05–130 
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EBAY INC., ET AL., PETITIONERS v.

MERCEXCHANGE, L. L. C. 

ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

APPEALS FOR THE FEDERAL CIRCUIT

[May 15, 2006] 

JUSTICE THOMAS delivered the opinion of the Court. 
Ordinarily, a federal court considering whether to award
permanent  injunctive  relief  to  a  prevailing  plaintiff  ap-
plies the four-factor test historically employed by courts of 
equity.  Petitioners  eBay  Inc.  and  Half.com,  Inc.,  argue
that this traditional test applies to disputes arising under 
the  Patent  Act.  We  agree  and,  accordingly,  vacate  the
judgment of the Court of Appeals. 

I 
Petitioner  eBay  operates  a  popular  Internet  Web  site
that  allows  private  sellers  to  list  goods  they  wish  to  sell,
either  through  an  auction  or  at  a  fixed  price.  Petitioner 
Half.com,  now  a  wholly  owned  subsidiary  of  eBay,  oper-
ates  a  similar  Web  site.    Respondent  MercExchange,
L. L. C.,  holds  a  number  of  patents,  including  a  business
method patent for an electronic market designed to facili-
tate  the  sale  of  goods  between  private  individuals  by 
establishing  a  central  authority  to  promote  trust  among 
participants.  See  U. S.  Patent  No.  5,845,265.    MercEx-
change sought to license its patent to eBay and Half.com, 
as  it  had  previously  done  with  other  companies,  but  the