Customary International Law refers to international obligations arising from established state practices, rather than from formal written treaties or agreements. It is one of the primary sources of international law and is binding on all states, regardless of whether they have signed a treaty, provided they have not persistently objected to the custom. Here’s a detailed explanation: 1. Definition: Customary international law consists of rules and norms that have developed over time from the consistent and general practice of states, followed by them out of a sense of legal obligation (known as opinio juris). 2. Essential Elements: State Practice (Usus): There must be widespread, uniform, and consistent conduct by states over time. This includes actions by governments, legislation, court decisions, and diplomatic communications. Opinio Juris: States must follow the practice because they believe it is legally obligatory, not just out of courtesy, habit, or political expediency. 3. Examples of Customary International Law: The prohibition of genocide, torture, and slavery Rules of diplomatic immunity The principle of non-refoulement (not returning refugees to a country where they face harm) The law of the sea (prior to the codification in treaties like UNCLOS) 4. Importance: Customary international law plays a key role where no specific treaty exists. It fills gaps in international relations and ensures that even non-signatory states are bound by certain universal standards. 5. Application in India: Indian courts have recognized the role of customary international law in various judgments. As long as it does not conflict with Indian domestic law, customary international law can be applied in Indian courts. 6. Limitations: Proving a custom and the existence of opinio juris can be challenging. A state that consistently objects to a particular custom may not be bound by it (this is called the "persistent objector" rule). Conclusion: Customary international law is formed from the consistent and general practice of states, carried out with a belief that such practice is legally required. It is a vital source of international law and helps uphold global norms and standards, even in the absence of written agreements.