Document ID: ./input/supremecourt_opinions/opinions/20pdf/20-197_5ie6.pdf
Page Number: 1.0

Cite as:  593 U. S. ____ (2021) 

1 

THOMAS, J., concurring 

SUPREME COURT OF THE UNITED STATES 

JOSEPH R. BIDEN, JR., PRESIDENT OF THE UNITED 
STATES, ET AL. v. KNIGHT FIRST AMENDMENT 
INSTITUTE AT COLUMBIA UNIVERSITY, ET AL. 

ON PETITION FOR WRIT OF CERTIORARI TO THE UNITED 
STATES COURT OF APPEALS FOR THE SECOND CIRCUIT 

No. 20–197.  Decided April 5, 2021 

The petition for a writ of certiorari is granted.  The judg-
ment  is  vacated,  and  the  case  is  remanded  to  the  United 
States Court of Appeals for the Second Circuit with instruc-
tions to dismiss the case as moot.  See United States v. Mun-
singwear, Inc., 340 U. S. 36 (1950). 
JUSTICE THOMAS, concurring. 
When a person publishes a message on the social media 
platform Twitter, the platform by default enables others to
republish (retweet) the message or respond (reply) to it or
other  replies  in  a  designated  comment  thread.    The  user 
who generates the original message can manually “block”
others from republishing or responding.

Donald  Trump,  then  President  of  the  United  States, 
blocked several users from interacting with his Twitter ac-
count.  They sued.  The Second Circuit held that the com-
ment  threads  were  a  “public  forum”  and  that  then-Presi-
dent  Trump  violated  the  First  Amendment  by  using  his
control  of  the  Twitter  account  to  block  the  plaintiffs  from
accessing the comment threads.  Knight First Amdt. Inst. at 
Columbia Univ. v. Trump, 928 F. 3d 226 (2019).  But Mr. 
Trump,  it  turned  out,  had  only  limited  control  of  the  ac-
count; Twitter has permanently removed the account from
the platform.

Because of the change in Presidential administration, the 
Court correctly vacates the Second Circuit’s decision.  See 
United States v. Munsingwear, Inc., 340 U. S. 36 (1950).  I