Morgenthau argues that no state should be forced to submit a dispute to an international tribunal, which would render the laws unenforceable and voluntary. International law is also not controlled, there are no enforcement agencies. He cites a 1947 U.S. opinion poll in which 75 percent of respondents wanted „an international police force to maintain world peace,“ but only 13 percent wanted that force to surpass the U.S. armed forces. Subsequent polls produced similar contradictory results.  The history of international law examines the development and development of international law both in state practice and in the understanding of concepts. Modern international law evolved from Renaissance Europe and is strongly linked to the development of Western political organization at that time. The development of European notions of sovereignty and nation-states would require the development of methods of inter-state relations and standards of conduct that would lay the foundations of international education law. In many areas, United Nations legal action has been innovative, addressing issues that take on an international dimension.
The United Nations is at the forefront of efforts to establish a legal framework in areas such as environmental protection, regulation of migrant workers, the fight against drug trafficking and the fight against terrorism. This work continues today as international law plays a more central role on a wider range of issues, including human rights and international humanitarian law. The Roman Empire did not develop international law, because it acted without regard for external rules in the treatment of territories that were not already part of the empire. However, the Romans formed urban laws that regulated the interaction between private Roman citizens and foreigners. These laws, called jus gentium (as opposed to ius civile, which governs interactions between citizens), codified certain ideas of fundamental justice and attributed certain rules to an objective and independent „natural law.“ These jus gentium ideas of equity and natural law have survived and are reflected in modern international law. The role of civil society is of particular importance when the dispute over an issue impedes State action. The Yogyakarta Principles on the Application of International Human Rights Law on Sexual Orientation and Gender Identity are a good example. Although adopted in November 2006 by 29 experts from just 25 countries, the 29 principles contained in the document – which relate to States` obligations regarding sexual orientation and gender identity – are becoming an internationally accepted reference point and are likely to guide future discussions. Many scholars agree that the fact that sources are arranged sequentially suggests an implicit hierarchy of sources.  However, the wording of Article 38 does not explicitly contain such a hierarchy and the decisions of international tribunals do not support such a strict hierarchy. In contrast, article 21 of the Rome Statute of the International Criminal Court clearly defines a hierarchy of applicable law (or sources of international law).
After the First World War, attempts were made to establish a new international law of peace, of which the League of Nations was considered one of the cornerstones, but this attempt failed. Indeed, the Charter of the United Nations (1945) reflects the fact that the traditional concept of State sovereignty remains the key concept of international law. However, as recent research has shown, ius contra bellum (the prohibition of war) has its roots in the legal and political discourse of the 19th century.  The relationship and interaction between a national legal system (domestic law) and international law is complex and variable. National law can become international law if treaties grant national jurisdiction to supranational courts such as the European Court of Human Rights or the International Criminal Court. Treaties such as the Geneva Conventions may require national legislation to be in conformity with the provisions of the Treaty. National laws or constitutions may also provide for the transposition or incorporation of international obligations into domestic law. Customary international law applies to all countries, whether or not they have formally consented to it. At the same time, all countries participate in the development of customary international law through their practices and decisions. When new rules appear, accept, reject, or modify them.
If most countries follow one rule, all others will be. Therefore, to do nothing is to accept. Nations that have done nothing may find themselves bound by international law that is not to their advantage. Nation-states follow the principle par in parem non habet imperium: „There is no sovereign power among equals.“ This is reaffirmed in Article 2(1) of the Charter of the United Nations, which states that no State shall be subject to another State. John Austin thus asserted that „so-called“ international law was devoid of sovereign power and therefore unenforceable, was not a right at all, but a „positive morality“ consisting of „opinions and feelings“. more ethical than legal.  International law provides the framework and criteria for identifying states as key actors in international law. Since the existence of a State presupposes control and jurisdiction over territories, international law deals with the acquisition of territory, the immunity of States and the legal responsibility of States for their conduct among themselves. International law treats the treatment of individuals within the borders of States in the same way. There is therefore a comprehensive regime that deals with collective rights, the treatment of aliens, refugee rights, international crimes, nationality issues and human rights in general.
It also includes the important functions of the maintenance of international peace and security, arms control, the peaceful settlement of disputes and the regulation of the use of force in international relations. Although the law is not able to prevent the outbreak of war, it has developed principles to regulate the conduct of hostilities and the treatment of prisoners. International law is also used to regulate issues related to the global environment, global commons such as international waters and outer space, global communications and global trade. In the modern world, international law is being challenged because of its inability to enforce its decisions. „treaty“ means an international agreement concluded in writing between States and governed by international law, whether enshrined in a single instrument or in two or more related instruments, and whatever its specific name.  The International Criminal Court (ICC) has jurisdiction to prosecute those who commit genocide, war crimes, and crimes against humanity. He will also be responsible for the crime of aggression if agreement is reached on the definition of such a crime. The ICC is legally and functionally independent of the United Nations and is not part of the United Nations system. Often extremely complicated, ICJ cases (fewer than 150 since the Court`s establishment from the Permanent Court of International Justice in 1945) can span several years and typically include thousands of pages of briefs, evidence and leading international specialist lawyers.
As of November 2019, 16 cases were pending before the ICJ. Decisions in other arbitration proceedings may or may not be binding depending on the type of arbitration agreement, while decisions arising from contentious cases heard by the ICJ are always binding on the States concerned.