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2 

PEREZ v. MORTGAGE BANKERS ASSN. 

THOMAS, J., concurring in judgment 

utive agency, it raises constitutional concerns.  This line of 
precedents undermines our obligation to provide a judicial
check  on  the  other  branches,  and  it  subjects  regulated 
parties to precisely the abuses that the Framers sought to 
prevent. 

I 
The  doctrine  of  deference  to  an  agency’s  interpretation
of  regulations  is  usually  traced  back  to  this  Court’s  deci-
sion in Seminole Rock, supra, which involved the interpre-
tation  of  a  war-time  price  control  regulation,  id.,  at  411. 
Along with a general price freeze, the Administrator of the 
Office  of  Price  Administration  had  promulgated  special-
ized  regulations  governing  the  maximum  price  for  differ-
ent  commodities.  Id.,  at  413.  When  the  Administrator 
brought  an  enforcement  action  against  a  manufacturer  of 
crushed stone, the manufacturer  challenged the Adminis-
trator’s interpretation of his regulations. 

The  lower  courts  agreed  with  the  manufacturer’s  inter-
pretation,  id.,  at  412–413,  but  this  Court  reversed.    In 
setting  out  the  approach  it  would  apply  to  the  case,  the 
Court  announced—without  citation  or  explanation—that 
an  administrative  interpretation  of  an  ambiguous  regula-
tion was entitled to “controlling weight”: 

“Since  this  involves  an  interpretation  of  an  adminis-
trative regulation a court must necessarily look to the
administrative  construction  of  the  regulation  if  the 
meaning of the words used is in doubt.  The intention 
of  Congress  or  the  principles  of  the  Constitution  in 
some  situations  may  be  relevant  in  the  first  instance
in  choosing  between  various  constructions.  But  the 
ultimate  criterion  is  the  administrative  interpreta-
tion,  which  becomes  of  controlling  weight  unless  it  is
plainly erroneous or inconsistent with the regulation.” 
Id., at 413–414.