Document ID: ./input/supremecourt_opinions/opinions/19pdf/19-715_febh.pdf
Page Number: 41.0

16 

TRUMP v. MAZARS USA, LLP 

THOMAS, J., dissenting

  The Court acknowledged Kilbourn, but erroneously dis-
tinguished its discussion regarding the constitutionality of 
legislative subpoenas as immaterial dicta.  McGrain, supra, 
at  170–171  (quoting  Kilbourn,  supra,  at  189).    The  Court 
concluded that “the two houses of Congress, in their sepa-
rate  relations,  possess  not  only  such  powers  as  are  ex-
pressly granted to them by the Constitution, but such aux-
iliary powers as are necessary and appropriate to make the 
express powers effective.”  McGrain, supra, at 173. 

Instead of relying on Kilbourn’s analysis, McGrain devel-
oped a test that rested heavily on functional considerations.
The Court wrote that “[a] legislative body cannot legislate 
wisely or effectively in the absence of information respect-
ing the conditions which the legislation is intended to affect 
or change.”  273 U. S., at 175.  Because “mere requests for
such information often are unavailing, and also that infor-
mation which is volunteered is not always accurate or com-
plete,”  “some  means  of compulsion  are  essential  to  obtain 
what is needed.”  Ibid. 

The Court thus concluded that Congress could issue leg-
islative subpoenas, provided that “the purpose for which the 
witness’s testimony was sought was to obtain information 
in aid of the legislative function.”  Id., at 176.  The Court 
has since applied this test to subpoenas for papers without 
any further analysis of the text or history of the Constitu-
tion.  See Eastland v. United States Servicemen’s Fund, 421 
U. S.  491,  504–505  (1975).  The  majority  today  modifies 
that test for cases involving the President, but it leaves the
core of the power untouched.  Ante, at 18–20. 

2 
The opinion in McGrain lacks any foundation in text or
history  with  respect  to  subpoenas  for  private,  nonofficial
documents.  It fails to recognize that Congress, unlike Par-
liament, is not supreme.  It does not cite any specific prece-