Sources of International Law

“International law grants rights to all human beings, not only to citizens” – Kofi Annan, former secretary of United Nations. 

This implies that all human beings have the right to be treated with dignity and respect by virtue of them being humans. The dignity and respect are conferred to people through the enjoyment of all human rights and are protected through the rule of law. The international law for all reasons is the custodian of rule of law. It is very intriguing to question the existence of international law as there is no formal parliament or the concept of legislation attached to it which overlooks the working of International Law. It is not that simple to take in principles from the national legal system to the international system, as at each stage the evolution is very different. The international community comprises 192 nations whose combined efforts contribute to the starting point of formation of international law. These decentralised bases of actions have primarily 5 sources, as per the Statute of the ICJ, Art. 38 [1] which are as follows:

a)     Treaties between the states

b)    Customary international law derived from the practice of states

c)     General principles of law

d)  Judicial pronouncements and the penned down words by the international law acclaimed specialist

Hugo Grotius [2] was born in 1583 in the Netherlands. He has been recognised as the father of international law as he retrained the theoretical distinction between a just and unjust law and considered justice essential.

Treaties between States

The term “treaties” which signifies as a form of agreement between states refers to protocols, and conventions between the states. It can sometimes also exist between states and the international organizations. Pacta sunt servanda [3] requires all states that are parties to honour their respective treaties. Therefore, treaties are often described as the sources of obligation arising under law. If a large number of states are involved in such a type of negotiation, the customary laws are mostly written. Although these were the unwritten laws previously. When a large number of states agree upon a treaty, it forms an important state practice. In this regard, important laws relating to terrorism, peace, diplomacy and war and other common areas concerning states were made. The year 1945 witnessed important changes due to the adoption of numerous treaties.

Vienna Convention on the Law of Treaties, 1969 is a striking example of a case in which a treaty provision of the existing law is intended to be codified notwithstanding that less than half the States in the world are parties to it. Its main provisions are considered as codifying customary law. Therefore, it is applied to all states irrespective of the fact whether they are parties to the convention or not. In today’s scenario, all treaties are contracts between their party members. Some also have an effect on the general laws.

 Customary International Law

These are the most useful and the oldest set of binding rules for all the states. There is no evidence of any written sources attached to these laws. An example for this is: states are required to grant immunity to a visiting head of state. There are two prime elements attached to it:

  1. There must be consistent and widespread state practice
  2. There must be belief in the legal obligation

Amy new addition to the customary laws must consider both the aspects of elements, else it cannot be created. Though there are many controversies regarding the opinio juris aspect. Some consider the real opinio juris is a belief not in obligation but in right. In the present scenario regarding the customs, opinio juris combined with its enough practice is considered for any new rule. The “persistent objector” principle binds the states.

General Principles of Law

Though treaties between states and customary laws constitute to be the most important but other sources cannot be ignored. The source is the third source after conventions and customs. There has not been any consensus reached regarding the origin of general principles of law. Some researchers have mentioned it being originated from natural law. Others regard them as stemmed from the positive law. The general principles of law are not formally mentioned in the judgements rather it represents the widely accepted legal systems of an organization or a nation. For example: Barcelona Traction Co. case (1970). The general principles of law are widely recognised as a primary source because of its validity across all kinds of human societies.

It becomes imperative to acknowledge the role played by general principles as no legislation provides answers to every question. Therefore, principles that enable decision-makers and members. There are at least four functions that “General Principles” fulfil as a source of international law, that are as follows:

a)     It acts a source of interpretation for conventional and customary international law

b)    A way for developing new norms of conventional and customary international law

c)     An additional source to conventional and customary international law

d)    A modifier of conventional and customary international rules.

Some jurists say the main function of general principles of law is of a safety-valve to be kept in reserve rather than a source of law of recurrent application. Positivists view that there exist no lacunas in international customs and conventions because the only international law that exists is that which has been posited. Therefore, there is no need for general principles.

Judicial Decisions

Article 38(1)(d) refers to judicial decisions source for ascertaining the rules of law.  Contrary to the situation in common law countries, there is no doctrine of binding precedent in international law.  The Statute of the ICJ entails that a decision of the Court is not binding on anyone except the parties to the case (Article 59). However, the ICJ involves time and again to its own past decisions.

Article 38(1)(d) does not separate between decisions of international and national courts. The former is considered more authoritative evidence of international law on most topics (though not those which are more commonly managed by national courts, for example the law on sovereign immunity). But decisions of a State’s courts are a part of the practice of that State and can contribute to the formation of customary international law.


The writings of international lawyers may also be a persuasive and authoritative guide to the content of international law but as they are not creators of law there is an apprehension in taking a passage from a book or article and assuming it reflects the content of international law.

International law is holistic in its approach and is an amalgamation of both primary (treaties, customs and general principles) as well as secondary sources (Judicial writings and teachings). State is a key part of international organization in the context of international law. According to Article 1, Montevideo Convention, [4] the state is composed of a defined area, its population, government and ability to enter relationships with other states. International organization is based on cooperation between states with permanent organs upholding common aims to ensure peace.

Most of the statutes of international law were drafted at a time when about 40 nation states comprised its anarchical system. The most important opinion was through scholarly knowledge. While today the feasibility of scholarly knowledge exists but many such writings do not provide a very appropriate teaching. Political overtones have overshadowed the intellectual writings, so it may not always be correct to focus on these as the prime ‘sources of law’. There are so many cross viewpoints regarding the teachings within the ambit of Article 38 that it can very easily confuse people. Many regard international law as soft law. Some areas require improvement as per the requirements of the current scenario. Article 38 goes a long way in shaping the framework of international law. As the society is progressing, this needs to be checked so that political relations do not create irregularities. Turning a blind eye to these issues might add actions which might question the dynamic international relations.


Every legal aspect has its innate origin in some stretch of jurisprudence. International law being not an exception it too has sources. Analysing sources becomes imperative to comprehend as it depicts the history of the law. Hugo Grotius is regarded as the father of international law. Article 38(1) of the Statute of the International Court of Justice illustrates the sources of international law. The ambit of international law is wide. It covers environmental goals, protection of human rights, child rights and many more. The United Nations (UN) is an embodiment of peaceful co-existence and universal brotherhood since the time of its foundation. Today many countries in the world are a part of the UN. Today the very character of intercontinental law is rooted in its relationship with all the political motivations, behavioural patterns and concepts of identity of states. However, to identify the expanse to which intercontinental law remains to have crucial influence in the conduct of universe politics, it could be beneficial to analyze the development of the idea of international law pertaining to their historical and sociological framework. One of the most characteristic suppositions is of international law’s being a neutral, apolitical avenue. Thus, the central role of international rules in the world, today when chaotic conflicts and inequalities have sharply divided the world, has transformed into regarding a frequency of electric power, a requirement that is held by every individual and every society that ascribes to and believes in the tenets of democracy.


[1] The Statute of The International Court of Justice, 1945, s.38.

[2]Martine Julia Van Ittersum, Hugo Grotius: The Making of a Founding Father of International Law (Oxford Handbook Online, U.K, 2016).

[3] I. I. Lukashuk, “The Principle Pacta Sunt Servanda and the Nature of Obligation Under International Law” 83 American Journal of International Law 513-518 (1989).

[4] Montevideo Convention on the Rights and Duties of States, 1933, art. 1.


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