Crosby v. Twitter, Inc., 921 F.3d 617 (6th Cir. 2019) was decided by the United States Court of Appeals for the Sixth Circuit on April 16, 2019 (No. No. 18-1426). The Sixth Circuit affirmed dismissal of the ATA claims. Crosby establishes in that circuit that generalized platform availability to a terrorist organization does not proximately cause an attack by an individual the platform never dealt with. It is a foundational proximate-cause decision in the line of social-media terrorism suits later reshaped by Twitter v. Taamneh.
The question before the court
Can victims of an attack by a self-radicalized domestic shooter recover under the Anti-Terrorism Act from social media companies whose platforms hosted the terrorist propaganda he consumed, where no defendant had any connection to the shooter himself?
The governing rule
18 U.S.C. Sec. 2333(a) permits recovery only for injuries sustained 'by reason of an act of international terrorism,' which imports a proximate-cause requirement; 18 U.S.C. Sec. 2333(d) supplies secondary liability for aiding and abetting the person who committed such an act. Direct liability was pressed under 18 U.S.C. Sec. 2339B(a)(1) (material support to a designated foreign terrorist organization) read together with the Sec. 2331(1) definition of international terrorism. The court applied Kemper v. Deutsche Bank AG, 911 F.3d 383 (7th Cir. 2018), and aligned with Owens v. BNP Paribas, S.A., 897 F.3d 266 (D.C. Cir. 2018), Fields v. Twitter, Inc., 881 F.3d 739 (9th Cir. 2018), and Rothstein v. UBS AG, 708 F.3d 82 (2d Cir. 2013).
How the court applied it
After Omar Mateen killed forty-nine people at the Pulse Night Club in Orlando in June 2016, victims and families sued Twitter, Facebook, and Google rather than Mateen or ISIS. The amended complaint alleged that ISIS used the defendants' platforms from 2010 onward to spread propaganda and virtually recruit, that the defendants knew of this and left accounts up under a renaming scheme the court likened to whack-a-mole, and that Mateen self-radicalized on that material. Writing for the panel, Judge Nalbandian treated the ATA as a tort statute in which causation must be proven before liability attaches. Because Sec. 2333(a) uses the phrase 'by reason of,' proximate cause is required, consistent with Holmes and Bridge and with three sister circuits. The court declined to resolve whether providing routine social media services could itself be an act of international terrorism, holding instead that even if it could, liability would not be unlimited. On the definition of proximate cause the court refused to choose between foreseeability and directness, adopting the view that the two are logically linked and that the Supreme Court favors a flexible catch-all approach. Applying that standard, the pleadings offered only tenuous links: the platforms existed, ISIS posted on them, and someone sympathetic might eventually see the material. The complaint alleged no direct connection between any defendant and Mateen, and no material support furnished to Mateen. The aiding-and-abetting claim failed for the same want of connection.
What the court concluded
The Sixth Circuit affirmed dismissal of the ATA claims. Crosby establishes in that circuit that generalized platform availability to a terrorist organization does not proximately cause an attack by an individual the platform never dealt with. It is a foundational proximate-cause decision in the line of social-media terrorism suits later reshaped by Twitter v. Taamneh.
From the opinion
- “"Plaintiffs' complaint includes no allegations that Twitter, Facebook, or Google had any direct connection to Mateen or his heinous act."”
- “"the ATA ultimately is a tort statute"”
- “"a butterfly in China is not the proximate cause of New York storms"”
Why it matters for cyber conflict
Crosby sets the causation ceiling for claims that online infrastructure enabled a violent act, a limit that constrains any theory holding network operators liable for hostile influence operations conducted over their services.
Editorial note: this case note was drafted with AI assistance by the JLCW Research Desk, checked against the text of the opinion, and reviewed by a human editor before publication. Every quotation above is carried through from the opinion itself. See our editing policy.
Read the opinion: Crosby v. Twitter, Inc. on CourtListener. This note is a summary prepared by the Journal, not legal advice, and not a substitute for the opinion itself.
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