All States, large or small, rich or poor, are equal in the eyes of international law. Each State is sovereign and independent. Statehood is vested with the type of sovereignty and independence that is recognized as exclusive and absolute within its territory. It is by reason of this absolute and exclusive sovereignty and this equality of States and their mutual independence, that in certain circumstances, a State is presumed to have consented to waive the exercise of its jurisdiction which is exclusive within its territory in a proceeding in which another State is being proceeded against without its consent. In other words, the territorial State is presumed to have consented to refrain from exercising its jurisdiction. This abstention or non-exercise of jurisdiction by the territorial State is in recognition of its international obligation of a principle of international law as expressed in the general notion of jurisdictional immunities of States.
Sucharitkul, Sompong, "Immunities from Jurisdiction in Contemporary International Law" (2002). Publications. 548.