The world today is a globalised world contrary to the world few years back. This leads to implementation of international law. The international law, today, is full of dissension. International law is derived majorly from customary law. Customs are unwritten sources of law. They have two main elements: opinion juris and state practice. This paper discusses the roleof domestic courts in determining customary international law. The Indian Judiciary and the Indian Constitution follow the customary law knowing its importance.The research paper begins with explaining the definition and core elements of customary law. Customary law is superior to treaty laws when there are no conventions based on treaty law. Life is changing at a rapid speed and customary law is taking the place of treaties. Customary law in 21st century is diverse. Even the drafters of international law had no clear idea before they framed it. This is the reason customs have become a major source of international law. The Indian Constitution moves in lines with the International Law. The International Law helps to safeguard the human rights. Also, theUniversal Declaration of Human Rights, Vishakha Guidelines and the Vienna Convention on Law of Treaties revolve around the customary law. The paper is going to explore the notion of domestic application of international customary rules and important prerequisites for their application: domestic validity of a customary rule and its status with respect to other domestic norms. The paper will also discuss various cases of India where domestic courts applied international customary rules.
