
International law, also known as public international law and the law of nations, is the set of
rules
Rule or ruling may refer to:
Human activity
* The exercise of political or personal control by someone with authority or power
* Business rule, a rule pertaining to the structure or behavior internal to a business
* School rule, a rule tha ...
, norms,
legal customs and standards that
states
State most commonly refers to:
* State (polity), a centralized political organization that regulates law and society within a territory
**Sovereign state, a sovereign polity in international law, commonly referred to as a country
**Nation state, a ...
and other actors feel an obligation to, and generally do, obey in their mutual relations. In international relations, actors are simply the individuals and collective entities, such as states,
international organizations
An international organization, also known as an intergovernmental organization or an international institution, is an organization that is established by a treaty or other type of instrument governed by international law and possesses its own leg ...
, and non-state groups, which can make behavioral choices, whether lawful or unlawful. Rules are formal, typically written expectations that outline required behavior, while norms are informal, often unwritten guidelines about appropriate behavior that are shaped by custom and social practice. It establishes norms for states across a broad range of domains, including
war and
diplomacy
Diplomacy is the communication by representatives of State (polity), state, International organization, intergovernmental, or Non-governmental organization, non-governmental institutions intended to influence events in the international syste ...
,
economic relations, and
human rights
Human rights are universally recognized Morality, moral principles or Social norm, norms that establish standards of human behavior and are often protected by both Municipal law, national and international laws. These rights are considered ...
.
International law differs from state-based
domestic legal systems in that it operates largely through
consent
Consent occurs when one person voluntarily agrees to the proposal or desires of another. It is a term of common speech, with specific definitions used in such fields as the law, medicine, research, and sexual consent. Consent as understood i ...
, since there is no universally accepted authority to enforce it upon
sovereign state
A sovereign state is a State (polity), state that has the highest authority over a territory. It is commonly understood that Sovereignty#Sovereignty and independence, a sovereign state is independent. When referring to a specific polity, the ter ...
s. States and non-state actors may choose to not abide by international law, and even to breach a
treaty
A treaty is a formal, legally binding written agreement between sovereign states and/or international organizations that is governed by international law. A treaty may also be known as an international agreement, protocol, covenant, convention ...
, but such violations, particularly of
peremptory norm
A peremptory norm (also called ) is a fundamental principle of international law that is accepted by the international community of states as a norm from which no derogation is permitted.
There is no universal agreement regarding precisely w ...
s, can be met with disapproval by others and in some cases coercive action including diplomacy,
economic sanctions
Economic sanctions or embargoes are Commerce, commercial and Finance, financial penalties applied by states or institutions against states, groups, or individuals. Economic sanctions are a form of Coercion (international relations), coercion tha ...
, and war. The lack of a final authority in international law can also cause far reaching differences. This is partly the effect of states being able to interpret international law in a manner which they seem fit. This can lead to problematic stances which can have large local effects.
The
sources of international law
International law, also known as "law of nations", refers to the body of rules which regulate the conduct of sovereign states in their relations with one another. Sources of international law include treaties, international customs, general wi ...
include
international custom (general state practice accepted as law), treaties, and general principles of law recognised by most national legal systems. Although international law may also be reflected in
international comity—the practices adopted by states to maintain good relations and mutual recognition—such traditions are not
legally binding. Since good relations are more important to maintain with more powerful states they can influence others more in the matter of what is legal and what not. This is because they can impose heavier consequences on other states which gives them a final say. The
relationship and interaction between a
national legal system and international law is complex and variable. National law may become international law when treaties permit national jurisdiction to
supranational tribunals such as the
European Court of Human Rights
The European Court of Human Rights (ECtHR), also known as the Strasbourg Court, is an international court of the Council of Europe which interprets the European Convention on Human Rights (ECHR). The court hears applications alleging that a co ...
or the
International Criminal Court
The International Criminal Court (ICC) is an intergovernmental organization and International court, international tribunal seated in The Hague, Netherlands. It is the first and only permanent international court with jurisdiction to prosecute ...
. Treaties such as the
Geneva Conventions
upright=1.15, The original document in single pages, 1864
The Geneva Conventions are international humanitarian laws consisting of four treaties and three additional protocols that establish international legal standards for humanitarian t ...
require national law to conform to treaty provisions. National laws or
constitutions may also provide for the implementation or integration of international legal obligations into domestic law.
Terminology
The modern term "international law" was originally coined by
in his 1789 book ''
Introduction to the Principles of Morals and Legislation'' to replace the older law of nations, a direct translation of the late medieval concepts of ''
ius gentium'', used by
Hugo Grotius
Hugo Grotius ( ; 10 April 1583 – 28 August 1645), also known as Hugo de Groot () or Huig de Groot (), was a Dutch humanist, diplomat, lawyer, theologian, jurist, statesman, poet and playwright. A teenage prodigy, he was born in Delft an ...
, and ''droits des gens'', used by
Emer de Vattel
Emmerich de Vattel ( 25 April 171428 December 1767) was a philosopher, diplomat, and jurist.
Vattel's work profoundly influenced the development of international law. He is most famous for his 1758 work ''The Law of Nations''. This work was his ...
. The definition of international law has been debated; Bentham referred specifically to relationships between states which has been criticised for its narrow scope.
Lassa Oppenheim
Lassa Francis Lawrence Oppenheim (30 March 1858 – 7 October 1919) was a German jurist. He has been characterized as the father of the modern discipline of international law, especially the hard legal positivist school of thought. His two-volum ...
defined it in his treatise as "a law between sovereign and equal states based on the common consent of these states" and this definition has been largely adopted by international legal scholars.
There is a distinction between public and
private international law
Conflict of laws (also called private international law) is the set of rules or laws a jurisdiction applies to a case, transaction, or other occurrence that has connections to more than one jurisdiction."Conflict of Laws", ''Black's Law Dictio ...
; the latter is concerned with whether national courts can claim
jurisdiction
Jurisdiction (from Latin 'law' and 'speech' or 'declaration') is the legal term for the legal authority granted to a legal entity to enact justice. In federations like the United States, the concept of jurisdiction applies at multiple level ...
over cases with a foreign element and the application of foreign judgments in domestic law, whereas public international law covers rules with an international origin. The difference between the two areas of law has been debated as scholars disagree about the nature of their relationship.
Joseph Story
Joseph Story (September18, 1779September10, 1845) was an American lawyer, jurist, and politician who served as an associate justice of the Supreme Court of the United States from 1812 to 1845. He is most remembered for his opinions in ''Martin ...
, who originated the term "private international law", emphasised that it must be governed by the principles of public international law but other academics view them as separate bodies of law. Another term, transnational law, is sometimes used to refer to a body of both national and international rules that transcend the nation state, although some academics emphasise that it is distinct from either type of law. It was defined by
Philip Jessup as "all law which regulates actions or events that transcend national frontiers".
A more recent concept is
supranational law, which was described in a 1969 paper as "
relatively new word in the vocabulary of politics". Systems of supranational law arise when nations explicitly cede their right to make decisions to this system's judiciary and legislature, which then have the right to make laws that are directly effective in each member state. This has been described as "a level of international integration beyond mere intergovernmentalism yet still short of a federal system". The most common example of a
supranational system is the
European Union
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
.
History

With origins tracing back to
antiquity, states have a long history of negotiating interstate agreements. An initial framework was conceptualised by the Ancient Romans and this idea of ''
ius gentium'' has been used by various academics to establish the modern concept of international law. Among the earliest recorded examples are
peace treaties between the
Mesopotamia
Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system, in the northern part of the Fertile Crescent. Today, Mesopotamia is known as present-day Iraq and forms the eastern geographic boundary of ...
n city-states of
Lagash
Lagash (; cuneiform: LAGAŠKI; Sumerian language, Sumerian: ''Lagaš'') was an ancient city-state located northwest of the junction of the Euphrates and Tigris rivers and east of Uruk, about east of the modern town of Al-Shatrah, Iraq. Lagash ( ...
and
Umma
Umma () in modern Dhi Qar Province in Iraq, was an ancient city in Sumer. There is some scholarly debate about the Sumerian and Akkadian names for this site. Traditionally, Umma was identified with Tell Jokha. More recently it has been sugges ...
(approximately 3100 BCE), and
an agreement between the
Egyptian pharaoh,
Ramesses II
Ramesses II (sometimes written Ramses or Rameses) (; , , ; ), commonly known as Ramesses the Great, was an Pharaoh, Egyptian pharaoh. He was the third ruler of the Nineteenth Dynasty of Egypt, Nineteenth Dynasty. Along with Thutmose III of th ...
, and the
Hittite king
The dating and sequence of Hittite kings is compiled by scholars from fragmentary records, supplemented by the finds in Ḫattuša and other administrative centers of cuneiform tablets and more than 3,500 seal impressions providing the names, tit ...
,
Ḫattušili III
Hattusili III (Hittite language, Hittite: "from Hattusa") was king of the Hittite empire (New Kingdom) –1245 BC (middle chronology) or 1267–1237 BC (short chronology timeline)., pp.xiii-xiv
Early life and family
Much of what is known about ...
, concluded in 1279 BCE. Interstate pacts and agreements were negotiated and agreed upon by
polities
A polity is a group of people with a collective identity, who are organized by some form of political institutionalized social relations, and have a capacity to mobilize resources.
A polity can be any group of people organized for governance ...
across the world, from the eastern
Mediterranean
The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...
to
East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
. In
Ancient Greece
Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically r ...
, many
early peace treaties were negotiated between its
city-states and, occasionally, with neighbouring states. The
Roman Empire
The Roman Empire ruled the Mediterranean and much of Europe, Western Asia and North Africa. The Roman people, Romans conquered most of this during the Roman Republic, Republic, and it was ruled by emperors following Octavian's assumption of ...
established an early conceptual framework for international law, ''jus gentium'', which governed the status of foreigners living in Rome and relations between foreigners and
Roman citizens. Adopting the Greek concept of
natural law
Natural law (, ) is a Philosophy, philosophical and legal theory that posits the existence of a set of inherent laws derived from nature and universal moral principles, which are discoverable through reason. In ethics, natural law theory asserts ...
, the Romans conceived of ''jus gentium'' as being universal. However, in contrast to modern international law, the Roman law of nations applied to relations with and between foreign individuals rather than among political units such as states.
Beginning with the
Spring and Autumn period
The Spring and Autumn period () was a period in History of China, Chinese history corresponding roughly to the first half of the Eastern Zhou (256 BCE), characterized by the gradual erosion of royal power as local lords nominally subject t ...
of the eighth century BCE, China was divided into numerous states that were often at war with each other. Rules for diplomacy and treaty-making emerged, including notions regarding
just grounds for war, the rights of neutral parties, and the consolidation and partition of states; these concepts were sometimes applied to relations with
barbarian
A barbarian is a person or tribe of people that is perceived to be primitive, savage and warlike. Many cultures have referred to other cultures as barbarians, sometimes out of misunderstanding and sometimes out of prejudice.
A "barbarian" may ...
s along China's western periphery beyond the
Central Plains. The subsequent
Warring States period
The Warring States period in history of China, Chinese history (221 BC) comprises the final two and a half centuries of the Zhou dynasty (256 BC), which were characterized by frequent warfare, bureaucratic and military reforms, and ...
saw the development of two major schools of thought,
Confucianism
Confucianism, also known as Ruism or Ru classicism, is a system of thought and behavior originating in ancient China, and is variously described as a tradition, philosophy, Religious Confucianism, religion, theory of government, or way of li ...
and
Legalism, both of which held that the domestic and international legal spheres were closely interlinked, and sought to establish competing normative principles to guide foreign relations. Similarly, the
Indian subcontinent
The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian Ocean between the Bay of Bengal to the east and the Arabian Sea to the west. It is now divided between Bangladesh, India, and Pakista ...
was divided into various states, which over time developed rules of neutrality,
treaty law, and international conduct, and established both temporary and permanent
embassies.
Following the
collapse of the western Roman Empire in the fifth century CE, Europe fragmented into numerous often-warring states for much of the next five centuries. Political power was dispersed across a range of entities, including the
Church,
mercantile city-states, and kingdoms, most of which had overlapping and ever-changing jurisdictions. As in China and India, these divisions prompted the development of rules aimed at providing stable and predictable relations. Early examples include
canon law
Canon law (from , , a 'straight measuring rod, ruler') is a set of ordinances and regulations made by ecclesiastical jurisdiction, ecclesiastical authority (church leadership) for the government of a Christian organization or church and its membe ...
, which governed