International law, also known as public international law, is a set of rules and principles that govern the relations between states and other international actors. These rules and principles are derived from a variety of sources, including treaties, customary law, and general principles of law. Understanding the sources of international law is essential for understanding the nature and scope of international law, as well as the ways in which it is created, interpreted, and enforced.

The first and most important source of international law is treaty law. Treaties are legally binding agreements between states that are created through negotiation and consent. These agreements can take many forms, including conventions, protocols, and covenants. They cover a wide range of subjects, from human rights to trade and investment. Treaties are considered to be the primary source of international law because they are created through the consent of states and are binding on the states that have ratified them.

Another important source of international law is customary law. Customary law is a set of unwritten rules and practices that are considered to be legally binding on states because they are based on the consistent and widespread practice of states, accompanied by a sense of legal obligation. Customary law can include both general customs and specific customs. General customs are those that are widely accepted and applied by states, such as the prohibition on the use of force and the principle of non-interference in the internal affairs of other states. Specific customs are those that apply to a specific subject area, such as the law of the sea or the law of diplomacy.

A third source of international law is general principles of law. General principles of law are those that are recognized by the legal systems of the world, such as the principle of good faith and the principle of reasonableness. These principles are considered to be a source of international law because they are widely accepted and applied by states, and they are considered to be a fundamental aspect of the legal systems of the world.

In addition to these traditional sources of international law, there are also a number of other sources that have gained increasing importance in recent years. These include the decisions of international courts and tribunals, such as the International Court of Justice and the International Criminal Court, as well as the opinions of legal scholars and the resolutions of international organizations such as the United Nations. These sources are considered to be important because they provide guidance on the interpretation and application of international law, and they help to ensure that international law remains responsive to the changing needs and expectations of the international community.

There have been several landmark judgements on international law in India. Some of the notable ones include:

1. The ICJ judgement in the case of the “Berubari Union and Exchange of Enclaves” (1960), India and Pakistan sought the Court’s opinion on the legality of the proposed transfer of certain enclaves between the two countries. The Court found that the transfer of the enclaves would not be in violation of international law.
2. The ICJ judgement in the case of “Kulbhushan Jadhav” (2019) was a high-profile case in which India challenged Pakistan’s decision to sentence an Indian national to death for alleged espionage. The court found that Pakistan had violated the Vienna Convention on Consular Relations by failing to notify India of Jadhav’s arrest and by denying him consular access.
3. India v. Italy and Marine Salvatore Girone (2015) was a case in which India sought the enforcement of an arbitral award against Italy in a dispute concerning the arrest and detention of two Italian marines. India’s position was that the marines’ detention was in accordance with international law while Italy’s position was that the marines should be immune from prosecution. The Supreme Court of India held that the marines were not immune from prosecution under Indian law, and that the award was enforceable under Indian law.
4. “Air India v. Nargesh Meerza” (1981) was a case where the Indian Supreme Court held that the act of hijacking an aircraft is a crime under international law and India was under an obligation to prosecute the offenders.
5. “S.S. Lotus (France v. Turkey)” (1927) was a case before the Permanent Court of International Justice, in which Turkey was accused of having caused the collision of the French steamship Lotus with a Turkish steamer. The Court held that Turkey was responsible for the collision under the rules of international law, and that Turkey was liable to pay damages to France.

In conclusion, the sources of international law are varied and diverse. Treaty law is considered to be the primary source of international law because it is created through the consent of states and is binding on the states that have ratified it. Customary law is another important source of international law, as it is based on the consistent and widespread practice of states, accompanied by a sense of legal obligation. General principles of law are also considered to be a source of international law, as they are recognized by the legal systems of the world and are considered to be a fundamental aspect of the legal systems of the world. Additionally, other sources such as the decisions of international courts and tribunals, opinions of legal scholars and the resolutions of international organizations also play an important role in shaping and interpreting international law.