International Law

International law is the set of rules that governs the relations among sovereign states. These rules deal with issues such as human rights, war, the law of the sea and outer space.


In modern times, it has been agreed that individual people and international organizations are also the subjects of International law with recognised rights and duties. Violations of these rules can be met with disapproval or coercive action, including sanctions or war.


International law is the body of legal rules, norms and standards that governs the relationships between states (public international law) as well as between non-state actors such as companies and individuals (private international law). These international laws are generally enforceable in international tribunals, courts or arbitration. International law can be found in a variety of sources, including treaties, conventions, agreements, declarations and customs.

International law has been around for centuries. Early thinkers like English philosopher Jeremy Bentham viewed it as a system of natural law that is independent of national customs and differences, and that guides peaceful interstate relations. The Dutch jurist Hugo Grotius secularized this idea, and created a body of law based on universal principles rather than local customs. He inspired two schools of thought that remain influential in modern International law, the naturalists and the positivists.

Today, there is a broad consensus that while international law cannot be enacted by any single state, it can be created and enforced through the efforts of multinational organizations, intergovernmental committees and international tribunals. Nations are often compelled to act in accordance with international law through economic and political pressures, but they are free to reject any treaty or agreement that they feel does not adequately protect their interests. However, a state that consistently violates the rules of the international system may be spurred on by other countries to do the same, and this could lead to an unintended chain reaction of escalating behavior that will undermine the value of the whole system.


There is a large spectrum of legal sources that compose international law. The major formal sources are treaties, custom and judicial decisions. Other formal sources include the general principles of law that derive from domestic or national law and the writings of publicists. These can be difficult to research and tend to overlap with other resources.

A few major legal texts have a canonical status and should be included in any study of the field. They are often written by major scholars from established empires and may have a particular perspective. These can be useful as a broad introduction to the field but should not be relied upon as a complete source of information.

Some treaties codify existing customary international law and can rise to the level of jus cogens (universal standards of international law) through acceptance by enough states. Other treaties are merely a contractual agreement between two or more parties. Judicial decisions and teachings of publicists are also important sources of international law. In many cases, a court like the ICJ will reference its own previous decisions in order to make a ruling. This is called stare decisis. Other courts and international organizations, such as the OSCE or the ICC, will refer to scholarly writings of well-regarded publicists. These are called secondary sources of international law.


Many areas of life are now touched by international law, including commerce (trade agreements), armed conflict (agreements about when one state may use force against another), human rights (which is set forth in several treaties and conventions), refugees, criminal laws, and the environment. Some people are not involved in international transactions at all, but still are affected by international law through the actions of others or by the existence of a body such as Interpol that works to prevent crimes.

In addition, most lawyers today are exposed to international legal issues in their professional work. The increasing number of businesses that operate across international borders and the globalization of economic and social activities increase the likelihood that a lawyer will encounter a complex or challenging international legal issue in his or her practice.

The international community is often at odds about how to apply international law. The arguments for and against using international law are often based on the benefits, costs, risks of harm, and trade-offs that may result from different applications of international law. For example, a quantitative impact evaluation of the effectiveness of an international law aimed at addressing global health challenges must consider whether the implementation of that law will lead to additional resources and incentives for the public or private sector to pursue similar interventions.


Sovereignty, the supreme power of a state within its territory, is one of the most fundamental concepts in international law. It is the basis for more specific rules of international law, such as the prohibition of force and the principle of non-interference.

In the contemporary sense, sovereignty focuses on a state’s exclusive authority over its national territory and excludes any external intervention in that domain. This modern concept is generally associated with the treaty of Westphalia in 1648, which spelled out the delimitation of secular sovereignty and established a legal principle limiting the right to invade another State’s territory.

The 20th century saw the rise of negative conceptions of sovereignty, which viewed the power of States as corrupt and susceptible to abuses. These developments have led to the establishment of a considerable body of international law limiting the sovereign power of States. These limitations are usually based on the notion of consent or autolimitation, which imply that a state cannot be forced to accept new laws without its express or implicit consent.

Today, the concept of sovereignty is constantly challenged in various contexts. There are growing debates concerning whether developing or third world countries enjoy the same plenitude of sovereignty as developed powerful States. There are also challenges in ensuring that international law includes post-colonial realities and respects sovereignty.