125 Another important duty of sovereignty is the obligation to respect international law and to cooperate with other subjects of international law in the implementation of international law (Article 2(2) of the Charter of the United Nations). Of course, this also includes legal obligations, but also moral obligations to support a just international system and the international rule of law. The moral duties to obey international law by law are more complex and have been dealt with in the previous section. It is important to note that these direct obligations to respect international law, as well as the legality of sovereign acts, concern only States. However, states are no longer the only subjects of international law, and other subjects, such as IOs and individuals, are increasingly endowed with direct obligations under international law, duties that cannot be explained through the prism of state sovereignty, but by the modern conception of popular sovereignty. Hobbes` theories decisively shape the concept of sovereignty through theories of the social contract. Jean-Jacques Rousseau`s (1712-1778) definition of popular sovereignty (with the first precursors of Francisco Suárez`s theory of the origin of power) provides that the people are the legitimate sovereign. Rousseau regarded sovereignty as inalienable; He condemned the distinction between origin and the exercise of sovereignty, a distinction on which constitutional monarchy or representative democracy is based. John Locke and Montesquieu are also key figures in the development of the concept of sovereignty; their views differ from those of Rousseau and Hobbes on this question of alienation. According to a standard division of your time, with the Peace of Westphalia of 1648, there was the final conclusion of a process that had begun four centuries earlier, to name only the smallest amount.
In other words, the State as a territorial entity appears to be the definite and primary subject of the current international order. This horizontal character of the new international order presupposes the centrality of the territory and thus the effective use of sovereign powers over it. The concept of territorial integrity is of fundamental importance to the Westphalian system of States and underpins contemporary rules of international law on the use of force, as enshrined in the Charter of the United Nations and customary international law. Many are now questioning this worldview. The growing importance of international human rights law, including the right to self-determination, has often been suggested to go beyond this view. However, these views are essentially political in nature and, from a legal point of view, it is difficult to see a weakening of the principle of territorial integrity. For example, it was concerns about territorial integrity and border stability that led the Organization of African Unity (now the African Union) to insist on maintaining colonial borders as it did with independence. Indeed, international law still places territorial integrity at the centre of the context of self-determination. Some would even go so far as to claim that the principle of territorial integrity in the era of globalization no longer has the meaning it once had. This is a point of view defended mainly by experts in international relations.
Few international lawyers would agree; The International Court of Justice recently affirmed that this principle is "an important part of the international legal order".  Article 2.4 of the Charter of the United Nations states: "All Members shall refrain, in their international relations, from threatening or using force against the territorial integrity or political independence of a State or in any other manner inconsistent with the purposes of the United Nations. The principle set out in Article 2.4, and thus the concept of territorial integrity, is taken up and elaborated on in important declarations of the United Nations General Assembly, including the 1970 Declaration on Friendly Relations and the 1974 Definition of Aggression. The words "against the territorial integrity and political independence of a State" were inserted into Article 2.4 of the Charter at the San Francisco Conference in 1945 to emphasize the importance of not violating territorial integrity and political independence; and they cannot (as is sometimes suggested) be interpreted as restricting the principle of non-use of force enshrined in the Charter. It is important to note that the notion of prohibition of the use of force, which reflects the principle of territorial integrity, protects the territory that is under the effective control and possession of a state, not just what it is entitled to de jure. .