Understanding the Sources of International Law
International law, the body of rules governing relations between states, derives its authority from several recognized sources. For competitive exams like the LSAT India and for aspiring international law students, a firm grasp of these sources is fundamental. This module will explore the primary sources: Treaties, Customary International Law, and General Principles of Law.
1. Treaties: The Written Agreements
Treaties are the most direct and formal source of international law. They are written agreements between states (or between states and international organizations) that are binding on the parties involved. Think of them as international contracts. Treaties can cover a vast range of subjects, from trade and environmental protection to human rights and the laws of war.
2. Customary International Law: The Unwritten Rules
Customary international law is formed by the consistent practice of states, coupled with a belief that this practice is legally required (opinio juris). Unlike treaties, it is unwritten and emerges organically from state behavior over time.
3. General Principles of Law: Filling the Gaps
General principles of law are fundamental legal principles that are common to the major legal systems of the world. They serve to fill gaps where treaties or customary law may be silent or insufficient.
Interplay and Hierarchy
While Article 38 of the ICJ Statute lists these sources, it does not establish a strict hierarchy. However, in practice, treaties are often considered the most authoritative source when they exist and are applicable. Customary law fills the gaps and can even inform the interpretation of treaties. General principles act as a subsidiary source, providing foundational legal reasoning. It's important to note that these sources are not mutually exclusive and often interact.
Treaties, Customary International Law, and General Principles of Law.
State practice (usus) and opinio juris (belief that the practice is legally required).
Remember: While treaties are written and explicit, customary law is unwritten and inferred from state behavior. Both are crucial for understanding the landscape of international legal obligations.
This diagram illustrates the relationship between the primary sources of international law. Treaties are formal written agreements. Customary law develops from consistent state practice and belief in its legal necessity. General principles are fundamental legal concepts common to national legal systems, often used to fill gaps. The diagram shows how these sources contribute to the body of international law, with treaties and custom often being the most direct sources, and general principles serving a foundational role.
Text-based content
Library pages focus on text content
Learning Resources
This resource from the International Committee of the Red Cross explains the primary sources of international law, including treaties, custom, and general principles, with a focus on humanitarian law.
The foundational text that enumerates the sources of international law that the International Court of Justice shall apply in deciding disputes.
A comprehensive overview of customary international law, its definition, formation, and examples, from Wikipedia.
The full text of the Vienna Convention on the Law of Treaties (1969), the primary treaty governing treaties between states.
A video lecture providing a clear and concise introduction to the sources of international law, suitable for exam preparation.
An academic chapter delving into the concept and application of general principles of law within the international legal system.
A scholarly article discussing the relationship and interplay between treaties and customary international law.
A blog post offering tips and insights for preparing for the international law section of the LSAT India exam, including key concepts.
An insightful article from the American Society of International Law discussing the significance and function of general principles in international legal reasoning.
A blog post from E-International Relations providing a straightforward explanation of the core sources of international law.