Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-376_7l48.pdf
Page Number: 19.0

Cite as:  599 U. S. ____ (2023) 

11 

Opinion of the Court 

the  Indian  tribes,  and  such  power  is  superior  and  para-
mount to the authority of any State within whose limits are 
Indian tribes”).

To be clear, however, “plenary” does not mean “free-float-
ing.”  A power unmoored from the Constitution would lack 
both justification and limits.  So like the rest of its legisla-
tive powers, Congress’s authority to regulate Indians must 
derive  from  the  Constitution,  not  the  atmosphere.    Our 
precedent traces that power to multiple sources. 

The Indian Commerce Clause authorizes Congress “[t]o
regulate Commerce . . . with the Indian Tribes.”  Art. I, §8, 
cl. 3.  We have interpreted the Indian Commerce Clause to
reach not only trade, but certain “Indian affairs” too.  Cot-
ton  Petroleum  Corp.  v.  New  Mexico,  490  U. S.  163,  192 
(1989).  Notably, we have declined to treat the Indian Com-
merce Clause as interchangeable with the Interstate Com-
merce Clause.  Ibid.  While under the Interstate Commerce 
Clause, States retain “some authority” over trade, we have
explained  that  “virtually  all  authority  over  Indian  com-
merce and Indian tribes” lies with the Federal Government. 
Seminole Tribe of Fla. v. Florida, 517 U. S. 44, 62 (1996). 

The  Treaty  Clause—which  provides  that  the  President
“shall have Power, by and with the Advice and Consent of
the Senate, to make Treaties”—provides a second source of
power over Indian affairs.  Art. II, §2, cl. 2.  Until the late 
19th  century,  relations  between  the  Federal  Government
and  the  Indian  tribes  were  governed  largely  by  treaties. 
Lara, 541 U. S., at 201.  Of course, the treaty power “does 
not literally authorize Congress to act legislatively,” since
it is housed in Article II rather than Article I.  Ibid.  Never-
theless, we have asserted that “treaties made pursuant to 
that  power  can  authorize  Congress  to  deal  with  ‘matters’ 
with which otherwise ‘Congress could not deal.’ ”  Ibid.  And 
even though the United States formally ended the practice 
of entering into new treaties with the Indian tribes in 1871,
this decision did not limit Congress’s power “to legislate on