Document ID: ./input/supremecourt_opinions/opinions/22pdf/21-1450_5468.pdf
Page Number: 25.0

6 

TURKIYE HALK BANKASI A. S. v. UNITED STATES 

GORSUCH, J., concurring in part and dissenting in part
Opinion of GORSUCH, J. 

“common law” path and the Court fails to supply guidance 
on how to resolve any of them.

Right out of the gate, lower courts will have to decide be-
tween two very different approaches.  One option is to defer 
to the Executive Branch’s judgment on whether to grant im-
munity to a foreign sovereign—an approach sometimes em-
ployed by federal courts in the years immediately preceding 
the FSIA’s adoption.  The other option is for a court to make 
the immunity decision looking to customary international
law and other sources.  Compare Brief for United States 21–
26 with Brief for Professor Ingrid (Wuerth) Brunk et al. as 
Amici Curiae 6–25. 

Whichever path a court chooses, more questions will fol-
low.    The  first  option—deferring  to  the  Executive—would 
seem to sound in separation-of-powers concerns.  But does 
this mean that courts should not be involved in making im-
munity determinations at all?  And what about the fact that 
the strong deference cases didn’t appear until the 20th cen-
tury; were courts acting unconstitutionally before then?  If 
not,  should  we  be  concerned  that  deference  to  the  Execu-
tive’s immunity decisions risks relegating courts to the sta-
tus  of  potted  plants,  inconsistent  with  their  duty  to  say 
what the law is in the cases that come before them?  See, 
e.g.,  Brief  for  Professor  Ingrid  (Wuerth)  Brunk  et al.  as 
Amici Curiae 17–21. 

The  second  option—applying  customary  international
law—comes with its own puzzles.  If the briefing before us
proves anything, it is that customary international law sup-
plies no easy answer to the question whether a foreign sov-
ereign  enjoys  immunity  from  criminal  prosecution.    Com-
pare  Brief  for  Professor  Roger  O’Keefe  as  Amicus  Curiae 
11–16 with Brief for Mark B. Feldman et al. as Amici Cu-
riae 12–13.  Nor is it even altogether clear on what author-
ity federal courts might develop and apply customary inter-
national  law.  Article  VI  of  the  Constitution  does  not  list