It is, in certain cases, impossible for persons to tell in advance which states will have effective legislative jurisdiction over their acts. In these cases, it is impossible to tell in advance whose law the person must obey. This quandry arises where some national law purports to regulate outsiders and their acts in a manner arguably inconsistent with the international law of legislative jurisdiction. If the regulating state's courts do not allow challenges to jurisdiction based on international law, and the state of the outsider's nationality fails to protect her diplomatically, the outsider has no protection against excessive claims of jurisdiction.
Some common law states, like the United States, have no thorough jurisdictional provisions in their criminal codes. In the United States, the presumption against extraterritorial effect, revitalized in the non-criminal case of Morrison v. Australia National Bank (U.S.S.Ct. 2010), can assist in minimizing the problem of "surprise" jurisdiction over persons who had no reason to know that they would be subject to United States criminal laws which do not specify the territory, persons, and situations outside the U.S. to which they apply.
The presumption against extraterritorial effect might sensibly be given an "elemental" reading. The presumption against extraterritoriality would be triggered if neither subjective territoriality (an act committed in the U.S. constitutes an element of an offense) or objective territoriality (a result which is an element of the crime occurs on U.S. territory) is present. It is hard to believe that any state would give up the general right to control either wrongful acts or illegal effects on its own territory, despite statements made by certain countries in the Morrison litigation and its aftermath.
In developing this argument, this paper suggests that, on average, in recent decades, Congress has been more attuned to the obligations of the United States as an entity under the international law of jurisdiction than have been the Courts.
Kenneth S. Gallant, The Indeterminate International Law of Jurisdiction, the Presumption Against Extraterritorial Effect of Statutes, and Certainty in U.S. Criminal Law, 27 Pac. McGeorge Global Bus. & Dev. L.J. 219 (2014).