Document ID: ./input/supremecourt_opinions/opinions/23pdf/23a349_0813.pdf
Page Number: 21.0

18 

OHIO v. EPA 

Opinion of the Court 

19.  Then, coming at the same point from another direction, 
the dissent seeks to excuse the agency’s lack of a reasoned 
reply as “harmless” given, again, “the apparent lack of con-
nection between the number of States covered and the FIP’s 
methodology.”  Post, at 20. 
  The  trouble  is,  if  the  government  had  arguments  along 
these lines, it did not make them.  It did not despite its am-
ple  resources  and  voluminous  briefing.    See  supra,  at  9.  
This  Court  “normally  decline[s]  to  entertain”  arguments 
“forfeited” by the parties.  Kingdomware Technologies, Inc. 
v. United States, 579 U. S. 162, 173 (2016).  And we see no 
persuasive reason to depart from that rule here. 
  If anything, we see one reason for caution after another.  
Start with the fact the dissent itself expresses little confi-
dence in its own theories, contending no more than it “ap-
pear[s]” EPA’s methodology did not depend on the number 
of covered States.  Post, at 14 (emphasis added).  Add to that 
the  fact  that,  at  oral  argument,  even  the  government  re-
fused to  say with  certainty  that  EPA  would  have  reached 
the  same  conclusions  regardless  of  which  States  were  in-
cluded in the FIP.  See Tr. of Oral Arg. 59.  Combine all that 
with the further fact that, in developing the FIP, EPA said 
it  used  the  “same  regulatory  framework”  this  Court  de-
scribed in EME Homer City Generation, L. P. v. EPA, 572 
U. S.  489.    E.g.,  EPA  Response  7–8.    And,  at  least  as  the 
Court described that framework, state-level analyses play 
a  significant  role  in  EPA’s  work.13    Finally,  observe  that, 
while the Act seems to anticipate, as the dissent suggests, 

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13 The  agency,  we  said,  “first  calculated,  for  each  upwind  State,  the 
quantity of emissions  the  State  could  eliminate  at  each of  several  cost 
[levels]”; next, it “conducted complex modeling to establish the combined 
effect of the upwind reductions projected at each cost [level] would have 
on air quality in downwind States”; and only after all that did the agency 
“then  identif[y]  significant  cost  [levels]”  to  use  in  setting  its  emissions 
budgets.  EME Homer City, 572 U. S., at 501–502.