Final answer:
The application of U.S. law over acts committed outside its territory is based on international principles of state sovereignty and is reinforced by treaties and the supremacy clause of the U.S. Constitution. Jurisdiction in such cases is legitimized through treaties states entered into and accepted as binding laws.
Step-by-step explanation:
The question pertains to the principle of international law that is applied by U.S. courts to assert jurisdiction over acts committed outside the territorial limits of the country. The principle that allows for application of U.S. law in such instances is based on state sovereignty and the recognition that sovereign states can enter into treaties which bound them to certain obligations and legal standards. International law establishes that each state is bound by the treaties it signs, leading to a system of laws that sovereign states agree to follow, thus allowing for the exercise of jurisdiction when necessary.
Jurisdiction is a core concept in international law, signifying the territory within which authority can be legally exercised by a state. The supremacy clause of the U.S. Constitution reinforces this by establishing that federal laws and treaties are the supreme law of the land. This forms the basis on which U.S. courts extend their jurisdiction, ensuring that even when disputes involve parties or actions outside the U.S., the laws remain applicable as long as the treaties and principles agreed upon in international law are adhered to.