Given that there are few states, diverse and atypical in character, inexplicable, without a centralized sovereign power and their agreements are insurgent and decentralized, and then, Wight says, “international society is not a society at all. The best way to describe the state of international relations is international anarchy; In 2016, when the Paris climate agreement came into force, the United States was one of the main drivers of the agreement and President Obama hailed it as “a tribute to American leaders.” As the presidential candidate at the time, Donald Trump criticized the deal as a bad deal for the American people and promised to withdraw the United States if elected. The Dutch jurist Hugo Grotius (1583-1645) is widely regarded as the most pioneering figure in international law and is one of the first scholars to articulate an international order consisting of a “society of states” governed not by violence or war, but by real laws, agreements and customs.  Grotius secularized international law and organized it into a global system; His work De Jure Belli ac Pacis (On the Law of War and Peace) of 1625 established a system of principles of natural law that bound all nations regardless of stakes or local laws. He also highlighted the freedom of the high seas, not only relevant to the growing number of European states exploring and colonizing the world, but which remains today a cornerstone of international law. Although the modern study of international law did not take place until the early 19th century The sixteenth-century scholars Gentili, Vitoria and Grotius laid the foundations and are widely regarded as the “fathers of international law”.  The origins of international law date back to antiquity. Early examples include the peace agreements between the Mesopotamian city-states of Lagash and Umma (about 2100 BC) and an agreement between the Egyptian pharaoh Ramses II and the Egyptian king Hattouilis III, concluded in 1258 BC. Intergovernmental pacts and agreements of various kinds have also been negotiated and concluded by communities around the world, from the Eastern Mediterranean to East Asia. One of the most important scholars of the League of Nations was Sir Alfred Zimmern. Like many other British fans of the league, such as Gilbert Murray and Florence Stawell — the so-called “Greece and Peace” set — he arrived studying the classics.
During the European Middle Ages, international law focused primarily on the purpose and legitimacy of war and sought to determine what constituted a “just war.” For example, the ceasefire theory asserted that the nation that provoked an unjustified war could not enjoy the right to receive or win legitimate trophies at that time.  The concept of Greco-Roman natural law was combined with religious principles by the Jewish philosopher Moses Maimonides (1135-1204) and the Christian theologian Thomas Aquinas (1225-1274) to create the new discipline of the “law of nations,” which, unlike his Roman predecessor of the same name, applied natural law to relations between states. A similar framework was developed in Islam, in which the law of nations was partially derived from the principles and rules established in treaties with non-Muslims.  `treaty` means an international agreement concluded in writing between states and subject to international law, whether enshrined in a single act or in two or more interconnected conventions, and regardless of its particular name” Nation-states respect the principle par in parem non habet imperium: “There is no sovereign power between equals”. . . .