2 TWITTER, INC. v. TAAMNEH Syllabus for failure to state a claim, but the Ninth Circuit reversed. Held: Plaintiffs’ allegations that these social-media companies aided and abetted ISIS in its terrorist attack on the Reina nightclub fail to state a claim under 18 U. S. C. §2333(d)(2). Pp. 6–31. (a) In 2016, Congress enacted the Justice Against Sponsors of Terrorism Act (JASTA) to impose secondary civil liability on anyone “who aids and abets, by knowingly providing substantial assistance, or who conspires with the person who committed such an act of international terrorism.” §2333(d)(2). The question here is whether the conduct of the social-media company defendants gives rise to aiding-and-abetting liability for the Reina nightclub attack. Pp. 6–8. (b) The text of JASTA begs two questions: What does it mean to “aid and abet”? And, what precisely must the defendant have “aided and abetted”? Pp. 8–21. (1) Nothing in the statute defines any of the critical terms in the phrase “aids and abets, by knowingly providing substantial assistance.” The term “aids and abets,” however, is a familiar common-law term and thus presumably “brings the old soil” with it. Sekhar v. United States, 570 U. S. 729, 733. Congress also provided additional context in JASTA by pointing to Halberstam v. Welch, 705 F. 2d 472, as “provid[ing] the proper legal framework” for “civil aiding and abetting and conspiracy liability.” 130 Stat. 852. Halberstam’s legal framework, viewed in context of the common-law tradition from which it arose, confirms that “aids and abets” in §2333(d)(2) refers to a conscious, voluntary, and culpable participation in another’s wrongdoing. Pp. 9–17. (i) In Halberstam, the D. C. Circuit undertook an extensive survey of the common law with respect to aiding and abetting and synthesized the surveyed cases as resting on three main elements: (1) there must be a wrongful act causing an injury performed by the person whom the defendant aided; (2) at the time assistance was provided, the defendant must have been “generally aware of his role as part of an overall illegal or tortious activity;” and (3) the defendant must have “knowingly and substantially assist[ed] the principal violation.” 705 F. 2d, at 477. The court then articulated six factors to help determine whether a defendant’s assistance was “substantial.” They are (1) “the nature of the act assisted,” (2) the “amount of assistance” provided, (3) whether the defendant was “present at the time” of the principal tort, (4) the defendant’s “relation to the tortious actor,” (5) the “defendant’s state of mind,” and (6) the “duration of the assistance” given. Id., at 488 (emphasis deleted). Halberstam also clarified that those who aid and abet “a tortious act may be liable” not only for the act itself but also “for other reasonably foreseeable acts done in connection with it.” Id., at 484. Finally, the court warned that its formulations should “not