Document ID: ./input/supremecourt_opinions/opinions/23pdf/23a349_0813.pdf
Page Number: 18.0

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

15 

Opinion of the Court 

  Second, the government pivots in nearly the opposite di-
rection.  Now, it says, if its final rule lacks a reasoned re-
sponse to the applicants’ concern, it is because no one raised 
that concern during the public comment period.  And, the 
agency stresses, a litigant may pursue in court only claims 
premised on objections first “ ‘raised with reasonable speci-
ficity’ ” before the agency during the public comment period.  
Id.,  at  19–20  (quoting  §7607(d)(7)(B));  see  also post,  at  8–
11. 
  We  cannot  agree.    The  Act’s  “reasonable  specificity”  re-
quirement does not call for “a hair-splitting approach.”  Ap-
palachian  Power  Co.  v.  EPA,  135  F. 3d  791,  817  (CADC 
1998).  A party need not “rehears[e]” the identical argument 
made before the agency; it need only confirm that the gov-
ernment  had  “notice  of  [the]  challenge”  during  the  public 
comment period and a chance to consider “in substance, if 
not in form, the same objection now raised” in court.  Id., at 
818; see also, e.g., Bahr v. Regan, 6 F. 4th 1059, 1070 (CA9 
2021). 
  Here, EPA had notice of the objection the applicants seek 
to  press  in  court.    Commenters  alerted  the  agency  that, 
should  some  States  no  longer  participate  in  the  plan,  the 
agency would need to return to the drawing board and “con-
duct a new assessment and modeling of contribution” to de-
termine  what  emissions-control  measures  maximized  cost 
effectiveness  in  securing  downwind  ozone  air-quality  im-
provements.    Comments  of  Air  Stewardship  Coalition,  at 
13–14; see also Part I–C, supra (noting examples of other 

—————— 
such promulgation”), 7607(d)(7)(A) (restricting the “record for judicial re-
view”).  We therefore look to only “the grounds that the agency invoked 
when  it”  promulgated  the  FIP.    Michigan  v.  EPA,  576  U. S.  743,  758 
(2015).  Should the applicants show the FIP was arbitrary or capricious 
on the existing record, as we have concluded is likely, the Clean Air Act 
entitles  them  to  “revers[al]”  of  that  rule’s  mandates  on  them.  
§7607(d)(9)(A).