On May 18, 2023, the Supreme Court issued a decision in Twitter, Inc. v. Taamneh, et al.,[1] unanimously rejecting claims against Twitter, Facebook and Google (as the owner of YouTube) for allegedly aiding and abetting ISIS in its commission of terrorist attacks. Plaintiffs, who were injured in an ISIS-sponsored terrorist attack on the Reina nightclub in Istanbul in 2017, alleged that Twitter, Facebook and Google were liable under the Anti-Terrorism Act (“ATA”), 18 U.S.C. § 2333(a), as amended by the Justice Against Sponsors of Terrorism Act (“JASTA”), 18 U.S.C. § 2333(d)(2), because they allegedly knowingly allowed ISIS to use their social media platforms and “recommendation” algorithm tools, profited from advertising revenue on ISIS content, and failed to take sufficient steps to remove ISIS-affiliated accounts. The Supreme Court held that these allegations were insufficient to establish aiding and abetting liability under JASTA, in a decision that substantially clarifies the circumstances under which companies in the U.S. who offer widely-available and generalized services may be liable for complicity in terrorist attacks.