Modern legal positivists view international law as a unified system of rules based on the will of states. International law, as it stands, is an «objective» reality that must be distinguished from the law «as it should be». Classical positivism requires strict tests of legal validity and considers that all extra-legal arguments are irrelevant.  Since most international law derives from treaties that bind only those Parties ratifying or acceding to it, although European democracies tend to support broad and universalist interpretations of international law, many other democracies have different views on international law. Several democracies, including India, Israel and the United States, take a flexible and eclectic approach by recognizing aspects of international law such as territorial rights as universal, considering aspects other than those resulting from treaties or customs, and considering certain aspects as not at all subjects of international law. The democracies of developing countries, because of their colonial past, often insist on non-interference in their internal affairs, particularly with regard to human rights standards or their particular institutions, but often strongly support international law at the bilateral and multilateral levels, such as the United Nations, and in particular with regard to the use of force. disarmament obligations and the terms of the Charter of the United Nations. Most people never need to interact with international law. Those who interact with international law are part of the legal team of a large company or are victims of international human rights violations who seek asylum in safer countries. A nation, to be recognized as such by other nations, must be independent of foreign control and willing to live under international law. Formal or de jure recognition of a nation is irrevocable. It remains in force regardless of changes in territory, population, and social or political organization, unless the changes destroy the identity of the nation. Thus, the loss of much of its territory after the First World War did not destroy Turkey`s identity; but Austria-Hungary ceased to exist as a nation.
Belligerent groups and de facto governments – that is, governments that are actually in power, but do not have full legal authority, can be recognized as such until they demonstrate stability and a sincere intention to respect international law. International laws apply to governments. It is up to each state government to implement and abide by international laws. The laws of a country apply to citizens and other persons residing in the country. However, it is up to the governmental authority of the country to apply international law and respect its agreements with other countries concerned. The set of rules and customs that guide sovereign states in their relations with each other is called international law. It is based only on the mutual consent of sovereign states, and it is effective, either because the nations of the world recognize that it is in their interest to accept it, or because stronger nations are able to impose their views on the weaker. The Charter of the United Nations codifies the main principles of international relations, from the sovereign equality of States to the prohibition of the use of force in international relations. Grotius inspired two nascent schools of international law, the naturalists and the positivists.
In the first camp was the German jurist Samuel von Pufendorf (1632-94), who emphasized the supremacy of natural law over states. His 1672 work, De jure naturae et gentium, expanded Grotius` theories and established the natural law of reason and the secular world, asserting that it governed only the external actions of states. Pufendorf challenged the Hobbesian notion that the state of nature is a state of war and conflict, arguing that the natural state of the world is indeed peaceful, but weak and uncertain without respect for international law. The action of a state consists in nothing more than the sum of the individuals within that state, by which the state is obliged to apply a fundamental law of reason, which is the basis of natural law. He was one of the first scholars to extend international law beyond the European Christian nations and to advocate its application and recognition among all peoples on the basis of a common humanity. The law of the sea is the area of international law that governs the principles and rules governing the relations between States and other entities in ocean affairs.  It covers areas and issues such as navigation rights, marine mineral rights and the jurisdiction of coastal waters. Maritime law differs from Admiralty law (also known as maritime law), which concerns the relations and conduct of private entities at sea. Some sovereign rights may be surrendered by treaty. When a nation renounces its right to war, it becomes neutral, and when it renounces its right to exclude foreigners, it becomes international. In contrast, positivist writers such as Richard Zouche (1590-1661) in England and Cornelis van Bynkershoek (1673-1743) in the Netherlands argued that international law should be derived from actual state practice rather than from Christian or Greco-Roman sources.
The study of international law has moved away from its fundamental preoccupation with martial law and has moved towards areas such as the law of the sea and trade treaties. The positivist school used the new scientific method and, in this respect, was in line with the empiricist and inductive approach to philosophy that prevailed in Europe at the time. International lawyers have the opportunity to make a difference in the world. International treaties and agreements have the potential to do a great deal of good. They can help improve and increase trade between nations. They can help prevent wars. International lawyers can make agreements that prevent and end slavery. When wars occur, international rules of war can reduce the suffering of civilians and prisoners of war. For lawyers who want to do a lot of good internationally, international law can be a good choice. The Historical Archives of the Médiathèque de droit international is a unique resource for teaching, studying and researching the main legal instruments relating to international law.
The field of international law covers a wide range of issues of international concern, such as human rights, disarmament, international crime, refugees, migration, nationality issues, treatment of prisoners, the use of force and war. One of the complex issues of international law is that of sovereignty. It is the idea that the state comes first and that a state is not subject to the rules of another country or entity. It is the idea that one country cannot tell another country what to do. State sovereignty is a relatively new concept in history that developed as more and more governments organized themselves into states in the 18th and 19th centuries. General principles common to national legal systems may constitute a secondary source of international law. There are situations in which neither treaty nor customary international law can be applicable. In such cases, a general principle may be invoked as a rule of international law.