University of Cambridge

International Law And Municipal Law: The Interface


It is the nature of man to live in communities.  He lives in this fashion in every part of the world today, and the evidence of history and pre-history shows how long he has been doing so.  But then it must be noted that where people live together conflict is bound to arise due to various conflicting interests among the people.  Also, bearing in mind that everybody tries to work hard, obtains basic needs and all other things which help to make life happy and comfortable which are incidentally in short supply, since the supply is always in short in proportion to the demand, competition for them sets in.  It is a race in which we all engage, and in every race or game there must be rules and regulations. Else, we are moving towards the ‘state of nature’ as enunciated by Hobbes.  Therefore, the existence of rules and regulations (law) becomes a sine qua non to the peaceful co-existence of people and nations all over the world.

This chapter therefore, attempts a critical examination of International and Municipal laws.  The chapter is divided into three parts.  Part one which is the introduction provides theoretical background for the work.  In it, clarifications of some concepts that are germane to the study are done.  It also looks briefly at purposes and characteristics of law.   Part two compares vividly international law and municipal law looking at the debate on the relationship between the two using the contending theories.  Part three, which is the concluding aspect, presents a complementary nature of international law and municipal law, thereby viewing both laws as real, irrespective of their peculiarities.

Understanding the Concepts

Since conceptual clarification is a form of intellectual ritual that gives clarity and validity to any discussion, it is therefore necessary to explain concepts that are germane to this study for the purpose of deeper understanding.

The Concept of Law

There have been various definitions of law by different scholars across the global intellectual communities.  These definitions exist, ranging from the philosophical to the practical, Plato called law social control; William Blackstone (1977) sees law as rule, specifying what was right and what was wrong.  For the purpose of this study, law is viewed as a body of rules that establish a certain level of social conduct, or duties that members of the society honour (Davidson, 1998:3).

Law simply means an arrangement that coordinates and confines people’s behaviours to conform to an agreed general ways of human conduct in a given society, with a threat of sanctions against defiant behaviours. Inferred from the above definitions is the need to obey the law. This is because disobedience may attract sanctions that may result in imprisonment, fine or death, depending on the nature of offence. Law may also be defined as a body of rules or regulations governing the conduct of human beings in their social regulations.

The Concept of Municipal Law

Municipal law is the internal law of the state, binding on the citizens of the state.  It is defined as the domestic law of a state regulating the conduct of individuals and legal entities within it (Aguda, 1999).  It is national or internal law of a state.  Shaw sees municipal law as law that governs the domestic aspects of government and deals with issues between individuals and the administrative apparatus (Shaw, 1997:105).

The Concept of International Law

It is an indisputable fact that international law is a victim of definitional pluralism; this is because many scholarly definitions have been given to it by various scholars of repute from different perspectives.  Some of these definitions will be explored for the purpose of this study.

Khan et al (1968) defines it as a ‘body of rules, laws, and norms, which serves to limit the sovereignty of state in the international society.  Oppenheim (1995) sees it as the ‘body of customary and treaty rules which are considered legally binding by states, in their intercourse with each other.’  Jessup (1968) presents it as the body of laws, which is applicable to states in their relations and to individuals in their relations to other states.  In the same vein,  Kolawole (1997, 278) defines international law or what he calls the ‘law of nations’ as the body of rules and principles of action which are binding upon civilised states in their relations with one another.  International law is the law at the international level made by the collective will of states and to lesser degree organisation and individuals (Shaw, 1997, 105).  In essence, international law is a body of generally accepted principles and rules regulating or controlling the conduct of states, individuals and international organisations for the purpose of peaceful coexistence in the international plane.

Dimensions of International Law

            The scope of international law can be categorised into six broad items, namely: one, the law of peace, which seeks the peaceful settlement of international disputes.  Two, the law of war, since conflict is an inevitable outcome of human and states relations, conducts of hostilities, must conform with laid-down regulations in terms of types of military wares and ammunition to be used, and stages of their utilisation, targets and non targets of attack, areas of combat, treatment of civilians, journalists and prisoners of war and refuges; and the duties of humanitarian agencies such as the Red-Cross otherwise called ‘doctor without borders’. Three, the law of neutrality, international law forbids aggression on neutral states in war.  It also spells out reciprocal responsibilities for neutral states.  Law forbids them to render any form of assistance whatever military or civil to any of the parties engaged in hostility.  Four, mercantile laws, which relate to regulations on international trade, foreign investment and multi-lateral trade agreements by states. 

Five, is the law of the sea.  The sea is very vital to the world economy as it provides varied marine food and mineral resources. It serves as a means of international transportation, and it serves as strategic resource for national defence.  For these reasons, nations have fought wars over marine resources.  Consequently, activities of states in the sea need to be regulated in order to present inter-state disputes.  Six, convention on the use of outer spaces.  The law regulates the exploration and launching of objects into outer space (Ajayi, 2000).

Characteristics and Purposes of Law

The inherent nature of human beings is their unpredictability in terms of behavioural conduct. States, groups and international organisations, like individuals who constitute membership of these social formations, suffer from this innate problem.  Therefore, for law to really serve its purposes, a competent and constituted body that has recognised authority must make such law.  It must also be ultimately enforceable; any law that cannot be enforced is no law.  It must also be dynamic because society in which it operates is dynamic.  Law should also be consensual.  International law is one of consensus rather than one of force.  Even in the national society laws are only laws when one consents to it.  It might be out of fear of reprisal or coercion.

Law generally serves the following purposes in any society.  Law regulates conduct, maintains peace, and provides protection and means of achieving justice.

Specifically, law serves as a tool of order; as a tool order, it promotes order within the national and international society.  There is no denying the fact that a comprehensive set of rules, regulations, obligations, rights, legal doctrines and decisions of national and international tribunals on legal matters does help to promote international order.  Law regulates the behaviour of the citizenry.  Without law, society would have been disorganised and become ungovernable (Kolawole, 1997).

A scholar have identified the functions of international law, which include minimising frictions between and among states, stabilising the behaviour of states, facilitating cooperation between and among states, protecting individuals, settling disputes and serving as a tool of public relations and propaganda (Adeniran, 1983).

International law also serves as an instrument of national policy.  It contributes to a nation’s means of attaining its objectives in foreign policy.  It also serves as integrative force, in the world community, since no state can live in isolation, it atomised the entire states and people of the world into one whole as they are all subjects of the law without prejudice to race, colour or class (Ajayi, 2000).

Comparing International Law and Municipal Law

The relationship between international law and municipal law is full of theoretical problems.  The international legal literature on the subject records two main principal theories involved in the debate.  But it is to be noted that this part does not necessarily distinguish or differentiate international law from municipal law or give one primacy over the other, but rather, justifies the existence of both laws as laws in the real sense of it.  Although, some of the arguments put forward by different schools of thought to explain the relationship between the two laws will be explored for theoretical explanation and academic consumption.

The dualist or pluralist school of thought assumes that international law and municipal law are two separate legal systems, which exist independently of each other (Malanczuk, 1997, 63-71).  Dualism stresses that the rules of the systems of international and municipal laws exist separately and cannot purport to have effect on, or overrule the other.  This according to the school is because of the fundamentally different legal structure employed on one hand by the state, and on the other hand as between states (Malanczuk, 1997).

The dualist position is accepted by the posivists like Triepel and Anzillot.  Triepel maintains that international law must be incorporated into the municipal law, because the subject of state is the individual whereas the subject of international law is abstract entity known as the state.  Since subjects are not the same, there has to be a transformation from one to the other, i.e. international law has to be transformed into the state law before it can be applied to individuals.  This process is also called ‘Transformation theory’.  The claim of Triepel as regards state as only subject of international law can no longer be sacrosanct due to dynamism in law.  In the contemporary international law, individuals are seen as subject but with limited capacity. 

The 1945 Nuremberg Trial made individuals subject of international law; there was also Angola Trial, etc.  Anzilloti (1967) talks of the conditioning of the two laws.  In his opinionated view, state laws are imperatival and hence it has to be obeyed, whereas international law is in the nature of promises; it is therefore necessary to transform a promise into command before it becomes applicable in the municipal law.  The position also is not sacrosanct, in the sense that law is not necessarily command, people obey the law when they consent to it and often times people obey because of the possible gains that can be acquired.

The second school of thought known as Monist, has a unitary perception of the law and understands both international law and municipal law as forming part of one and the same legal order.  The most radical version of the Monist approach was formulated by Kelsen, in his view, ‘the ultimate source of validity of all law’, is derived from a basic rule of international law. 

Kelsen theory implies that all rules of international law were supreme over municipal law, that a municipal law inconsistent with international law was automatically null and void and that rules of international law were directly applicable in the domestic spheres of state.  Kelsen’s view was on formalistic logical grounds.  They opposed strict division of the two laws as demonstrated by the dualists and accept the unitary view of law as a whole.  Kelsen utilises the philosophy of Kant as its basis.

Law is regarded as constituting an order which lays down patterns of behaviour that ought to be followed, coupled with the provision for sanctions, which are employed once an illegal act or course of conduct has occurred or been embarked upon.  Since the same definition implies both within internal sphere and international sphere, a logical unity is forged. Since states own their legal relationship to the roles of international law, and since states cannot be equal before the law without a rule to that effect, it follows that international law is superior to or more basic than municipal law. 

Kelsen emphasises the unity of the entire legal order upon the basis of the predominance of international law by declaring that it is the basic norm of the international legal order, which is the ultimate reason of validity of the national legal orders too (Kelsen, 1997).

Lauterpacht in his contribution uphold a strong ethical position with deep concern for human right.  He sees the primary function of law as concerned with the well-being of individuals and advocates the supremacy of international law as the best method of attaining this.

Interestingly, Article 27 of the Vienna Convention on the law of treaties states that: a party may not invoke the provisions of its internal laws as justification for its failure to carry out an international agreement.  However, expression on the supremacy on the international law over municipal law in international tribunals does not mean that the provisions of domestic legislation are either irrelevant or necessary.  On the contrary, the role of international legal rules is vital to the working of the international legal machine.

One of the ways that is possible to understand and discover a state’s legal position on a variety of topic important to international law is by examining the municipal laws.  A country will express its opinion on such vital international matter at the extent of its territorial sea or the justification it claims or the conditions for the acquisition of nationality through the medium of its domestic law making.  Thus, it is quite often that in the course of deciding a case before it, an international court will feel the necessity to make a study of relevant pieces of municipal legislation.  The rules of municipal law can be utilised as evidences of compliance or non-compliance with international obligations (Shaw, 1997).

Complementary Nature of International Law and Municipal Law

International law does not entirely ignore municipal law.  For example, municipal law may be used as evidence of international custom or of general principles of law, which are both sources of international law.  Moreover, international law leaves certain questions to be decided by the municipal law (Akhurst, 1977).

Harmonisation theory succinctly provides an answer to the true relationship of the two laws by asserting that:

The starting point in the legal order is that man lives not in one jurisdiction, but in both.  International law and municipal law are concordant bodies of doctrine, autonomous but harmonious in their aim of basic human good.  When faced with an actual problem, a municipal court applies the rules operative within its jurisdiction and may in fact, apply international law to the exclusion of municipal law, or vice-versa (Aguda, 1993: 32).

A treaty or other rule of international law imposes an obligation on states to enact a particular rule as part of their own municipal law.  Similarly, there is a general duty for states to bring domestic law into conformity with obligation under international law either through transformation, incorporation, adoption or reception, e.g. treaties ratified in accordance with the constitution automatically become part of the municipal law of the USA.  In Britain, the traditional rule is that customary international law automatically forms part of English law (Akhurst, 1977).

In a case before a municipal court, a rule of international law may be brought forward as a defence to a charge.  For example, a vessel may be prosecuted for being in what the domestic terms is regarded as territorial waters, but in international law, it would be treated as part of the high seas.

Okeke (1986:6) puts it in this manner:

…as states grow in their international outlook, and as they participate in either the creation of new rules of international law or in the re-definition of the already existing ones, it must be borne in mind that the world is now advancing on the principle of interdependence and mutual cooperation.  The age of holding tenaciously to the principle of absolute sovereignty is far gone.  Indeed, a state by taking laws to be in conformity with international law is a legitimate exercise of the sovereignty of such a state.

Okeke’s position stresses the dynamism in law and the society, when the law operates and the need for global intercourse of nation for global benefits; and such interaction must be regulated with law both at national and international levels so as to have peaceful and ordered world.

Okeke in his analysis cited a section each from the constitution of Germany and the United States of America to affirm the interconnectedness of international and municipal laws. The constitution of the Federal Republic of Germany provides:


            The general rules of public international law are an integral

             part of the federal law. They shall take precedence over the

            laws and shall directly create rights and duties for the inhabitants

             of the federal territory (Okeke, 1986).

In the same manner, the American constitution also provides:

            The constitution and the laws of the United States, which shall

             be made in pursuance thereof, and all treaties made, or which

             shall be the supreme law of the land, and the judges in every state

             shall be bound thereby, and everything in the constitution or laws

             of any state to the contrary notwithstanding.

In addition, the rule of the municipal law can be utilised as evidences of compliance or non-compliance with international obligations, e.g. the issue of respect of fundamental human rights.  Though, in some countries the law will sometimes fail to reflect the correct rule of international law, but this does not necessarily mean that states will be breaking international law.


From the submissions above, ranging from definitions of law, characteristics and purposes to relationship and complimentary nature of municipal law and international law, it is clear that both laws possess the qualities of law and all that takes to be called laws.  They serve the same purposes and perform functions of law because they are meant to regulate conduct, maintain peace, provide protection, achieve justice, etc.  They are both enforceable; they have different mechanisms of enforcement and agencies.  They are both dynamic in nature, they are made by competent and recognised authority, etc.  As a matter of fact, both laws have been able to work towards achieving well ordered societies, which is the ultimate goal of any law.  Therefore, international law and municipal laws are real laws.


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