Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-1496_d18f.pdf
Page Number: 21

Cite as:  598 U. S. ____ (2023) 

15 

Opinion of the Court 

of some sort is necessary to justify punishment of a second-
ary actor,” lest mostly passive actors like banks become lia-
ble for all of their customers’ crimes by virtue of carrying 
out routine transactions.  Monsen v. Consolidated Dressed 
Beef Co., 579 F. 2d 793, 799 (CA3 1978).  And others have 
suggested that “inaction cannot create liability as an aider 
and abettor” absent a duty to act.  Zoelsch, 824 F. 2d, at 36; 
see also Woodward, 522 F. 2d, at 96. 

In articulating those limits, courts simultaneously began
to  crystalize  the  framework  for  aiding  and  abetting  that 
Halberstam identified and applied.  See, e.g., Monsen, 579 
F. 2d, at 799 (stating a similar three-part test).10  As in Hal-
berstam, that framework generally required what the text 
of  §2333(d)(2)  demands:  that  the  defendant  have  given
knowing and substantial assistance to the primary tortfea-
sor.  See, e.g., Monsen, 579 F. 2d, at 799; Landy, 486 F. 2d, 
at  162–163.  Notably,  courts  often  viewed  those  twin  re-
quirements as working in tandem, with a lesser showing of 
one demanding a greater showing of the other.  E.g., Wood-
ward,  522  F. 2d,  at  97;  Woods  v.  Barnette  Bank  of  Ft. 
Lauderdale,  765  F. 2d  1004,  1010  (CA11  1985).    In  other 
words,  less  substantial  assistance  required  more  scienter 
before a court could infer conscious and culpable assistance.
See Woodward, 522 F. 2d, at 97.  And, vice versa, if the as-
sistance were direct and extraordinary, then a court might 
more readily infer conscious participation in the underlying 
tort.  See ibid.  In moving back and forth between all these 
guideposts,  the  courts  thus  largely  tracked  the  same  dis-
tinctions  drawn  above  to  ensure  that  liability  fell  only  on 

—————— 

10 Others, however, have wondered whether any of these “elaborate dis-
cussions of the aiding and abetting standard . . . ‘have added anything 
except  unnecessary  detail’ ”  to  the  formulation  set  forth  by  Judge 
Learned Hand in United States v. Peoni, 100 F. 2d 401 (CA2 1938), and 
adopted by this Court in Nye & Nissen v. United States, 336 U. S. 613 
(1949).  SEC v. Apuzzo, 689 F. 3d 204, 212, n. 9 (CA2 2012) (quoting IIT, 
an Int’l Inv. Trust v. Cornfeld, 619 F. 2d 909, 922 (CA2 1980)).