Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-1496_d18f.pdf
Page Number: 1.0

(Slip Opinion) 

OCTOBER  TERM,  2022 

1 

Syllabus 

NOTE:  Where  it  is  feasible,  a  syllabus  (headnote)  will  be  released,  as  is 
being  done  in  connection  with  this  case,  at  the  time  the  opinion  is  issued. 
The  syllabus  constitutes  no  part  of  the  opinion  of  the  Court  but  has  been 
prepared  by  the  Reporter  of  Decisions  for  the  convenience  of  the  reader. 
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. 

SUPREME COURT OF THE UNITED STATES 

Syllabus 

TWITTER, INC. v. TAAMNEH ET AL. 

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR 
THE NINTH CIRCUIT 

No. 21–1496.  Argued February 22, 2023—Decided May 18, 2023 

In  2017,  Abdulkadir  Masharipov  carried  out  a  terrorist  attack  on  the 
Reina nightclub in Istanbul, Turkey, on behalf of the Islamic State of 
Iraq  and  Syria  (ISIS),  a  designated  Foreign  Terrorist  Organization. 
Masharipov  killed  Nawras  Alassaf  and  38  others.    Alassaf’s  family 
then brought this suit under 18 U. S. C. §2333, an Antiterrorism Act
(ATA) provision that permits U. S. nationals who have been “injured 
. . . by reason of an act of international terrorism” to file a civil suit for
damages.  Instead of suing ISIS directly under §2333(a), the plaintiffs
(respondents here) invoked §2333(d)(2) to sue three of the largest so-
cial-media  companies  in  the  world—Facebook,  Twitter  (petitioner 
here),  and  Google  (which  owns  YouTube)—for  aiding  and  abetting 
ISIS. 

The parties today agree on the basic aspects of these platforms: Bil-
lions  of  people  from  around  the  world  have  signed  up  for  them  and 
upload massive amounts of content each day.  Defendants profit from
that content by placing advertisements on or near it and use “recom-
mendation” algorithms that match content, advertisements, and users 
based on information about the use, advertisement, and content being
viewed.  As the parties represent things, the algorithms here match 
any content with any user who is more likely to view that content, and
the platforms perform little to no front-end screening on any content 
before it is uploaded.

Plaintiffs, however, allege that for several years the companies have 
knowingly allowed ISIS and its supporters to use their platforms and
“recommendation” algorithms as tools for recruiting, fundraising, and 
spreading propaganda; plaintiffs further allege that these companies
have, in the process, profited from the advertisements placed on ISIS’ 
tweets, posts, and videos.  The District Court dismissed the complaint