Relationship Between International and Municipal Law: Horizontal approach

Relationship Between International and Municipal Law: Horizontal approach


 From how the name suggests, international law is applied at international level and looks after the relations of the states and to other subjects to international law and national. Whereas municipal law or state law is restricted into the boundaries of a state to individuals and corporate entities which are the bearers of right and duties thereunder. It is the reflection of state sovereignty and governs the relationship between the rights bearer. These two legal systems designed to operate in it’s own sphere distinctly.

The issue of how international law is implemented in the state becomes extremely important. The constitutional provisions of state for implementation of international law are also different. The international tribunals give effect to international law even if the international law is in conflict with municipal laws of parties to the case. The prima facie to the relationship would appear that these two are distinct parallels.

Oppenheim defines International law as

“Law of Nation or International Law is the name for the body of customary and conventional rules which are considered legally binding by civilized states in their relation with each other, within a community which by common consent of this community shall be enforced by external power.”

Municipal law governs the domestic aspect of the government and conflict between individuals and administrative apparatus. The interdependence and close knit character of the contemporary conflict in human rights, environmental, international investment make the relationship phenomenal with reference to paralleling role played by state within international law sphere.

The link between the two systems has gained prominence in modern international law, owing to the fact that a substantial portion of it is directly concerned with the acts of individuals who fall under the jurisdiction of municipal courts. As a result, a growing portion of international law is enforced in local courts to determine the link between two legal systems and the supremacy of two laws when they are in conflict.

The views of the jurist on the question of relationship of international law and municipal law are divergent which have led to the emergence of different theories.[1]

Brief About the Theories Governing their Relationship

It can be well quoted that

“Municipal law is a vertical law in which the parliament makes the regulations and citizens must follow them; on the other hand, international law is a horizontal law in which governments set the rules and are parties who must also follow them.”

Dualism Theory

International and municipal law, according to this theory, are two completely different legal systems. With regards to the theory international law has intrinsically different character from that of municipal law. The proponents of Dualist school believe that the disciplines are widely different and are not common in nature. 

 The two prominent positivists supported the theme of Dualism namely Triepel and Anzilotti.

According to Triepel,

““In municipal law, the subjects are persons, whereas in international law, the subjects are totally and exclusively the state.”

His definition went to the extent of saying that there was no possibility of any conflict between them. To criticise the theory given by Anzilotti lies in the fact that Pact sunt survenda does not represent the entire international law. Unfortunately, it was not accepted to the extent and jurists argued that the subject includes individuals, international organisations, non-state entities, belligerents. As far as judicial organs of international law and municipal law are concerned, state laws are the will of the states where as source of international law is the common will of states which is well known as ‘Gemeinwille’. It is pivotal to understand that states are strictly neither monist nor dualist per se. In most cases, for application of international law states require treaties to be signed between parties.



Monism theory

 It recognises one system where law is general as international law and municipal law are concomitant aspects of one system. Monism regards all law as single unity composed of binding legal rules irrespective of the fact weather those rules are obligatory in states, on individuals or on entities other than states in 18th century by two German scholars Moser and Martens. Kelsen, the name does not need any introduction because of his pure law theory in the positivism school of jurisprudence and given his monistic theory which is founded in a philosophic approach towards knowledge in general.

According to Kelsen,

“The unity or the science of law is necessary deduction from human cognition and its unity”

He was a strong believer to no distinction between the two legal spheres as both systems bound individuals although international law did so only mediately. In Monism there exists no requirement for interpretation of International into Municipal law to give it an impact. In a true monistic nation if state laws are contravened International Law, it becomes invalid and unjust.  In a monistic State International Law consequently gets embedded in the Municipal law and the repudiating part moves naturally deciphered away. Germany is the state who supported monism fully.[2]

 Application of International law into the arena of Municipal law: Horizontal Approach

  1. Specific Adaption/ specific incorporation/transformation theory

The positivists are of view that customary international law cannot directly and ‘ex proprio vigore’ be applied within the sphere of municipal law with regards to the rule of international law being a part of national law if specifically adopted. It’s based on dualist concept believe that it is followed by the municipal courts unless they undergo the transformation process and adopted by municipal courts and system.

2. Delegation Theory

The critics of transformation theory put forward a theory of delegation which revolves around the delegation of constitutional rules of international law to state constitution which is known as constitutional rules of international treaties. With regards to the theory the states are vested with the discretion to decide for themselves on enforcement of international provisions.

Horizontal Approach over other theories

Under article 38(1) of the Statute of the International Court of Justice (ICJ) which provides the role of treaties, customs and general principles in framing international legal system. The formation of International Laws is far more complicated than the creation of laws in national systems because international law systems are horizontal and decentralised.”

The distinction made between monism and dualism that follows a philosophical convention and neglects to hold fast to certain legal issues. The principle means to revoke such divisions and art a lawful request that limits the contention made by the past regulations. It aims eliminates the order among global law and metropolitan law and makes relationship among both these laws for a better legal interaction.


“The Doctrine of Harmonization, a version of the dualist perspective created, among others, by Fitzmaurice and Rousseau, aims to construct a recognised theoretical framework tied to reality.”

“When there is a conflict between states, the domestic will win out, leaving the state liable at the international level for any violations of its international law duties. “That states laws cannot derogate any international laws,” according to the case of “Martin v. Renold,” and “that in extreme cases where such legislation is passed that deviates or contradicts international law, that law would go through a judicial redrafting in order to harmonise with international law.”