Document ID: ./input/supremecourt_opinions/opinions/23pdf/23a349_0813.pdf
Page Number: 20

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

17 

Opinion of the Court 

however, EPA had the basis of the applicants’ objection be-
fore it during the comment period.  It chose to respond with 
a severability provision that in no way grappled with their 
concern.  Nothing requires the applicants to return to EPA 
to raise (again) a concern EPA already had a chance to ad-
dress. 
  Taking  the  government’s  argument  (much)  further,  the 
dissent posits that every “objection that [a] final rule was 
not  reasonably  explained”  must  be  raised  in  a  motion  for 
reconsideration.  Post, at 7 (internal quotation marks omit-
ted; emphasis deleted).  But there is a reason why the gov-
ernment does  not  go  so  far.   The  Clean  Air  Act  opens the 
courthouse  doors  to  those  with  objections  the  agency  al-
ready ignored.  If an “objection [is] raised with reasonable 
specificity  during  the  period  for  public  comment”  but  not 
reasonably addressed in the final rule, the Act permits an 
immediate challenge.  §7607(d)(7)(B).  A person need not go 
back  to  the  agency  and  insist  on  an  explanation  a  second 
time.    Tellingly,  the  case  on  which  the  dissent  relies  in-
volves an entirely different situation:  a “ ‘logical outgrowth’ 
challeng[e].”  Post, at 7.  There, the objection was that EPA 
had  supposedly  “ ‘significantly  amend[ed]  the  [r]ule  be-
tween the proposed and final versions,’ ” making it impossi-
ble for people to comment on the rule during the comment 
period.  Ibid. (quoting EME Homer, 795 F. 3d, at 137).  That 
is nothing like the challenge here, where EPA failed to ad-
dress an important problem the public could and did raise 
during the comment period. 

B 
  With  the  government’s  theories  unavailing,  the  dissent 
advances others of its own.  It begins by suggesting that the 
problem the applicants raise was not “ ‘important’ ” enough 
to  warrant  a  reasoned  reply  from  the  agency  because  the 
methodology EPA employed in its FIP “appear[s] not to de-
pend on the number of covered States.”  Post, at 12–17, 18–