Modern International Law

Modern International Law
a). In the 17th and 18th centuries
The law of nations has a new name as international law. [7] This new understanding affects the content of international law itself, namely the separation of domestic and international issues. This distinction is due to the emergence of the concept of sovereignty of the Peace of Westphalia agreement aimed at ending the war between religious groups which lasted more than 30 years in Europe. [8]
There is a tendency from legal experts to put forward the rules of international law, especially in the form of treaties and customs and reduce the natural law as little as possible as a source of these principles. [9] Notable writers in the 17th and 18th centuries included: Cornelis Van Bynkershoek (1673-1743), who put forward the importance of the actual practice of states rather than natural law.
Another thought contribution theory about the rights and obligations of a neutral state. Christian Wolf (1632-1694), put forward a theory about the Civitas Maxima which as a world country includes the countries of the world. Von Martens (1714-1767), in Receuil des Traites is a collection of agreements that is still a valuable collection until now. Emmerich De Vattel (1714-1767) introduced the principle of equality between countries.

b). In the 19th century
International law develops even further. Some factors that influence this development are the rise of new countries, both inside and outside the European continent, the modernization of world transportation facilities, new discoveries, especially in the field of military weaponry for war. All of this raises the need for a strict international legal system to regulate international relations.
This century also experienced the development of the rules of war and neutrality, as well as an increase in the settlement of international cases through international arbitration institutions. The practice of countries is also getting used to making treaties to regulate relations between countries. The work of legal experts, more attention on current practices and set aside the concept of natural law, although it does not leave reason and justice, especially if something is not regulated by treaties or customs. [10]

c). 20th Century and Today
International law experienced significant developments. In this century the Permanent Court of Arbitration was established at the Hague Conference of 1899 and 1907. The establishment of the Permanent Court of International Justice as an international judicial court in 1921, this court was replaced by the International Court of Justice in 1948 until now. .
Also formed an international organization whose function resembles that of world government for the purpose of peace and welfare of mankind, such as the League of Nations, which was later replaced by the United Nations. The expansion of the scope of multiulateral treaties not only in the socio-economic field but also includes the protection of fundamental rights and freedoms of individuals. International law experts focus more on practices and court decisions. [11]

Sources of International Law
International legal sources are formal and material legal sources. Formal legal sources determine what constitutes law while material sources only indicate where the law can be found. [1]

International Agreement
International treaties are one source of international law. International agreements play an important role in regulating international relations between subjects of international law in general. Compared with other sources of international law, international treaties provide more guarantees of legal certainty to the parties bound in them.
Because in its written form where the rights and obligations of the parties are clearly formulated, it will be easier to implement. [2] It can be said that in the body of international law there are international treaties. International treaties are agreements made between members of the peoples of nations and aim to have certain legal consequences. International Treaties Law held in Vienna in 1968 stated that this convention only regulates agreements between states.

It is not meant to say that only the country can participate in international agreements, but the Conference considers it necessary to regulate agreements entered into by international organizations or agencies separately. [3
In every agreement including international treaties there are principles which are used as a basis for implementation. The most fundamental principle is the principle of pacta sunt servanda, namely that the promise is binding as the law for those who make it. [4]