Document ID: ./input/supremecourt_opinions/opinions/23pdf/23a349_0813.pdf
Page Number: 39

Cite as:  603 U. S. ____ (2024) 

17 

BARRETT, J., dissenting 

36741.    Importantly,  implementing  the  FIP  “in  fewer  up-
wind states does not (and cannot possibly) result in overcon-
trol” given that “there was no overcontrol even when more 
states,  making  more  emission  reductions,  were  included.”  
Denial 22.  So the fact that EPA used state-specific data in 
its overcontrol analysis does not mean that the FIP’s emis-
sions limits depended on the number of States it covered.  
And the inclusion of fewer States in that analysis logically 
could not have affected the results. 
  Thus,  EPA  generally  characterized  the  FIP’s  emissions 
limits as dependent on nationwide data, not on any partic-
ular set of States.9  Confirming this interpretation, the final 
rule  contemplates  its  application to  a  different  number  of 
States.    It  recognizes  that  “states  may  replace  FIPs  with 
SIPs if EPA approves them,” and several sections explain 
how States may exit this FIP.  88 Fed. Reg. 36753, 36838–
36843.  And the rule’s severability provision explains that 
EPA  views  the  plan  as  “severable  along  . . .  state  and/or 
tribal jurisdictional lines.”  Id., at 36693. 
  Moreover,  EPA  justified  the  FIP’s  severability:  EPA 
“must address good neighbor obligations as expeditiously as 
practicable and by no later than the next applicable attain-
ment  date”;  severability  serves  “important  public  health 
and environmental benefits” and ensures that stakeholders 
can “rely on this final rule in their planning.”  Ibid.  These 

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9 The Court argues that EPA equated the framework it used here with 
the one that we described in EME Homer City.  Ante, at 18, and n. 13.  
But  even  if  EME  described  an  approach  that  selected  cost  thresholds 
“only after” conducting downwind air-quality assessments, ibid., it is not 
clear that the Good Neighbor Plan adopted this aspect of the EME frame-
work.    In  fact,  there  are  other  key  similarities  between  this  FIP  and 
EME’s approach.  For example, the final FIP refers to EME in order to 
note that EPA’s “uniform framework of policy judgments”—i.e., applying 
the same cost thresholds with “[n]ationwide consistency”—was upheld in 
that case.  88 Fed. Reg. 36673.  And the final FIP identifies cost thresh-
olds that EPA chose based on nationwide data—like $1,800 based on the 
cost of EGUs “optimiz[ing] . . . existing SCRs and SNCRs.”  Id., at 36749.