Theories of International Law and Municipal Law

Updated: Aug 17, 2020


Nothing is more essential in International law than having a comprehensive understanding of its relationship with the Municipal law of a State.

This article will be talking only about the theoretical aspect of International law on Municipal law however, there are two governing principles of International law relating to the Municipal application of treaties, and they are:

1. Article 27 of the Vienna Convention on the Law of Treaties:

Prohibits the states from invoking its Municipal law as its justification for non-obligation towards the performance of treaty.

2. Article 8 of the Universal Declaration of Human Rights and Fundamental Freedoms:

Every individual is vested with the right to an effective remedy by the tribunal which is competent to hear, for violations of fundamental rights granted by the constitution or by any other law.

The significance of the theoretical aspect of this topic can never be overrated as the question regarding the consideration of limits between International law and a state’s Municipal law is usually argued among those who practice International law. Apart from the theoretical aspect of the relation between International law and Municipal law there exist a practical problem in a State’s Municipal courts that, as to what extent the Municipal courts of a country give effect within its jurisdiction to the rules and principles of International law, both where the rules and principles are in conflict with Municipal law and not in conflict with Municipal law.

Theories on the relationship between International law and Municipal law.

The two principal theories of the relationship between International law and Municipal law are known as Monism and dualism. As per the beliefs of Monism, International law and state’s Municipal law are two components but complementary aspects of one single system. According to dualism, they are entirely distinct and different legal systems on their own. International law has an intrinsically different character from that of the state law because in International law a large number of the State’s legal system are involved, the dualist theory is sometimes known as the pluralistic theory.

To know the relationship between International law and Municipal law, it is crucial to understand what these two laws actually are. The rules and regulations which deal with the conduct of states is known as International law. In order to simplify, we can say, set of principles which the states can invoke or apply while dealing with other states or international organizations. On similar grounds, it is also called “the law of the nations”. On the other hand, Municipal law is known as the internal law of the land.

1. Monistic theory:

International law operates only at the International level and the Municipal law operates only on its local jurisdictional limits. However, the advocates of natural law believe that Municipal and International law form a single legal system, this approach is commonly known as Monism.

To have a better understanding of this topic it is crucial to understand what natural law is; natural law is something that exists in isolation with the positive law. As the name suggests, it is determined by nature, the law of nature is objective and universal in nature. From the time of inception, natural law is referred to analyze human nature to deduce moral behaviour from nature.

The argument from the side of a Monist is pretty simple, they believe Municipal law and International law if looked together is nothing but a single system. Modern writers who favour the monistic approach endeavours that a major portion of their views are based on a strictly scientific analysis of the Municipal structure of legal systems.

In a true monist country, there is no need for the translation of International law into Municipal law. Once the state gives assent to the treaty, it automatically gets incorporated in its municipal law. This act of giving assent to an International treaty or obligation will immediately incorporate international principles into states’ Municipal law, (this is inclusive of customary International law.)

International law can be applied by a Municipal Court and can be invoked by citizens, contingent on the fact that the international law is translated into the state’s Municipal law. A municipal court can declare a law as unconstitutional if it contradicts international principles.

In a true monist state, if a national law contradicts International law then it becomes null and void, no matter whether it is of constitutional nature or not. For example, a state gives assent to the Convention on the Rights of Persons with Disabilities, however, a few of its national laws are in contradiction with the conventions rights of the individuals who suffer from a disability. Then, a citizen of that country, who is not getting deprived of the rights conferred by the treaty, can ask the national courts to apply the treaty.

In a Monist State, the International law gets automatically accepted and the contradicting part automatically gets translated away the moment the State ratifies the treaty.

Kelsen: Grundnorm theory

For Kelsen, International and Municipal law is nothing but “manifestations of a single unit of law”. Kelsen's belief in the supremacy of International law is the result of his "basic norm", which states that: 'states should behave as they customarily have behaved'.

International law is supreme in nature as it represents a legal order which is higher than Municipal laws, it is because the International law is derived from the state’s practice, on the other hand, the Municipal law gains its power from the state’s internal affairs.

Once it is accepted that International law is a system of rules of a legal character, it becomes impossible according to kelson to deny that the two systems constitute a single system.

The theory of International law and Monism doesn’t have any halfway house. Kelson observed natural law and International law as a single and coherent system. According to him, International law is placed at the top of the pyramid (as per his grundnorm hypothesis).

2. Dualist theory:

Unlike Monists, dualists have stressed the difference between International law and Municipal law and have argued for the adoption of international treaties in the Municipal law of the State. According to dualists, in absence of this adoption by the State, the International law will not exist as a law.