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Page Number: 13.0

10 

ARIZONA v. NAVAJO NATION 

Opinion of the Court 

needed water. 

Of  course,  it  is  not  surprising  that  a  treaty  ratified  in 
1868  did  not  envision  and  provide  for  all  of  the  Navajos’ 
current  water  needs  155  years  later,  in  2023.  Under  the 
Constitution’s  separation  of  powers,  Congress  and  the 
President  may  update  the  law  to  meet  modern  policy 
priorities  and  needs.  To  that  end,  Congress  may  enact—
and  often  has  enacted—legislation  to  address  the  modern
water  needs  of  Americans,  including  the  Navajos,  in  the 
West.  Indeed, Congress has authorized billions of dollars
for  water  infrastructure  for  the  Navajos.    See,  e.g.,  Tr.  of 
Oral  Arg.  5,  11;  Consolidated  Appropriations  Act,  2021,
Pub. L. 116–260, 134 Stat. 3230.2 

But it is not the Judiciary’s role to update the law.  And 
on this issue, it is particularly important that federal courts
not  do  so.  Allocating  water  in  the  arid  regions  of  the 
American West is often a zero-sum situation.  See Brief for 
Western  Water  Users  and  Trade  Associations  as  Amici 
Curiae 13–14, 18–21.  And the zero-sum reality of water in
the West underscores that courts must stay in their proper
constitutional lane and interpret the law (here, the treaty) 
according  to  its  text  and  history,  leaving  to Congress  and 
the  President  the  responsibility  to  enact  appropriations
laws and to otherwise update federal law as they see fit in 
light of the competing contemporary needs for water. 

III 
The  Navajo  Tribe  advances  several  other  arguments  in
support of its claim that the 1868 treaty requires the United
States  to  take  affirmative  steps  to  secure  water  for  the 

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2 In this Court, the Navajos also briefly point to the 1849 treaty.  But 
that treaty did not grant the Navajos a reservation.  In that treaty, the
United States agreed to “designate, settle, and adjust” the boundaries of 
the Navajo territory at some future point.  9 Stat. 975.  No provision of 
the 1849 treaty obligated the United States to take affirmative steps to 
secure water for the Navajos.