One only has to look into the history of international relations to realize that the use of force has been intrinsically related to the ius gentium. For example, it is quite revealing that international law, as a scientific discipline, emerged from this relation. There are also many publications from the founding fathers that are related to this branch of law and which tittles specifically mentioned the law in war. To this end, one can relate to the works of De Vitoria, Suarez, Molina, Grotius, etc. Thus, it would not be too bold to claim that the modern international order was born from the regulation of the use of force and so, since the Renaissance. The banishment of the use of force in international relations surely is the cornerstone of the UNC, this new social contract that would now exist between the nations that had defeated the Nazi-fascist barbarism and the Japanese imperialism. Yet, this rule, true and veritable idea that it was, did not emerge overnight but was the fruit of a long and laborious process from different stages of which will be presented in the following pages. It is fair to wonder how did we get to the current framework of the use of force and more specifically how States, those who are the very legislators of international law, have supplanted the law regulating the use of force; ius ad bellum, by the law on the prevention of war; ius contra bellum. Was it not Clausewitz who once claimed that war was nothing else but the extension of politics by other means, therefore being considered like any other (lawful) means and moreover, a sovereign right of States? UNC Article 2 (4) ([1]) enshrines this epochal revolution, yet this was the end point of a lengthy if not laborious historical and legal process. It is then of paramount relevancy to pinpoint the various steps of its development.

([1]) United Nations, Charter of the United Nations, October 24, 1945, 1 UNTS, article 2§4: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations”.