Normative Dimensions of Sovereignty Under Public International Law
Under present-day public international law, sovereignty is not what it used to be1: during the “classical” period of international law, sovereignty meant the exclusive legal power of a state to regulate matters within its own territory according to its own will (Lauterpacht 1997, 140). Since the end of the First World War and with an ever increasing speed and substantive scope, states have concluded international treaties by which they limit their freedom of action, both within and outside their own territories. While some conclude, therefore, that “sovereignty on the international plane . . . must be seen largely as a myth” (Lauterpacht 1997, 149), others rightly propose that the meaning of sovereignty has not changed (Schrijver 1999, 98). Sovereignty today still means what it meant since the beginning of the Westphalian sys?tem: the legal—not factual-equality of states. Because of this “sovereign equality of states” (article 2.1, U.N. Charter), a state cannot be bound under international law by a treaty concluded between other states against its will (article 34, Vienna Convention on the Law of Treaties), even if these states are more powerful than itself.
Although sovereignty has not changed conceptually, its appearance differs from earlier times. Most relevant for present purposes is the extent to which states have limited themselves through international law. In particular the states’ reserved domain was reduced considerably through rules that regulate the internal actions of states. As a consequence, the scope of application of the prohibition of (nonmilitary) intervention shrank enormously: other states and international organizations are allowed to take an interest in state actions in areas hitherto within the reserved domain of states. With these subject-matters turning into objects of international concern, the absolute protection of states through the prohibition of the use of force became increasingly problematic. This development is reflected in the debate on “humanitarian intervention,” whether unilateral or based on a decision of the U.N. Security Council under chapter 7 of the charter.
A second important change of sovereignty occurred through the acceptance of states that certain rules of public international law are peremptory norms (ius cogens) and hence cannot be changed by agreements between individual states (article 53, Vienna Convention on the Law of Treaties). These rules of ius cogens embody the fundamental values of the international legal order. Consequently, any exercise of state power in contravention of these norms constitutes a grave assault on the international legal order. Moreover, and even more important in the present context, the existence of ius cogens proves that sovereignty is not absolute, but that, on the contrary, there are some absolute limits to sovereignty.