Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-1530_n758.pdf
Page Number: 19

Cite as:  597 U. S. ____ (2022) 

13 

Opinion of the Court 

actions. 

The Court of Appeals consolidated all 12 petitions for re-
view into one case.  It then held that EPA’s “repeal of the 
Clean Power Plan rested critically on a mistaken reading of
the Clean Air Act”—namely, that generation shifting can-
not be a “system of emission reduction” under Section 111.
985 F. 3d, at 995.  To the contrary, the court concluded, the 
statute could reasonably be read to encompass generation 
shifting.  As part of that analysis, the Court of Appeals con-
cluded that the major questions doctrine did not apply, and 
thus rejected the need for a clear statement of congressional
intent  to  delegate  such  power  to  EPA.  Id.,  at  959–968. 
Having found that EPA misunderstood the scope of its au-
thority  under  the  Clean  Air  Act,  the  Court  vacated  the 
Agency’s repeal of the Clean Power Plan and remanded to 
the  Agency  for  further  consideration.   Id.,  at 995.    It  also  
vacated and remanded the replacement rule, the ACE Rule,
for the same reason.  Ibid. 

The court’s decision, handed down on January 19, 2021,
was quickly followed by another change in Presidential ad-
ministrations.  One month later, EPA moved the Court of 
Appeals to partially stay the issuance of its mandate as it 
pertained to the Clean Power Plan.  The Agency did so to
ensure that the Clean Power Plan would not immediately 
go back into effect.  Respondents’ Motion for a Partial Stay
of Issuance of the Mandate in American Lung Assn. v. EPA, 
No. 19–1140 etc. (CADC), p. 4.  EPA believed that such a 
result would not make sense while it was in the process of 
considering  whether  to  promulgate  a  new  Section  111(d) 
rule.  Ibid.  No party opposed the motion, and the court ac-
cordingly  stayed  its  vacatur  of  the  Agency’s  repeal  of  the 
Clean Power Plan. 

Westmoreland, NACC, and the States defending the re-
peal of the Clean Power Plan all filed petitions for certio-
rari.  We granted the petitions and consolidated the cases.
595 U. S. ___ (2021).