Twitter, Inc. v. Taamneh

LII note: The U.S. Supreme Court has now decided Twitter, Inc. v. Taamneh.


(1) Does a social media website that allegedly could have taken more meaningful action to prevent terrorists from using its services provide substantial assistance to those terrorists in violation of 18 U.S.C. § 2333; and (2) can a social media website incur liability for aiding and abetting under § 2333 despite a lack of connection between their generic, widely available services and the specific terrorist act that injured the plaintiff?

Oral argument: 
February 22, 2023

This case asks the Supreme Court to determine whether social media platforms such as Twitter, Facebook, and Google provide substantial assistance to terrorists by allegedly not taking meaningful action to prevent such terrorists from using their services. This case also asks the Supreme Court to determine whether the same social media platforms can be held liable under the Justice Against Sponsors of Terrorism Act (“JASTA”), even if their services were not used in connection with the specific act of terrorism that caused injury to the plaintiff. Twitter contends that a defendant does not knowingly provide substantial assistance through general awareness that terrorists were among its many users, and that liability cannot stem from such generalized assistance to a terrorist organization. Mehier Taamneh counters that whether Twitter and other defendants know of terrorist use of their services is a question of fact, and, at this stage, the Court need only decide that plaintiff’s factual allegation is plausible. Taamneh also argues that liability exists when a defendant substantially assists international terrorism and that JASTA’s text doesn’t limit liability to action that has a direct connection to the specific attack that injures the plaintiff.

Questions as Framed for the Court by the Parties 

(1) Whether a defendant that provides generic, widely available services to all its numerous users and “regularly” works to detect and prevent terrorists from using those services “knowingly” provided substantial assistance under 18 U.S.C. § 2333 merely because it allegedly could have taken more “meaningful” or “aggressive” action to prevent such use; and (2) whether a defendant whose generic, widely available services were not used in connection with the specific “act of international terrorism” that injured the plaintiff may be liable for aiding and abetting under Section 2333.


On January 1, 2017, Abdulkadir Masharipov, an individual affiliated with and trained by the Islamic State of Iraq and Syria (“ISIS”), committed a terrorist attack on the Reina nightclub in Istanbul, Turkey. Gonzalez v. Google, at 16. Masharipov fired more than 120 rounds into a crowd of 700 people for seven minutes, injuring 69 and killing 39. Id. at 17. Among the 39 people killed was Nawras Alassaf, a Jordanian citizen and relative of Respondents Mehier Taamneh, et al. (“Taamneh”), who are American citizens. Id. The day after the massacre, ISIS claimed responsibility for the killings. Id.

Twitter is a social networking platform where millions of users communicate with one another and share information publicly and globally. Id. Each day, Twitter publishes more than 500 million Tweets, or 5700 Tweets per second. Brief for Petitioner, Twitter, Inc. at 6. Twitter can review content reported by other users for violating its rules or conditions and remove tweets and accounts unilaterally. Gonzalez at 17. Such rules prohibit a user from threatening or promoting terrorism or using Twitter for any unlawful purposes or in furtherance of illegal activities. Brief for Petitioner at 6. Twitter has consistently terminated accounts associated with terrorist organizations or that violated its prohibitions on terrorism-related content. Id. at 7. Since 2015, Twitter has terminated over 1.7 million accounts relating to terrorist organizations. Id.

Taamneh alleges that Twitter has been aware of ISIS’s presence on Twitter and use of the platform to recruit and spread its propaganda globally. Brief for Respondent, Mehier Taamneh et al. at 3. In fact, there have been discussions between senior United States officials and large social media companies on initiatives to block terrorists on their websites more actively. Id. at 4.

The Anti-Terrorism Act (“ATA”), codified in 18 U.S.C. § 2333(a), allows United States nationals to recover damages for injuries suffered by international terrorism. Gonzalez, at 10. The Justice Against Sponsors of Terrorism Act (“JASTA”) modifies the ATA in § 2333(d) and provides for secondary liability for aiding and abetting, through either knowingly providing substantial assistance to international terrorists or conspiring with such persons. Id. at 10-11. Taamneh sued Twitter, Facebook, and Google (which owns YouTube) in the United States District Court for the Northern District of California, alleging a violation of § 2333(d). Id. at 17. Taamneh accused the social media companies of aiding and abetting ISIS by knowingly providing its members their services, which served as substantial assistance to terrorism. Id. at 10.

The court dismissed Taamneh’s case for failure to state a claim upon which relief can be granted under Federal Rule of Civil Procedure (“FRCP”) 12(b)(6), along with two other cases Gonzalez v. Google LLC and Clayborn v. Twitter, Inc. filed under the ATA against Twitter, Facebook, and Google on the basis that these companies allowed ISIS to post videos and share other content. Gonzalez at 4. Plaintiffs in these three cases, including Taamneh, appealed the district court’s ruling to the United States Court of Appeals for the Ninth Circuit. Id. The Ninth Circuit affirmed the district court’s dismissal of Gonzales and Clayborn but reversed and remanded for further proceedings in Taamneh. Id. at 12.

Twitter appealed the Ninth Circuit’s decision, and the United States Supreme Court granted certiorari on October 3, 2022.



Twitter argues that the Ninth Circuit wrongly interpreted the statutory language of JASTA. Brief for Petitioner, Twitter, Inc. at 24. Twitter claims that the plain statutory language of § 2333(d) of JASTA clearly provides secondary liability only when an individual assists in a specific act of terrorism, not the terrorist organization’s general campaign or general course of conduct. Id. Twitter observes that § 2333(d) repeats three times the phrase “an act of international terrorism,” which refers to the terrorist act giving rise to the claim. Id. Twitter reasons that if direct liability derives from a direct “act of international terrorism,” secondary liability should also derive from assistance provided for a relevant “act of international terrorism.” Id. Twitter continues that the dictionary definition of the word “abet” indicates that the secondary actor aids and abets a perpetrator in committing “a wrongdoing,” not in the perpetrator’s general course of conduct. Id.

Twitter also argues that statutory language reveals congressional intent to establish secondary liability for assistance with a specific act. Id. at 25. Twitter contends that prescribing the indefinite article “an” to “act of terrorism” provides evidence that Congress intended for the act, in this context, to be a discrete event or incident. Id. Twitter also contrasts the statutory language in § 2333(d) with that of § 2339B, which establishes liability for providing materials “to the terrorist organization.” Id. Twitter reasons that if Congress intended a broad application of § 2333(d), as Taamneh claims, it would have employed similarly broad language. Id.

Further, Twitter claims that since Taamneh has conceded that the “act of international terrorism” giving rise to Taamneh’s claim is the Reina attack and not ISIS’s general terrorist and extremist campaigns, an aider with secondary liability must have assisted in the Reina attack specifically. Id. at 24. Therefore, Twitter argues that JASTA requires Twitter to know the specific user accounts that substantially assisted in the Reina attack. Id. at 36. Twitter emphasizes that Taamneh did not allege the existence of such accounts nor that permitting them platform access substantially assisted in the Reina attack. Id.

Taamneh counters that the Ninth Circuit correctly interpreted § 2333(d) of JASTA and applied the rules the United States Court of Appeals for the District of Columbia Circuit set forth in Halberstam v. Welch. Brief for Respondent, Taamneh et al. at 17. Taamneh argues that JASTA prescribes secondary liability to a defendant who assists with the general campaign of a terrorist organization. Id. at 16. Taamneh contends that the plain text of § 2333(d) reveals that the object of the verbs “aid” and “abet” is properly understood as a “person who committed such an act of international terrorism,” not the specific “act of international terrorism.” Id. at 34. Therefore, Taamneh argues that under JASTA, Twitter is liable for secondary liability even if it did not assist in the specific act alone, but merely assisted the individuals who committed the terrorism. Id. Taamneh contends that the statutory language does not limit whom a defendant should have assisted and abetted to incur liability. Id. Specifically, Taamneh argues, the statute does not include the word “to” after “substantial assistance,” which would support Twitter’s argument that a liable defendant must have provided assistance to the perpetrator of a specific terrorist act. Id.

Taamneh also argues that Congress intentionally omitted such significant indicators for JASTA to be broadly construed. Id. at 35. Taamneh reasons that Twitter’s exceptionally narrow interpretation of the statute renders JASTA less meaningful and contradicts the plain statement of purpose in § 2(b). Id. at 42. Taamneh cites § 2(b), which states that the purpose of JASTA is to provide the broadest possible basis to seek relief against entities that provide material support to terrorist organizations. Id.

Additionally, Taamneh asserts that that the couplet verbs “aid and abet” can refer to assisting people, rather than only specific acts or events, as Twitter contends. Id. at 38. Taamneh posits that for hundreds of years, United States courts have used the couplet to refer to people perpetrating a crime. Id. at 39. Taamneh argues that acts of terrorism are, by nature, not events that occur without any human involvement. Id. Therefore, Taamneh concludes, the only sensical interpretation of the statute is that a defendant is secondarily liable through aiding and abetting the humans involved, members of a terrorist organization, regardless of any specific act they may commit. Id.


Twitter urges the Supreme Court to adopt new common law rules regarding the secondary liability of aiding-and-abetting cases. Brief for Petitioner at 27. Twitter argues that the Court ought to require a showing that a defendant’s assistance was a significant factor in causing the specific act. Id. Specifically, Twitter claims that the knowledge element has been critical in common law aiding-and-abetting cases such as Halberstam, especially when a defendant has merely failed to prevent a misuse of its widely available online service. Id. at 36. Twitter contends that Halberstam’s rule that a secondary actor who knowingly assists may be liable for a foreseeable consequence of that assistance defines the extent of liability, not the term “principle violation.” Id. at 34. In other words, Twitter concludes, Halberstam does support the conclusion that a defendant who unknowingly assisted a general terrorist organization campaign is secondarily liable for a specific attack. Id.

Twitter argues that, to be held liable, it should have at least been aware that Masharipov or ISIS directors created Twitter accounts to commit the Reina attack and subsequently failed to delete those accounts. Id. at 36. Furthermore, Twitter argues that the second part of the knowledge element requires that Twitter knew that failing to delete such accounts would substantially assist the perpetrator. Id. at 37. Twitter concludes that since Twitter did not meet the first part of the knowledge element, it is not secondarily liable under JASTA. Id.

On the other hand, Taamneh counters that the Court must not adopt new rules that restrict the scope and extent to which plaintiffs may recover under the ATA. Brief for Respondent at 62. Taamneh argues that the Court must hold a defendant secondarily liable for aiding and abetting even if the defendant did not have explicit knowledge or if they failed to take more active actions to prevent the general terrorist campaign. Id. at 69-70. Taamneh contends that Twitter disregards the D.C. Circuit’s distinction in Halberstam between the knowledge of assistance of wrongful conduct and the general awareness of a defendant’s assisting role in that conduct. Id. at 63. Taamneh concedes that a defendant who has no knowledge of any assistance it offers to a terrorist organization’s campaign is not liable under the knowledge requirement. Id. at 64. However, Taamneh contrasts such a case with the case at bar since Twitter had the general knowledge of its role in spreading ISIS’s propaganda globally on its platform, per Halberstam’s requirement. Id. at 64.

Taamneh further alleges that ISIS members use Twitter to recruit, issue threats, and grow into one of the most recognizable terrorist organizations in the world. Id. at 54. Furthermore, Taamneh maintains that Twitter’s algorithms allow users to locate ISIS-related content more easily. Id. at 75. Taamneh claims limiting the aiding-and-abetting principle to quintessential forms of assistance to terrorism, such as providing weapons used in the attack, is impractical because ISIS receives substantial help from its sponsors in forms of cash and the ability to recruit. Id. at 54. Thus, Taamneh concludes that Twitter is secondarily liable for knowingly assisting ISIS’s general campaign in substantial ways by failing to monitor its social media platform and preventing ISIS members from utilizing Twitter to grow into the global threat that it is. Id.



The Center for Democracy & Technology and related organizations (“The Center”), in support of Twitter, contend that given the size and reach of the internet, there is a high likelihood that website content may be associated with terrorists and therefore virtually all online intermediaries could be accused of having generalized knowledge of such content. Brief of Amici Curiae The Center for Democracy & Technology, et al., in support of Petitioner at 18. The Center argues that, because of this reality, online intermediaries will be forced to conduct overly aggressive moderation so as to avoid the accusation that they aid terrorism, resulting in suppression of constitutionally protected speech. Id. at 19. The Computer & Communications Industry Association, other trade associations, and non-profits, in support of Twitter, posit that online intermediaries should be given deference because as the internet has grown, content moderation has become increasingly costly and difficult. Brief of Amici Curiae Computer & Communications Industry Association, et al., in support of Petitioner at 19.

Senator Charles E. Grassley, in support of Taamneh, counters that the Supreme Court already considered First Amendment concerns with a similar anti-terrorism statute, the Anti-Terrorism and Effective Death Penalty Act, in Holder v. Humanitarian Law Project, and held that First Amendment concerns could not prevail. Brief for Amicus Curiae Senator Charles E. Grassley, in support of Respondents at 20. 470 Victims of terrorist attacks, in support of Taamneh, also contend that concerns regarding overbreadth are misplaced because the purpose of JASTA is to provide the broadest possible basis for plaintiffs to claim relief. Brief for Amici Curiae 470 Victims of Terrorist Attacks, in support of Respondents at 23. Concerned Women for America, in support of Taamneh, further argue that Twitter could have done more to limit terrorist use of its platform, but it chose not to, and in fact, ignored requests from the U.S. government to do so. Brief for Amicus Curiae Concerned Women for America, in support of Respondents at 8.


The Chamber of Commerce of the United States of America and several business associations (“the Chamber”), in support of Twitter, argue that if Congress wanted to cast a broad net of liability under JASTA, then it would have used language broader than “substantial assistance.” Brief of Amici Curiae the Chamber of Commerce of the United States of America, et al., in support of Petitioner at 27. The Chamber contends that a narrow view of liability under JASTA is also consistent with popular court of appeals precedent set in Halberstam v. Welch. Id. at 28. The Pharmaceutical Research and Manufacturers of America (“PhRMA”), in support of Twitter, also posit that if the Court affirms the Ninth Circuit’s scope of liability under JASTA, then pharmaceutical companies’ ability to provide medical care to conflict-ridden regions will be crippled due to fear of accusations of aiding terrorism. Brief of Amicus Curiae the Pharmaceutical Research and Manufacturers of America, in support of Petitioner, at 6-7. The Institute of International Bankers, in support of Twitter, asserts that a broad scope of liability under JASTA would critically hamper banks from being able to conduct international business out of fears similar to those PhRMA raises. Brief of Amicus Curiae Institute of International Bankers, et al., at 7-8.

The Anti-Defamation League, in support of Taamneh, counters that the narrow scope of liability Twitter proposes would effectively render JASTA a “dead letter” because of the difficulty of tracing specific goods and services to specific terrorist acts. Brief of Amicus Curiae Anti-Defamation League, in support of Respondents at 25. Former National Security Officials (“the Officials”), in support of Taamneh, further argue that Congress explicitly instructed that JASTA is to be read as broadly as possible so that it may reach those who aid in terrorism either directly or indirectly. Brief of Amici Curiae Former National Security Officials, in support of Respondents at 23. The Officials also posit that it is because of the difficulty in tracing specific aid given to terrorists that JASTA serves to punish those who offer “generalized aid” to terrorists or those associated with terrorists. Id. at 29. Further, Anti-Terrorism Act Scholars, in support of Taamneh, argue that a narrower scope of liability under JASTA would be in conflict with both congressional purpose behind JASTA, and the D.C. Circuit’s reasoning in Halberstam. Brief of Amici Curiae Anti-Terrorism Act Scholars, in support of Respondents at 13.


Written by:

Hailie Yoo

Gigi Scerbo

Edited by:

Tori Staley


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