Sources of International Law

The sources of international law refer to the origins from which legal rules and obligations in the international system are derived. Article 38(1) of the Statute of the International Court of Justice (ICJ) outlines the primary and subsidiary sources recognized in public international law.

1. Treaties (Conventions)

Treaties are written agreements between states that are governed by international law. They may be bilateral (between two states) or multilateral (among many states).

• Binding upon the parties who consent to them.
• Examples: UN Charter, Geneva Conventions, Paris Climate Agreement.

2. Customary International Law

Custom consists of practices and behaviors consistently followed by states out of a sense of legal obligation (opinio juris).

• Unwritten source but legally binding.
• Requires general and consistent state practice + belief in legal obligation.
• Examples: Rules on diplomatic immunity, non-refoulement principle.

3. General Principles of Law Recognized by Civilized Nations

These are fundamental legal principles common to major legal systems across the world, used when treaties or custom do not apply.

• Examples: Principles of equity, good faith, res judicata, and due process.
• Help fill legal gaps in international law.

4. Judicial Decisions

Judgments from international tribunals and courts, especially the International Court of Justice (ICJ), are considered subsidiary means for determining rules of law.

• Not binding as precedent, but highly persuasive.
• Examples: Nicaragua v. USA (1986), North Sea Continental Shelf Case (1969).

5. Teachings of Highly Qualified Publicists

Scholarly writings from prominent international law experts also serve as a subsidiary source of law.

• Used to interpret and support legal arguments.
• Recognized by ICJ under Article 38(1)(d) as a source of legal understanding.

6. Hierarchy of Sources

While there is no strict hierarchy, treaties and customary international law are generally treated as the most authoritative sources. General principles and subsidiary sources (judicial decisions and teachings) assist in interpretation and application.

7. Conclusion

The sources of international law provide the legal foundation for relations among nations. Understanding these sources is essential for interpreting obligations and resolving international disputes within the legal framework established by the global community.

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Published by Pavan Law Chambers | Public International Law Series