Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-1530_n758.pdf
Page Number: 86

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WEST VIRGINIA v. EPA 

KAGAN, J., dissenting 

and  continues  to  do  so—including  on  important  policy  is-
sues.  As this Court has recognized, it is often “unreasona-
ble  and  impracticable”  for  Congress  to  do  anything  else. 
American  Power  &  Light  Co.  v.  SEC,  329  U. S.  90,  105 
(1946).  In all times, but ever more in “our increasingly com-
plex society,” the Legislature “simply cannot do its job ab-
sent an ability to delegate power under broad general direc-
tives.”  Mistretta v. United States, 488 U. S. 361, 372 (1989). 
Consider just two reasons why.

First,  Members  of  Congress  often  don’t  know  enough—
and know they don’t know enough—to regulate sensibly on 
an issue.  Of course, Members can and do provide overall 
direction.  But then they rely, as all of us rely in our daily
lives,  on  people  with  greater  expertise  and  experience. 
Those people are found in agencies.  Congress looks to them
to make specific judgments about how to achieve its more
general objectives.  And it does so especially, though by no
means exclusively, when an issue has a scientific or tech-
nical dimension.  Why wouldn’t Congress instruct EPA to
select “the best system of emission reduction,” rather than
try to choose that system itself?  Congress knows that sys-
tems of emission reduction lie not in its own but in EPA’s 
“unique  expertise.”    Martin  v.  Occupational  Safety  and 
Health Review Comm’n, 499 U. S. 144, 151 (1991).

Second  and  relatedly,  Members  of  Congress  often  can’t 
know enough—and again, know they can’t—to keep regula-
tory schemes working across time.  Congress usually can’t
predict  the  future—can’t  anticipate  changing  circum-
stances and the way they will affect varied regulatory tech-
niques.  Nor can Congress (realistically) keep track of and
respond to fast-flowing developments as they occur.  Once 
again, that is most obviously true when it comes to scientific
and technical matters.  The “best system of emission reduc-
tion” is not today what it was yesterday, and will surely be 
something different tomorrow.  So for this reason too, a ra-
tional  Congress  delegates.  It  enables  an  agency  to  adapt