INTERNATIONAL LAW
ANDERS HENRIKSEN
CHAPTER 1
1.1 INTRODUCTION
Public international law deals with legal issues of concern to more than one state. International law is
traditionally defined as the system of law that regulates the interrelationship of sovereign states and their rights
and duties to one another, but that must be added a host of other actors, most notably international organizations
and individuals who also possess rights and/or obligations under international law.
International law is a decentralized legal system where it is primarily up to the legal subjects themselves to
create, interpret and enforce the law.
International law is a reflection of the society to which it applies changes over time.
1.2 A BRIEF HISTORY OF INTERNATIONAL LAW
1.2.1 EARLY MODERN INTERNATIONAL LAW
Roman Empire
Natural law (=jus naturale) contained an all-embracing set of ideas about natural and social life in the universe
and, though primarily focused on the individual and his or her relations to the world, it also applied to states by
virtue of the fact that riles were also indivi duals and therefor subject to it.
Law of people/ nations (=jus gentium) were a set of rules grounded in natural reason, which was believed to be
common to all peoples.
While an elaborate international legal structure did not yet exist, legal obligation and contracts were
nevertheless created in day-to-day relations of the communication at the time, leading to numerous agreements
on issues such as the treatment of merchants, maritime traders and diplomatic envoys and the conduct of war and
the exchange and ransoming of prisoners of war.
Middle Ages
The international society of this period consisted of overlapping normative systems and divers communities.
The Holy Roman Empire and the Catholic Church formed a transnational network of entities. Additionally, new
legal frameworks emerged, such as lex mercatoria (the Law Marchant), which governed trade and maritime
customs.
Colonial Era
Western European powers expanded their dominance by subjugating indigenous Indian populations, marking
the rise of colonialism.
17th/18th Century
Modern international law began to take shape, especially in the wake of the 1648 Peace of Westphalia. This
event solidified the concept of nation-states, established state sovereignty, and emphasizes the principle of
equality among states.
,1.2.2 PEACE OF WESTPHALIA
The Peace of Westphalia in 1648 was the ‘birth’ of the international state system, it brought an end to the
Thirty Years War that had ravaged continental Europe. In the peace treaties of Westphalia, consisting of the
Peace of Munster and the Treaties of Munster and Osnabruck, the major European powers sought to establish a
semblance (=schijn) of order and structure in an otherwise anarchial and disorderly European world. The idea
was to reduce the powers of transnational forces, like empire and religion, and instead compartmentalize
territory and individuals into sovereign states.
By seeking to create an international order from a multiplicity of ‘states’ of equal legal importance,
Westphalia was a turning point, and what had initially merely been conceived of as a concept of order for war-
torn Europe spread to the rest of the world.
1.2.3 THE 19 T H CENTURY AND THE ERA OF POSITIVISM
During the 19th century, positivist turns are entering international law. Positivism, in the context of law, is the
philosophy that legal systems derive their authority not from moral or natural principles but from the explicit
will and consent of states. This means that laws are seen as binding because states agree to them, rather than
because they are "just" or "right."
This positivist perspective became prominent as states increasingly emphasized their sovereignty and
autonomy. In this framework, international law relied on treaties, agreements, and customary practices explicitly
consented to by states, making state will the primary source of legal obligations.
International law also underwent radical shifts in this era. Devastating colonial practices, such as the partition of
Africa during the Berlin Conference, starkly highlighted the dominance of state power under positivist
principles, often with disregard for moral or ethical considerations.
1.2.4 THE INTERWAR PERIOD
In 1919, the League of Nations marked a turning point by striving to establish peaceful dispute resolution
mechanisms, including the creation of the Permanent Court of International Justice (PCIJ), later replaced by
the International Court of Justice.
1.2.5 THE PERIOD AFTER THE SECOND WORLD WAR
However, after its limitations became evident, the League of Nations was replaced by the United Nations.
With the introduction of the UN Charter, groundbreaking principles were codified, such as the outright ban on
the use of force, self-determination of peoples, state equality, and collective security through the United Nations
Security Council (UNSC). These developments further reflected a balance between positivist legal structures
and emerging principles of justice.
The United Nations General Assembly (UNGA), were all the member states where represented, also played a
critical role by initiating decolonization, emphasizing the growing recognition of rights and moral imperatives.
Meanwhile, regional organizations, such as the European Union and the NATO, showcased advanced models
of cooperation.
While positivism originally emphasized horizontal relationships between states (focused on coexistence),
modern international law has increasingly addressed vertical and transnational issues, moving toward
cooperation and collective progress.
, 1.3 THE STRUCTURES OF INTERNATIONAL LAW
1.3.1 INTRODUCTION – A SOCIETY OF SOVEREIGN NATION STATES
Only when an issue is of interest to more than one national sovereign will international law enter the picture. The
scope of international law is thereby determined by the inadequacy of national law.
Two ways in which an issue becomes of interest of more than one state define the two substantive structures of
international law:
1. Two or more states have colliding interest in the substance of the issue the international law of
coexistence.
2. The involved states have agreed in a treaty to turn the issue into one of international character the
international law of cooperation.
1.3.2 THE INTERNATIONAL LAW OF COEXISTENCE
The international law of coexistence (=general international law) contains the legal answers to questions that are
inherently of interest to more than one state and required to separate the powers of the sovereign states and
thereby uphold peaceful coexistence.
Legal structure mostly horizontal how sovereign states interact with – and between – eachother.
ANDERS HENRIKSEN
CHAPTER 1
1.1 INTRODUCTION
Public international law deals with legal issues of concern to more than one state. International law is
traditionally defined as the system of law that regulates the interrelationship of sovereign states and their rights
and duties to one another, but that must be added a host of other actors, most notably international organizations
and individuals who also possess rights and/or obligations under international law.
International law is a decentralized legal system where it is primarily up to the legal subjects themselves to
create, interpret and enforce the law.
International law is a reflection of the society to which it applies changes over time.
1.2 A BRIEF HISTORY OF INTERNATIONAL LAW
1.2.1 EARLY MODERN INTERNATIONAL LAW
Roman Empire
Natural law (=jus naturale) contained an all-embracing set of ideas about natural and social life in the universe
and, though primarily focused on the individual and his or her relations to the world, it also applied to states by
virtue of the fact that riles were also indivi duals and therefor subject to it.
Law of people/ nations (=jus gentium) were a set of rules grounded in natural reason, which was believed to be
common to all peoples.
While an elaborate international legal structure did not yet exist, legal obligation and contracts were
nevertheless created in day-to-day relations of the communication at the time, leading to numerous agreements
on issues such as the treatment of merchants, maritime traders and diplomatic envoys and the conduct of war and
the exchange and ransoming of prisoners of war.
Middle Ages
The international society of this period consisted of overlapping normative systems and divers communities.
The Holy Roman Empire and the Catholic Church formed a transnational network of entities. Additionally, new
legal frameworks emerged, such as lex mercatoria (the Law Marchant), which governed trade and maritime
customs.
Colonial Era
Western European powers expanded their dominance by subjugating indigenous Indian populations, marking
the rise of colonialism.
17th/18th Century
Modern international law began to take shape, especially in the wake of the 1648 Peace of Westphalia. This
event solidified the concept of nation-states, established state sovereignty, and emphasizes the principle of
equality among states.
,1.2.2 PEACE OF WESTPHALIA
The Peace of Westphalia in 1648 was the ‘birth’ of the international state system, it brought an end to the
Thirty Years War that had ravaged continental Europe. In the peace treaties of Westphalia, consisting of the
Peace of Munster and the Treaties of Munster and Osnabruck, the major European powers sought to establish a
semblance (=schijn) of order and structure in an otherwise anarchial and disorderly European world. The idea
was to reduce the powers of transnational forces, like empire and religion, and instead compartmentalize
territory and individuals into sovereign states.
By seeking to create an international order from a multiplicity of ‘states’ of equal legal importance,
Westphalia was a turning point, and what had initially merely been conceived of as a concept of order for war-
torn Europe spread to the rest of the world.
1.2.3 THE 19 T H CENTURY AND THE ERA OF POSITIVISM
During the 19th century, positivist turns are entering international law. Positivism, in the context of law, is the
philosophy that legal systems derive their authority not from moral or natural principles but from the explicit
will and consent of states. This means that laws are seen as binding because states agree to them, rather than
because they are "just" or "right."
This positivist perspective became prominent as states increasingly emphasized their sovereignty and
autonomy. In this framework, international law relied on treaties, agreements, and customary practices explicitly
consented to by states, making state will the primary source of legal obligations.
International law also underwent radical shifts in this era. Devastating colonial practices, such as the partition of
Africa during the Berlin Conference, starkly highlighted the dominance of state power under positivist
principles, often with disregard for moral or ethical considerations.
1.2.4 THE INTERWAR PERIOD
In 1919, the League of Nations marked a turning point by striving to establish peaceful dispute resolution
mechanisms, including the creation of the Permanent Court of International Justice (PCIJ), later replaced by
the International Court of Justice.
1.2.5 THE PERIOD AFTER THE SECOND WORLD WAR
However, after its limitations became evident, the League of Nations was replaced by the United Nations.
With the introduction of the UN Charter, groundbreaking principles were codified, such as the outright ban on
the use of force, self-determination of peoples, state equality, and collective security through the United Nations
Security Council (UNSC). These developments further reflected a balance between positivist legal structures
and emerging principles of justice.
The United Nations General Assembly (UNGA), were all the member states where represented, also played a
critical role by initiating decolonization, emphasizing the growing recognition of rights and moral imperatives.
Meanwhile, regional organizations, such as the European Union and the NATO, showcased advanced models
of cooperation.
While positivism originally emphasized horizontal relationships between states (focused on coexistence),
modern international law has increasingly addressed vertical and transnational issues, moving toward
cooperation and collective progress.
, 1.3 THE STRUCTURES OF INTERNATIONAL LAW
1.3.1 INTRODUCTION – A SOCIETY OF SOVEREIGN NATION STATES
Only when an issue is of interest to more than one national sovereign will international law enter the picture. The
scope of international law is thereby determined by the inadequacy of national law.
Two ways in which an issue becomes of interest of more than one state define the two substantive structures of
international law:
1. Two or more states have colliding interest in the substance of the issue the international law of
coexistence.
2. The involved states have agreed in a treaty to turn the issue into one of international character the
international law of cooperation.
1.3.2 THE INTERNATIONAL LAW OF COEXISTENCE
The international law of coexistence (=general international law) contains the legal answers to questions that are
inherently of interest to more than one state and required to separate the powers of the sovereign states and
thereby uphold peaceful coexistence.
Legal structure mostly horizontal how sovereign states interact with – and between – eachother.
