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16 

TWITTER, INC. v. TAAMNEH 

Opinion of the Court 

those  who  had  abetted  the  underlying  tort  through  con-
scious, “culpable conduct.”  Camp, 948 F. 2d, at 460. 

3 
Halberstam’s  framework  reflected  and  distilled  those 
common-law principles.  Indeed, Halberstam started with a 
survey of many earlier common-law cases, including many
of the same cases cited above.  705 F. 2d, at 477, 483 (citing, 
e.g.,  Woodward, 522 F. 2d, at 94–95; Landy, 486 F. 2d, at 
162–163; Duke, 245 Md., at 457–458, 226 A. 2d, at 347).  As 
part of that survey, Halberstam explicitly distinguished dif-
ferent  types  of  aid  along  the  same  culpability  axis  that 
grounded the common law.  705 F. 2d, at 481–483.  For ex-
ample,  Halberstam  recognized  that  giving  verbal  encour-
agement (such as yelling “ ‘Kill him!’ ”) could be substantial 
assistance, id., at 481, but that passively watching an as-
sault after hearing an assailant threaten the victim likely
would not be, id., at 483.  Those same lines have long been
drawn for aiding-and-abetting liability under the common 
law.  See Rosemond, 572 U. S., at 70; see also, e.g., 2 LaFave 
§13.2(a), at 457–460; Restatement (Second) of Torts §876, 
Comment  d,  Illus.  9–10,  at  318;  Brown,  83  Mass.,  at  98. 
And  Halberstam’s  six  factors  for  “substantial  assistance” 
call for the same balancing that courts had undertaken pre-
viously between the nature and amount of assistance on the 
one  hand  and  the  defendant’s  scienter  on  the  other.    705 
F. 2d, at 484–485, 487–488. 

Despite  that  deep-rooted  common-law  basis,  the  Ninth
Circuit  appears  to  have  understood  JASTA’s  approval  of 
Halberstam’s  “legal  framework”  as  requiring  it  to  hew 
tightly  to  the  precise  formulations  that  Halberstam  used. 
The parties before us similarly make a conscious effort to
draw analogies to the facts of that case.  But any approach 
that  too  rigidly  focuses  on  Halberstam’s  facts  or  its  exact 
phraseology risks missing the mark.  Halberstam is by its
own  terms  a  common-law  case  and  provided  its  elements