Document ID: ./input/supremecourt_opinions/opinions/06pdf/05-1120.pdf
Page Number: 37.0

Cite as:  549 U. S. ____ (2007) 

31 

Opinion of the Court 

EPA  has  refused  to  comply  with  this  clear  statutory
command.  Instead, it has offered a laundry list of reasons
not to regulate.  For example, EPA said that a number of 
voluntary  executive  branch  programs  already  provide  an 
effective response to the threat of global warming, 68 Fed. 
Reg.  52932,  that  regulating  greenhouse  gases  might  im-
pair the President’s ability to negotiate with “key develop-
ing  nations”  to  reduce  emissions,  id.,  at  52931,  and  that 
curtailing motor-vehicle emissions would reflect “an ineffi-
cient,  piecemeal  approach  to  address  the  climate  change 
issue,” ibid. 

Although we have neither the expertise nor the author-
ity  to  evaluate  these  policy  judgments,  it  is  evident  they
have  nothing  to  do  with  whether  greenhouse  gas  emis-
sions  contribute  to  climate  change.    Still  less  do  they
amount  to  a  reasoned justification  for  declining  to  form  a
scientific judgment.  In particular, while the President has
broad authority in foreign affairs, that authority does not 
extend  to  the  refusal  to  execute  domestic  laws.    In  the 
Global  Climate  Protection  Act  of  1987,  Congress  author-
ized the State Department—not EPA—to formulate United
States foreign  policy  with  reference to environmental mat-
ters relating to climate.  See §1103(c), 101 Stat. 1409.  EPA 
has  made  no  showing  that  it  issued  the  ruling  in  question
here  after  consultation  with  the  State  Department.    Con-
gress  did  direct  EPA  to  consult  with  other  agencies  in  the
formulation  of its policies and rules, but the State Depart-
ment is absent from that list.  §1103(b). 

Nor can EPA avoid its statutory obligation by noting the
uncertainty surrounding various features of climate change
and  concluding  that  it  would  therefore  be  better  not  to
regulate at this time.  See 68 Fed. Reg. 52930–52931.  If the 
scientific uncertainty is so profound that it precludes EPA 
from  making  a  reasoned  judgment  as  to  whether  green-
house  gases  contribute  to  global  warming,  EPA  must  say 
so.  That  EPA  would  prefer  not  to  regulate  greenhouse