International law and municipal law are two separate legal systems that interact with one another. International law is a set of rules and principles that govern the relations between states and other international actors. It is based on the idea that states are sovereign entities that have the power to make and enforce laws within their own borders, but that also have certain obligations to respect the rights and interests of other states. International law can be found in a variety of sources, including treaties, customary international law, and general principles of law.

Municipal law, on the other hand, refers to the legal system of a particular state or country. It is the domestic law that applies within the jurisdiction of a particular state. Municipal law is typically created and enforced by the government of that state, and it can include laws related to criminal and civil matters, as well as constitutional law and administrative law.

The two legal systems are distinct, but they also intersect in various ways. International law can serve as a source of municipal law, and the principles of international law can be incorporated into domestic legal systems through treaties and customary international law. For example, a state may ratify an international treaty that contains certain provisions related to human rights. Once the treaty is ratified, those provisions become part of the state’s domestic law, and the state is obligated to comply with them. Similarly, states can be bound by the principles of customary international law, which are rules that have become widely accepted and followed by states as a matter of practice.

Additionally, municipal courts may be called upon to interpret and apply international law in certain cases. For example, a municipal court may be asked to rule on whether a state has violated its obligations under an international treaty. In such cases, the court must consider both the domestic law of the state and the principles of international law in order to make a decision.

The relationship between international and municipal law can also be seen in the role of international tribunals and courts. International tribunals and courts are often established to resolve disputes between states or to hear cases involving individuals or organizations that are accused of violating international law. These tribunals and courts may apply both international law and the law of the state in question in order to make a ruling.

Overall, the relationship between international and municipal law is complex, but it is important for the proper functioning of the international legal system. International law provides a framework for states to interact with one another and to respect the rights and interests of other states, while municipal law allows states to govern themselves and to protect the rights of their citizens. The interaction between the two legal systems helps to ensure that states are held accountable for their actions and that individuals are protected from abuses of power.

However, the relationship between international and municipal law is not always harmonious. There may be conflicts or inconsistencies between the two legal systems, which can lead to confusion and uncertainty. In such cases, it is important for states and courts to work together to find a resolution that is consistent with both international and municipal law.

There have been several landmark judgements in India related to the relationship between international law and municipal law. Some examples include:

1. The Keshavananda Bharati case (1973): This case dealt with the interpretation of the Indian Constitution and the relationship between fundamental rights and the power of the government to amend the Constitution. The Supreme Court of India held that the power of the government to amend the Constitution is not absolute and that certain fundamental rights cannot be amended.
2. The Narmada Bachao Andolan case (2000): This case concerned the construction of a dam on the Narmada River and the potential displacement of thousands of people. The Supreme Court of India held that the government had an obligation to protect the rights of the people affected by the dam, including the right to life and the right to livelihood, as well as the principles of sustainable development.
3. The Arulmozhi case (2008): This case dealt with the interpretation of the Indian Extradition Act and the relationship between international law and domestic law. The Supreme Court of India held that the Extradition Act must be interpreted in accordance with international law and that the government must consider the human rights of the person sought to be extradited.
4. The Jallikattu case (2014): This case dealt with the traditional Indian practice of Jallikattu, a bull-taming sport, and the relationship between animal welfare and cultural rights. The Supreme Court of India held that the practice of Jallikattu was in violation of animal welfare laws and that the government must take steps to protect the welfare of animals.
5. The Kulbhushan Jadhav case (2017): This case dealt with the interpretation of the Vienna Convention on Consular Relations and the rights of a foreign national to consular access. The International Court of Justice (ICJ) held that India had violated the Vienna Convention by denying consular access to Jadhav, an Indian national arrested in Pakistan, and ordered Pakistan to provide effective review and reconsideration of his conviction and sentence.

These are some examples of landmark judgements in India that have dealt with the relationship between international law and municipal law. These cases illustrate the important role of the judiciary in interpreting and applying international law in the domestic context, and demonstrate how courts can balance the competing interests of different legal systems.

In conclusion, the relationship between international and municipal law is complex but necessary for the proper functioning of the international legal system. The interaction between the two legal systems helps to ensure that states are held accountable for their actions and that individuals are protected from abuses of power. However, the relationship between international and municipal law is not always harmonious, and in such cases, it is important for states and courts to work together to find a resolution that is consistent with both international and municipal law.