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.

The reason why dualists have this view is that they believe International law and Municipal law are two different aspects of law and it would be unreasonable to take the two as a unity. As per their belief, International law and Municipal law are two distinct and independent systems in itself.

In a dualist State, it is of utmost importance that International law has to be drafted in its Municipal law in order to give it an effect. Apart from drafting it is the duty of the state to omit those laws which contradict the newly adopted International law.

If a dualist State ratifies a treaty or a convention but does not create a law explicitly incorporating the treaty, then their act of non-incorporation violates the International law. If the State has not incorporated the principles of a treaty as per its local laws which it has ratified earlier in the International sphere then, neither the citizens of that country can invoke the International laws nor the courts can give its decisions based on the principles of that treaty.

The United Kingdom is a country in which a dualist approach is dominant. International law becomes the national law in the UK only if it is translated.

Hersch Lauterpacht on Dualism

Judge Lauterpatch was an advocate of natural law, he accepted that International law observes the precepts of natural law.

For Lauterpacht, International law is more superior than municipal law, the rationale behind this view is because it offers the guarantee rights for the individuals notwithstanding anything from which state he belongs to. As per Lauterpacht, the hierarchy of legal orders was:

  1. Natural law

  2. International law

  3. Municipal law.

For him, whether it is International law or Municipal law, it is the individual who is the definitive unit of all law. He answered a few fundamental questions of international law philosophy regarding the concept and origin of international law.

He Criticized the doctrine of Heinrich Triepel's doctrine of an international legal obligation, meanwhile agreeing with Kelsen that the binding force of law cannot be derived from the individual or common will of the states.

For Lauterpacht, international law is for the states and not for governments. For him, the international community was a community of individuals, whose will is expressed by the states.

Triepel on dualism

Triepel treated the two systems of State law and International law as entirely distinct in nature. For him, the International and Municipal law exist as two separated, distinct sets.

Triepel made the following contentions on the relationship between International law and state law:

  • Firstly he contended that International law and Municipal law differ in the particular social relations that they govern; State law deals with the individuals and International law regulates the relations between States.

  • Secondly, he argues that their juridical origins are different; the source of Municipal law is the will of the State itself, the source of International law is the common will of States.

  • There exist differences in: subjects, sources and content, also, it requires ‘transformation’ of International law into Municipal law to make International law binding on Municipal authorities.

Triepel accepted that the basic will of the States was the premise of the legitimacy of International law; he also pointed out that it heavily relies upon the agreements between States, which not only includes treaties but custom too and the common will was the most important and inventive source of International law.

The problem of “lex posterior”

In a dualist country, International law must be translated into Municipal law, and the existing Municipal law which contradicts International law must be "translated away". The international law must be translated into municipal law in order to conform to International law. However, the need for translation causes a problem with regard to Municipal laws which are developed after translation.

In a monist country, a law emerges after the International law has been accepted and if it contradicts the International law, it automatically becomes null and void. International rule will continue to prevail.

In a dualist system, when the international law which is translated into a national law can be overridden by another national law on the principle of "lex posterior derogat legi priori", which means: the later law replaces the earlier one.

This means that a dualist state willingly or unwillingly can violate international law. A dualist system requires continuous screening of all subsequent national law for possible incompatibility with earlier international law.

Difference Monism theory and Dualist theory


  1. As per the advocates of natural law, Municipal law and International Law forms a single legal system.

  2. Monism is supported by the advocates of natural law.

  3. In Monism, there exists no need for translation of International into Municipal law in order to give it an effect.

  4. In a true monistic country if a national law contradicts International Law then it becomes null and void.

  5. If a monist state ratifies a treaty or a convention and does not create a law explicitly incorporating the treaty then their act of non-incorporation will not violate the International Law.

  6. In a monistic State International Law automatically gets embedded in the Municipal law and the contradicting part gets automatically translated away.

  7. Supporters of Monism: kelson

  8. State which follows a Monistic approach: Germany


  1. Municipal law and International Law are two different and distinct legal systems.

  2. It is supported by the advocates of positive law.

  3. In a dualist country, there exists a need for translation of International into Municipal law in order to give it an effect.

  4. In a true dualistic country, if a national law contradicts International law then it becomes doesn't become null and void, unless it is already translated in its municipal law

  5. If a dualist State ratifies a treaty or a convention but does not create a law explicitly incorporating the treaty, then their act of non-incorporation violates the International law.

  6. International law does not get automatically embedded in the Municipal law.

  7. Contradicting parts of the Municipal law has to be amended by the state, as it does not get automatically translated away in a dualist country.

  8. In the absence of a translation of International law into Municipal law, the International law will not exist as a law.

  9. Supporter: hersch lauterpatch, triepel.

  10. The country which follows: United Kingdom.


There are a few principal methods by which states implement treaties and some of them are; Adoption, Incorporation and Transformation.


As per the monist theory, if International law is adopted as Municipal law, then the treaty is automatically enforceable in Municipal law. However, some states need “translation” from the legislature for treaties to be enforceable and they are; France, Spain, Belgium Netherlands, USA. Other countries like Germany and Italy require an order of execution prior to the ratification (pre-legislative consent). It is usually called quasi-automatic incorporation, which authorizes the government to be committed towards the obligations of treaty and incorporating the treaty into the Municipal legal sphere.


This theory is usually practised by the dualist states. The theory of Incorporation involves enacting and implementing the legislation. International treaties have a higher status than that of the Municipal law (however not more than the Constitution).

The key difference between an incorporated treaty and an adopted treaty is the form it takes in Municipal law. Thus adoption is heavily reliant on the attitude of municipal courts. On the same line of argument, incorporation and transformation which leads to the enactment of the legislation, is not necessarily without any barriers, as it is on the discretion of the court whether to apply the principles of a treaty or not.

Judicial Discourse on Relationship Between International Law and Municipal Law:

State of West Bengal v Kesoram Industries Ltd. & others.

In this case, the Constitutional Bench of Supreme Court held that the Doctrine of Dualism is applicable in India and not the doctrine of Monism however if the municipal law isn’t limiting the extent of the statute, then, even if India is not a signatory to the treaty, the Supreme Court can Interpret the Statute.

Civil Rights Vigilance Committee S.L.R.C. College of Law Bangalore v. Union of India and others

The High Court of Karnataka while deciding this case, defined the relationship between International Law and the Municipal Law held that, as the increasing relevance of International law on the global and municipal scenario, several unique and novel queries are starting to be raised regarding the relationship between the two. However, the Hon’ble High Court held that Municipal Law & International Law are established on different sources can make different systems go simply incompatible.


Monism and dualism are usually conceived as two opposing theories of the International law and Municipal law relationship. Monism and dualism are regarded by many modern scholars as having limited explanatory power as theories as they fail to capture how International law works within States.

Notwithstanding anything, Monism and dualism hold power as analytical tools. They go about as predictable beginning stages for examinations of the connection among International and Municipal law. Various late choices in Municipal courts have seen a few researchers find Monism and dualism as potential approaches to comprehend Municipal legal thinking on International law.

19 views0 comments