The expansion and development of international law can be divided into four main stages:
The first phase
The first and perhaps most important phase in the development and expansion of international law began with Westfale's peace, which was a peace treaty signed to end the thirty-year war struck in Europe from 1618-1648. The most important participants in the treaties were France and Sweden on one side with their opponents Spain and the Holy Roman Empire on the other side. Under the terms of the treaty, each state would be recognized as sovereign and independent of the Holy Roman Empire, making the Holy Roman emperor virtually powerless, which then led to the collapse of the Roman Empire.
Eventually, the peace treaty hat was not able to maintain the eternal peace in Europe as expected and as such between 1914 and 1918 there was the First World War. In 1919, the Versailles Treaty was reached between Germany and its allies on one side and Britain and its allies on the other side to end World War II. The Versailles treaty made a proposal to create an independent organization to ensure that the treaties entered into in the treaty are held high by all members, and this led later to the creation of the UN Covenant 1920. An important note here is that with the creation of United Nations relations adopted international laws and norms of member states on how the people's congress would act as a shift from international law governing relations between states alone as seen in the traditional concept of controlling the function and relationship between an international organization which in this case is the Nation's covenant.
With the union's failure to maintain world peace and later lead to World War II, which was partly due to the fact that Germany was not satisfied with most of the provisions of the Versailles Treaty because Germany considered that the treaty was not fair for them and that all efforts were deliberately made by the Treaty of to make Germany powerless and weak (Boemeke, & Feldman, 1998). The Paris Peace Agreement was signed on October 10, 1949, to end the Second World War, which has led to the destruction of thousands of lives, property and materials around the world. The United Nations was then created as an international government organization to maintain world peace and ensure peaceful coexistence between member states.
The fourth phase
The final stage of development is the period after World War II until today. After World War II, the world experienced a drastic increase in the number of NGOs that grow up daily both locally and internationally. The activities and activities of these NGOs, especially international, are also largely governed by international law. These NGOs work within the international framework and ensure that their activities do not violate any international law for that matter. NGOs have legal status and as such have the right to sue and sue in an international court, which means that if their activities are in any way contrary to international law, they are responsible for their offenses and will be held responsible in this respect.
In addition, after World War II, the world's business occurred not only between states but also between individuals in different nations, and thus it was also necessary to come up with international laws governing such relationships between people as well. It is in this regard that an international branch called private international law came to. The need to have standard rules and rules for regulating relations between individuals from different countries when they trade between themselves led to the emergence and development of private international law. Different states have their own laws governing trade and business in the domestic market and this can lead to misunderstandings between business partners about which state laws are applicable in disputes and hence the essence of private international law.
The point to note here is that the scope and function of international law in the fourth stage referring to the aftermath of the Second World War to the present day has increased. International law governs not only the behavior, relationships and affairs of sovereign states, IGO, NGOs, but also governs relationships between individuals. Day in and day out there is always an improvement in both private and public international law in order to help maintain relations with all subjects in international law in a peaceful and cordial way.