Held. (Per curiam) No. A rule of international law, which prohibits a state from exercising criminal jurisdiction over a foreign national who commits acts outside of the state’s national jurisdiction, does not exist. Failing the existence of a permissive rule to the contrary is the first and foremost restriction imposed by international law on a state and it may not exercise its power in any form in the territory of another state.
This does not imply that international law prohibits a state from exercising jurisdiction in its own territory, in respect of any case that relates to acts that have taken place abroad which it cannot rely on some permissive rule of international law. In this situation, it is impossible to hold that there is a rule of international law that prohibits Turkey (D) from prosecuting Demons because he was aboard a French ship. This stems from the fact that the effects of the alleged offense occurred on a Turkish vessel.
Hence, both states here may exercise concurrent jurisdiction over this matter because there is no rule of international law in regards to collision cases to the effect that criminal proceedings are exclusively within the jurisdiction of the state whose flag is flown.