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This article has been written by Kavita Chandra, from Vivekananda Institute Of Professional Studies, affiliated to Guru Gobind Singh Indraprastha University, Delhi. She has discussed the meaning, need and relevance of International Law. For better understanding emphasis has also been laid on the difference between International Law and Municipal Law and the sources of International Law.


Law is the element of the society which helps to develop a framework within which rights and duties can be established. The world today requires a method where interstate relations can be conducted, and International Law fills this gap. The United Nations developed this body of International Law for the purpose of promoting international peace and security.

Countries come together to make binding rules that they believe will benefit their citizens. International Laws promote peace, justice, common interests and trade. States work together to strengthen International Law because it plays an important role in society. International Law is directly and strongly influenced by the writings of jurists and publicists, instructions to diplomatic agents, important conventions even when they are not ratified, and arbitral awards.

Definition of International Law

According to Oppenheim, International Law is a “Law of Nations or it is the name for the body of customary law and conventional rules which are considered to be binding by civilized States in their intercourse with each other.

Thus, International Law can be considered as treaties, set of rules and agreements between countries that are binding between them. International Law governs how nations must interact with other nations. It is extremely useful in regulating the issue of jurisdiction which arises when people trade among different States. The main purpose of International Law is to promote justice, peace and common interest.

Relevance and Function of International Law

International Law grew out of necessity. As International engagement increased, International Law expanded. International Law is the most convenient form of regulating world order in the present-day world. International Law aims to maintain international peace and security, which provide for fundamental rights, freedoms and human rights, to refrain the State from the use of threat or force against the territorial integrity of any other State, to provide for the right of self-determination to people, to solve International problems by achieving International cooperation, to use peaceful means for settlement of international disputes.

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Principles of International Law

International Law is based on the following two principles:

  1. Jus Gentium: These set of rules do not form part of a legal statute but mutually governs the relationship between two nations.
  2. Jus Inter Gentes: These refer to those treaties and agreements that are accepted by both countries mutually.

International Law provides effective means through which peaceful settlement of disputes can be done. It is mainly concerned with the rights, duties and the interests of the State.

Classification of International Law

International Law can be classified into two groups:

Public International Law

Public International Law is regulated by the treaties and globally accepted norms and customs which are included as State practice and opinio Juris. It regulates the relationship between those nations and peoples that are prone to be affected by a particular law as they are bound by these legal codes and rules.

Private International Law 

It regulates private conflicts between individuals rather than the States. It seeks to resolve disputes in the domestic municipal body which involves an issue revolving beyond its domestic jurisdiction. 

What are the sources of International Law?

The sources of International Law are treaties, custom, general principles of law recognized by civilized nations, judicial decisions and teachings of publicists.


The concept of treaty is based on pacta sunt servanda, which is a customary law principle which means promises must be kept. In a treaty, countries create their terms of rights and obligations out of their volition, thus it is very similar to a contract. Therefore, a treaty is a written agreement between two or more States which lays down the manner in which every State would act while doing dealings with other participating States. Sometimes, in place of treaties other terms such as charters, declarations, conventions and statutes are often used. However, there is a slight difference in meaning of these terminologies.


Custom is one of the primary sources of International Law. In International Law, it is considered to be of particular importance because of its decentralized nature. Two conditions are essential for an act of a State to constitute as custom:

  1. The first being the State practice itself, it is not necessary that the act of a State necessarily needs to be positive in nature. State practice should be extensive, uniform and consistent and prevail for at least such a period of time as would establish it as a recognized act of States. 
  2. The second essential is opinio juris, which means, the psychological belief of a State that its act is creating a legally obligatory position for itself. But it should be noticed that not every activity of a State would necessarily create binding rules of customary law. For instance, if a particular pattern is used by the State on a particular issue in the General Assembly, it is reflective of the maxim opinio juris.

General Principles of Law

As in International Law there is no cohesive body for legislating laws or any Court that has the power to set precedents, thus it is relatively undeveloped as compared to the Municipal Law. Article 38 of the Statute of the ICJ provides for ‘general principles of law recognized by civilized nations’ as a source of law.

In the Chorzow Factory Case, the general principle of International   Law, it is the duty of a State to make reparations upon the breach of an international obligation, was recognized by the Permanent Court of International Justice. In the Corfu Channel Case, while referring to circumstantial evidence, the ICJ pointed out that ‘in all systems of law indirect evidence is admitted and its use is recognized by International decisions’. The principle of res judicata is too recognised by International Law.

Judicial Decisions

As per Article 38, judicial decisions are recognized as subsidiary means of determination of law. Article 59 of the Statute of the ICJ states that the decisions of the Court can only guide them but does not have any binding value on the Court and the court is authorised to apply the previous decisions of the court which are known as the evidence of International Law. Thus, the doctrine of stare decisis is not followed in International Law. 

ICJ through its case laws, advisory opinions and judges role-play a major role in the law-making process. One of the major examples of this was laid down in the case of Nicaragua vs. USA where the principle of the prohibition against the use of threat or use of force was recognised. This principle is now considered to be a part of Customary International Law.  In another case, that is, Alabama Claims arbitration, ICJ gave recognition to the peaceful settlement of international disputes. In this, judicial and arbitration methods were used in resolving conflict.

Writings of the Publicists

As per Article 38, teachings of the highly qualified writers of International Law such as Gentili, Grotius, and Vattel are considered as the subsidiary means of determination of law. The role of the writers is extremely significant in providing a structure and coherence in the field of International Law. Textbooks are used as a method of discovering law on any particular point and law cannot be created even by the writings of the most respected International Lawyers. As they provide an understanding and explanation of the principles of International Law these are considered as an evidentiary source of law. 

Can International Law be termed as a true law?

There has been a lot of controversy regarding this question. Some answered the question in negative while others in the affirmative. Some feel that International Law lacks the element of certainty, stability and predictability.

Not a true law 

John Austin, a leading English writer on Jurisprudence supports the view that International Law is not a law. As per him, International Law is a code of moral force and rules of conduct only. In his opinion, International Law does not have any sanction behind it and it doesn’t emanate from a law giving authority. He described International Law as the one consisting of positive International morality and opinions or sentiments which are followed by the nations as per their own wish.

Hobbes and Pufendorff are also of the view that International Law is not a true law as the law is not truly invested with true legal force and it is not backed by the command of a superior.

Holland is of the view that International Law is extremely different from ordinary laws as it is not supported by the State’s authority. As per him, the private law is writ large. He describes International Law as the vanishing point of Jurisprudence. He is of the view that as International   Law lacks sanction (which is the most important element of Municipal Law) it can not be kept in the category of true law. 

A true Law

Hall And Lawrence consider International Law as true law. According to them, International  Law is derived from custom and precedents which are a source of law and it is habitually treated like a certain kind of positive law.

Sir Frederick Pollock observed that for International Law to be binding upon the members,  the only essential conditions are the existence of political community and the recognition by its members of settled rules binding upon them in that capacity. International Law wholly satisfies these conditions. 

What is the difference between International Law and Municipal Law?

The basis of both laws is different in many ways.

  • Firstly, International Law is majorly concerned with the relation among States. Whereas Municipal Law controls the relationship between individuals and the State and between the individuals within a State.
  • Secondly, in the case of International Law, the law is not above the individuals but between the sovereign States and the States themselves create the law. In International Law, the States often disobey the laws or create laws as per their interests. Whereas in the case of Municipal Law, the law is deemed to be above the individuals, as is the case with the laws of most of the countries, the law is deemed to be above individuals. 
  • Thirdly, the sources of both laws differ. Article 38 of the Statute of the ICJ is considered as the most authoritative statement of the sources of law for the Public International Law. It states the sources of law such as customs, conventions, treaties, general principles of law recognized by civilized nations and judicial decisions and teachings of highly qualified publicists. Whereas in the case of Municipal Laws there is a hierarchy of laws which determines, which legal commandment is more authoritative than others. For instance, in many countries, a hierarchy of courts is established wherein the judgments of higher courts are of more authoritative value and thus are relied upon by the lower courts.


International Law is a set of rules which are necessary in order to regulate the behaviour of nation-States towards each other so as to ensure peace and welfare of the International community. It helps in resolving disputes amongst States. International Law may influence internal laws too and may become a part of domestic law.

It is not necessary for International   Law to be codified into an agreement. There have been a lot of developments in the Modern International Law and the International Court of Justice is considered as the principal body responsible for upholding the tenants of International Law.



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