Authors: Niharika Mukherjee, University of Calcutta

Vanshika Gupta, VIPS, GGSIPU, New Delhi

Editor: Rahul Kumar Roy, Manipal University Jaipur


Public International Law is the anatomy of legalized directives, norms, and merits that pertains between supreme states and other organizations that are lawfully acknowledged as international actors. Public International Law may also be given diverse names such as "Law of Nations". The sources which get involved under Public International Law are Treaties, International Customs, General Principles of Law which are acknowledged by cultured kingdoms, the resolutions of governmental and lower courts, and educational writings.

These sources of public international law are the information and procedures out of which the statute and postulates are managed from the international groups. They have been determined by a scope of legislative and legitimate theories. The term "Sources of Public International Law" generally meant two things. Firstly, the definite information ascertaining the statutes relevant to a given multinational circumstances and Secondly, the legalized procedures generating regulations of basic implementation.

This article attempts to shed some light on the various sources of Public International Law such as Treaties, International Customs and General Principal of Law.


The Sources of Public International Law are generated by various diverse sources, as there is no intermediate cosmopolitan body that constructs public international law. The fundamental legalized organ of the United Nations is the International Court of Justice (ICJ). Every UN member states are ipso facto parties to the ICJ statute as stated, under Article 93 of the UN Charter. But, the UN Member states are not indispensable to propose any case to it excluding the case where they have sanctioned or guaranteed to do so. The ICJ solely has the authority to decide cases that expresses authorization to propose to it for resolution. The authorization further can take the shape of binding agreement or proclamations of extending opportunity. The sources of Public International Law are listed in Article 38 of the statute of the International Court of Justice.

According to this article, the sources of Public International Law are divided into two parts. They are:-

(i) Firstly, the primary sources that includes International Conventions, International Customs and General Principles of Law, and

(ii) Secondly, the secondary sources that are constituted by the resolution of Courts and the viewpoint of legal intellectuals.

In addition to this Article 38 states "ex aequo et bono" (equity) as a replacement source of Public International Law pertained by the court if the parties admit thereto. Along with these traditional sources, there are contemporary sources which include the act of universal institutions. Further, below are the three primary sources of Public International Law are described.


Treaties are the most patent origin of Public International Law. These are accordance presumed generally among sovereign states. Treaties may also be called a covenant, pact, protocol, agreement, charter, communication of discernment and interchange of letter. Treaties can be either multilateral or bilateral and dispense with a broad span of events. The treaties that systematize particular domain like the "Law of Diplomatic Relations" or the "Law of Sea" are the multilateral treaties which customarily captivates the attentiveness of those who contends with the enlargement of multinational law.

Few of these treaties have been utterly victorious. These have been approved by most states and have conducted firmness to the extent of international law synchronized by them. The Vienna Convention on Diplomatic Relations is likely the finest example of multilateral treaties which enjoins comprehensive involvement and approval. But such limited victory cannot personate the fact that lawmaking by multilateral treaties agonizes from serious drawbacks. The procedure is both inconvenient and prolonged.

Multilateral treaties are constructed through various stages. Firstly, contemplation by a specialist takes place like the International Law Commission. Secondly, a draft of the treaty is approved by a political party like the General Assembly of the United Nations. Then, finally, the text of the draft treaty is resolved in a State Conference. In due course the treaty will be sanctioned by separate countries directing to its approach into power.

Bilateral treaties also distribute as an implementation of lawmaking. Actually, definite regions of international law are fundamentally controlled by a sequence of bilateral treaties. It is evident that this method is neither methodical nor sophisticated.


It may be defined as practices that have been followed by a large number of States internationally, over a long period of time and regarded by them to be legally binding.

Customary law is binding upon all states irrespective of if they have ratified a treaty, which is unlike treaty law as it is only applicable to those states that are parties to a certain agreement and have ratified them.

Article 38 of the International Court of Justice Statute refers to an International Custom as "evidence of a general practice accepted as law". There are two elements to this definition: a general practice (usus) and its acceptance as law (Opino Juris). The two requirements that are necessary for a custom to become international custom laws are:

· General Practice- The first element (the behavioral or objective element) is the recurrent action or lack of action by States, which is indicated by activities such as official statements or conducts, court decisions and diplomatic behaviors or correspondence, legislative or administrative action,

· Opino Juris- The second element (the psychological or subjective element) necessitates the principle that a generally accepted practice is required to be made a legal obligation by the States.


General Principles of law are established by comparing municipal laws of different countries. Any Principle common to most countries' national legal system may also be applied in an international law context. When there is no provision in an international treaty or statute nor any recognized customary principle of international law available for application in an international dispute, the general principles of law can be used to "fill the gap."[1]

Examples of such general principles of law are laches, good faith, res judicata, and the impartiality of judges.[2]

Article 38(1) of the International Court of Justice Statute refers to "the general principles of law recognized by civilized nations" as a primary source of International Law, which is the third listed source after international customs and international conventions.

The origin of the general principles of law have been queried by various opinions. Some state them as being originated from the Natural Law while others regard them as originated from the national legal systems and have been transplanted to the international level by recognition.


It can be concluded that there are various sources of Public International Law such as treaties, International Customs, and General Principals of law. All of these sources are interrelated as often, one of these sources overlaps and interacts with other/ others.

Therefore, to understand these sources, they should be regarded and studied as a whole rather than in isolation.

[1] See, What are General Principals of International Law?

<> as visited on 25 August 2020

[2] See, General Principles of Law <> as visited on 25 August 2020

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