Page:Twitter v. Taamneh.pdf/14

8 §2333(d)(2). The central question is thus whether defendants’ conduct constitutes “aid[ing] and abett[ing], by knowingly providing substantial assistance,” such that they can be held liable for the Reina nightclub attack. Ibid.

As always, we start with the text of §2333. See Bartenwerfer v. Buckley, 598 U. S. 69, 74 (2023). Here, that text immediately begs two questions: First, what exactly does it mean to “aid and abet”? Second, what precisely must the defendant have “aided and abetted”?

We turn first to the meaning of the phrase “aids and abets, by knowingly providing substantial assistance.” Nothing in the statute defines any of those critical terms. Yet terms like “aids and abets” are familiar to the common law, which has long held aiders-and-abettors secondarily liable for the wrongful acts of others. See Central Bank of Denver, N. A. v. First Interstate Bank of Denver, N. A., 511 U. S. 164, 181 (1994). We generally presume that such common-law terms “brin[g] the old soil” with them. Sekhar v. United States, 570 U. S. 729, 733 (2013) (internal quotation marks omitted). In enacting JASTA, Congress provided additional context by pointing to Halberstam v. Welch, 705 F. 2d 472 (CADC 1983), as “provid[ing] the proper legal framework” for “civil aiding and abetting and conspiracy liability.” §2(a)(5), 130 Stat. 852. We thus begin with Halberstam’s “legal framework,” viewed in context of the common-law tradition from which it arose.