## Facts

- On January 1, 2017, an ISIS-affiliated attacker carried out a mass shooting at the Reina nightclub in Istanbul, killing 39 people, including Nawras Alassaf.
- Alassaf’s relatives sued Twitter (and, in related proceedings, other platforms), alleging civil aiding-and-abetting liability under the Antiterrorism Act as amended by JASTA.
- Plaintiffs alleged ISIS used social-media platforms to recruit, raise funds, and spread propaganda, and that platform algorithms recommended ISIS content to interested users.
- Plaintiffs alleged the platforms knowingly allowed ISIS supporters to use their services and derived revenue connected to ISIS content.
- Plaintiffs did not allege the platforms were used to plan, coordinate, or carry out the Reina attack, or that defendants provided direct support to the attacker or the specific operation.
- The district court dismissed the complaint for failure to state a claim; the Ninth Circuit reversed as to aiding-and-abetting liability; the Supreme Court granted review.

## Issues

1. Whether plaintiffs plausibly alleged aiding-and-abetting liability under 18 U.S.C. § 2333(d)(2) based on defendants’ provision of generally available social-media services that ISIS allegedly used.
2. Whether generalized knowledge that ISIS used the platforms and alleged failure to remove ISIS content sufficiently showed “knowing” and “substantial assistance” to the Reina attack.

## Decision

- The Supreme Court unanimously reversed the Ninth Circuit and held the complaint failed to state a claim under § 2333(d)(2).
- Providing widely available, content-neutral platform services to the public at large, even if used by ISIS, did not plausibly constitute knowing and substantial assistance to the Reina attack.
- General awareness of ISIS presence on a platform, without allegations tying defendants’ conduct to the specific terrorist act that injured plaintiffs, was insufficient.
- The Court resolved the case on JASTA’s statutory requirements and did not reach any immunity questions.

## Legal Principles

- JASTA aiding-and-abetting liability requires: (1) a principal wrongful act causing injury; (2) the defendant’s general awareness of a role in the tortious or illegal activity when providing assistance; and (3) knowing and substantial assistance to the principal violation.
- The statute targets assistance to “the act of international terrorism” that injured the plaintiff, not generalized support to a terrorist organization’s overall operations.
- Routine, widely available services provided to many users, and alleged omissions or inadequate policing of misuse, ordinarily do not amount to “substantial assistance” absent a concrete nexus to the specific attack.
- Aiding-and-abetting under § 2333(d)(2) does not impose liability based on mere association with wrongdoers or broad theories that would treat failure to stop misuse as assistance to every downstream terrorist act.

## Conclusion

The Court held that JASTA does not plausibly impose civil aiding-and-abetting liability on social-media platforms where plaintiffs allege only that ISIS used routine platform features and defendants generally knew of that misuse, without well-pleaded facts showing knowing, substantial assistance to the particular terrorist attack that caused the injury.


Twitter, Inc. v. Taamneh, 143 S. Ct. 1206 (2023)