Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-451_7m58.pdf
Page Number: 90

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

9 

KAGAN, J., dissenting 

For one, because agencies often know things about a stat-
ute’s subject matter that courts could not hope to.  The point 
is  especially  stark  when  the  statute  is  of  a  “scientific  or 
technical nature.”  Kisor, 588 U. S., at 571 (plurality opin-
ion).  Agencies  are  staffed  with  “experts  in  the  field”  who 
can bring their training and knowledge to bear on open stat-
utory questions.  Chevron, 467 U. S., at 865.  Consider, for 
example, the first bulleted case above.  When does an alpha
amino acid polymer qualify as a “protein”?  See supra, at 5.  
I don’t know many judges who would feel confident resolv-
ing  that  issue. 
(First  question:  What  even  is  an  alpha
amino acid polymer?)  But the FDA likely has scores of sci-
entists on staff who can think intelligently about it, maybe 
collaborate with each other on its finer points, and arrive at
a  sensible  answer.  Or  take  the  perhaps  more  accessible-
sounding  second  case,  involving  the  Endangered  Species
Act.  See supra, at 5–6.  Deciding when one squirrel popu-
lation is “distinct” from another (and thus warrants protec-
tion) requires knowing about species more than it does con-
sulting a dictionary.  How much variation of what kind— 
geographic,  genetic,  morphological,  or  behavioral—should 
be  required?  A  court  could,  if  forced  to,  muddle  through
that  issue  and  announce  a  result.  But  wouldn’t  the  Fish 
and Wildlife Service, with all its specialized expertise, do a 
better job of the task—of saying what, in the context of spe-
cies protection, the open-ended term “distinct” means?  One 
idea  behind  the  Chevron  presumption  is  that  Congress— 

—————— 
clearly states that it is.”  Boechler v. Commissioner, 596 U. S. 199, 203 
(2022).  I could continue, except that this footnote is long enough.  The 
Chevron  deference  rule  is  to  the  same  effect:  The  Court  generally  as-
sumes that Congress intends to confer discretion on agencies to handle
statutory ambiguities or gaps, absent a direction to the contrary.  The 
majority calls that presumption a “fiction,” ante, at 26, but it is no more 
so than any of the presumptions listed above.  They all are best guesses—
and usually quite good guesses—by courts about congressional intent.