A Question About Kiobel
It’s always dangerous to opine on a judgment you have only skimmed, so I’ll phrase my thought as a question instead. Here is what the ATS Statute says:
The district courts shall have original jurisdiction of any civil action by an alien for a tort only, committed in violation of the law of nations or a treaty of the United States.
The key expression is “committed in violation of the law of nations.” Whether an act violates the law of nations is determined by the substantive rules of international law: the definitions of international crimes, the modes of participation available for those international crimes, and the possible defenses to those international crimes. Jurisdictional rules are completely separate from those substantive rules; jurisdictional rules determine who can be prosecuted for a violation of the law of nations, not whether substantive rules have been violated.
Consider, for example, a 12-year-old child soldier who aids-and-abets a war crime during a non-international armed conflict and has no defense for his actions. International law would not permit an international tribunal to prosecute that child soldier, nor is there a general principle of criminal law that permits prosecuting child soldiers that young. But we would not say that the child soldier has not committed a “violation of the law of nations.” He has — he simply cannot be prosecuted for that violation. So how is the situation in Kiobel any different?