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Page Number: 33

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ARIZONA v. NAVAJO NATION 

GORSUCH, J., dissenting 

ask  the  United  States  to  fulfill  part  of  that  duty  by  as-
sessing what water  rights it holds for them.  The govern-
ment owes the Tribe at least that much. 

A 

Begin  with  the  governing  legal  principles.    Under  our 
Constitution, “all Treaties made” are “the supreme Law of
the Land.”  Art. VI, cl. 2.  Congress can pass laws to imple-
ment  those  treaties,  see,  e.g.,  Bond  v.  United  States,  572 
U. S.  844,  851,  855  (2014),  and  the  Executive  Branch  can 
act  in  accordance  with  them,  see,  e.g.,  Fok  Yung  Yo  v. 
United States, 185 U. S. 296, 303 (1902).  But the Judiciary 
also  has  an  important  role  to  play.    The  Constitution  ex-
tends  “[t]he  judicial  Power”  to  cases  “arising  under  . . . 
Treaties made, or which shall be made.”  Art. III, §2, cl. 1. 
As a result, this Court has recognized that Tribes may sue
to enforce rights found in treaties.  See Moe v. Confederated 
Salish  and  Kootenai  Tribes  of  Flathead  Reservation,  425 
U. S. 463, 472–477 (1976).  Other branches share the same 
understanding.  In enacting the Indian Trust Asset Reform 
Act  of  2016,  Congress  confirmed  its  belief  that  “commit-
ments made through written treaties” with the Tribes “es-
tablished enduring and enforceable Federal obligations” to 
them.  25 U. S. C. §5601(4)–(5) (emphasis added).  The Ex-
ecutive  Branch  has  likewise  and  repeatedly  advanced  the
position—including  in  this  very  litigation—that  “a  treaty
can be the basis of a breach-of-trust claim” enforceable in 
federal court.  Brief for Federal Parties 22–23, n. 5. 

What rights does a treaty secure?  A treaty is “essentially 
a contract between two sovereign nations.”  Washington v. 
Washington  State  Commercial  Passenger  Fishing  Vessel 
Assn., 443 U. S. 658, 675 (1979).  So a treaty’s interpreta-
tion, like “a contract’s interpretation, [is] a matter of deter-
mining  the  parties’  intent.”  BG  Group  plc  v.  Republic  of 
Argentina, 572 U. S. 25, 37 (2014).  That means courts must 
look to the “shared expectations of the contracting parties.”