International criminal law — Command responsibility — Whether concept of command responsibility applicable to non-international armed conflict — Command responsibility as a method of enforcing responsible command — Whether a superior responsible for failure to punish acts committed prior to that person assuming command — Customary international law — Existence of criminal responsibility — Principle of legality

Sources of international law — Customary international law — State practice — Opinio juris — Application of a principle of customary international law — Interpretation of customary international law — Relationship of criminal liability to customary international law — Principle of legality

International tribunals — International Criminal Tribunal for the Former Yugoslavia — Power of the Tribunal to apply and interpret customary international law