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Page Number: 22.0

16 

MASSACHUSETTS v. EPA 

Opinion of the Court 

century  ago,  so  too  does  Massachusetts’  well-founded 
desire to preserve its sovereign territory today.  Cf. Alden 
v. Maine, 527 U. S. 706, 715 (1999) (observing that in the 
federal system, the States “are not relegated to the role of
mere  provinces  or  political  corporations,  but  retain  the 
dignity,  though  not  the  full  authority,  of  sovereignty”).
That  Massachusetts  does  in  fact  own  a  great  deal  of  the
“territory  alleged  to  be  affected”  only  reinforces  the  con-
clusion  that  its  stake  in  the  outcome  of  this  case  is  suffi-
ciently concrete to warrant the exercise of federal judicial 
power.

When  a  State  enters  the  Union,  it  surrenders  certain 
sovereign  prerogatives.    Massachusetts  cannot  invade 
Rhode  Island  to  force  reductions  in  greenhouse  gas  emis-
sions,  it  cannot  negotiate  an  emissions  treaty  with  China
or  India,  and  in  some  circumstances  the  exercise  of  its 
police  powers  to  reduce  in-state  motor-vehicle  emissions 
might  well  be  pre-empted.    See  Alfred  L.  Snapp  &  Son, 
Inc. v. Puerto Rico ex rel. Barez, 458 U. S. 592, 607 (1982) 
(“One  helpful  indication  in  determining  whether  an  al-
leged  injury  to  the  health  and  welfare  of  its  citizens  suf-
fices  to  give  the  State  standing  to  sue  parens  patriae  is 
whether the injury is one that the State, if it could, would 
likely attempt to address through its sovereign lawmaking 
powers”).

These  sovereign  prerogatives  are  now  lodged  in  the
Federal  Government,  and  Congress  has  ordered  EPA  to
protect Massachusetts (among others) by prescribing stan-
dards applicable to the “emission of any air pollutant from
any class or classes of new motor vehicle engines, which in
[the Administrator’s] judgment cause, or contribute to, air
pollution which may reasonably be anticipated to endanger
public  health  or  welfare.”    42  U. S. C.  §7521(a)(1).    Con-
gress  has  moreover  recognized  a  concomitant  procedural
right  to  challenge  the  rejection  of  its  rulemaking  petition
as  arbitrary  and  capricious.    §7607(b)(1).  Given  that  pro-