It is simpler to identify the source of law inside a domestic legal system Finding the origins of international law, however, is not so simple. However, Article 38(1) of the Statute of the International Court of Justice provides access to the most reliable sources of international law. Though Article 38(1) is technically limited in application to the International Court of Justice, since the role of the court is to resolve disputes submitted to it in accordance with international law and each member of the United Nations is ipso facto member, it is generally agreed that Article 38(1) enumerates the main sources of international law.

How many sources of International Law are listed in Article 38(1) of the Statute of International Court of Justice?

Four

A source of law within a domestic legal system is easier to determine. Within the domestic system it is considered as something which is not too difficult a process, where one may look at the various legislations or statutes provided for by the legislature and if there is a lacunae in the statute then decisions of the domestic courts. But, it is not so easy to pinpoint the sources of International law. Yet, the most authoritative source of international law is Article 38(1) of the Statute of the International Court of Justice, which provides that when a court which deals with disputes relating to international law, it shall apply :
1."International conventions, whether general or particular, establishing rules expressly recognized by the contesting states,
2. International custom, as evidence of general practice accepted by law
3. The general principles of law recognized by civilized nations
4. Subject to provisions of Article 59, judicial decisions and teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of international law”.

Thus, there are 4 sources of international law.