The '' ius gentium'' or ''jus gentium'' (

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

for "law of nations") is a concept of

international law International law (also known as public international law and the law of nations) is the set of rules, norms, and standards generally recognized as binding between states. It establishes normative guidelines and a common conceptual framework for ...

within the ancient Roman legal system and Western law traditions based on or influenced by it. The ''ius gentium'' is not a body of statute law nor a

legal code A code of law, also called a law code or legal code, is a systematic collection of statutes. It is a type of legislation that purports to exhaustively cover a complete system of laws or a particular area of law as it existed at the time the cod ...

, but rather

customary law A legal custom is the established pattern of behavior that can be objectively verified within a particular social setting. A claim can be carried out in defense of "what has always been done and accepted by law". Customary law (also, consuetudina ...

thought to be held in common by all ''gentes'' ("peoples" or "nations") in "reasoned compliance with standards of international conduct". Following the

Christianization Christianization ( or Christianisation) is to make Christian; to imbue with Christian principles; to become Christian. It can apply to the conversion of an individual, a practice, a place or a whole society. It began in the Roman Empire, conti ...

of the

Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Medit ...

canon law Canon law (from grc, κανών, , a 'straight measuring rod, ruler') is a set of ordinances and regulations made by ecclesiastical authority (church leadership) for the government of a Christian organization or church and its members. It is t ...

also contributed to the European ''ius gentium''. By the 16th century, the shared concept of the ''ius gentium'' disintegrated as individual European nations developed distinct bodies of law, the

authority In the fields of sociology and political science, authority is the legitimate power of a person or group over other people. In a civil state, ''authority'' is practiced in ways such a judicial branch or an executive branch of government.''The Ne ...

of the

Pope The pope ( la, papa, from el, πάππας, translit=pappas, 'father'), also known as supreme pontiff ( or ), Roman pontiff () or sovereign pontiff, is the bishop of Rome (or historically the patriarch of Rome), head of the worldwide Cathol ...

declined, and

colonialism Colonialism is a practice or policy of control by one people or power over other people or areas, often by establishing colonies and generally with the aim of economic dominance. In the process of colonisation, colonisers may impose their relig ...

created subject nations outside the West.

Roman law

classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations o ...

, the ''ius gentium'' was regarded as an aspect of

natural law Natural law ( la, ius naturale, ''lex naturalis'') is a system of law based on a close observation of human nature, and based on values intrinsic to human nature that can be deduced and applied independently of positive law (the express enacted ...

''( ius naturale)'', as distinguished from civil law ''(

ius civile Roman law is the legal system of ancient Rome, including the legal developments spanning over a thousand years of jurisprudence, from the Twelve Tables (c. 449 BC), to the ''Corpus Juris Civilis'' (AD 529) ordered by Eastern Roman emperor Justin ...

)''. The jurist Gaius defined the ''ius gentium'' as what "natural

reason Reason is the capacity of consciously applying logic by drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activities as philosophy, science, lang ...

has established among all peoples":

Every people ''(populus)'' that is governed by statutes and customs ''(leges et mores)'' observes partly its own peculiar law and partly the common law of all mankind. That law which a people established for itself is peculiar to it and is called ''ius civile'' (civil law) as being the special law of that ''
civitas In Ancient Rome, the Latin term (; plural ), according to Cicero in the time of the late Roman Republic, was the social body of the , or citizens, united by law (). It is the law that binds them together, giving them responsibilities () on the ...
'' (state), while the law that natural reason establishes among all mankind is followed by all peoples alike, and is called ''ius gentium'' (law of nations, or law of the world) as being the law observed by all mankind. Thus the Roman people observes partly its own peculiar law and partly the common law of all mankind.

As a form of natural law, the ''ius gentium'' was regarded as "innate in every human being", a view that was consonant with

Stoic philosophy Stoicism is a school of Hellenistic philosophy founded by Zeno of Citium in Athens in the early 3rd century BCE. It is a philosophy of personal virtue ethics informed by its system of logic and its views on the natural world, asserting that ...

Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the esta ...

distinguished between things that are written and those that are unwritten but upheld by the ''ius gentium'' or the ''

mos maiorum The ''mos maiorum'' (; "ancestral custom" or "way of the ancestors," plural ''mores'', cf. English "mores"; ''maiorum'' is the genitive plural of "greater" or "elder") is the unwritten code from which the ancient Romans derived their social norms ...

'', "ancestral custom". In his treatise ''

De officiis ''De Officiis'' (''On Duties'' or ''On Obligations'') is a political and ethical treatise by the Roman orator, philosopher, and statesman Marcus Tullius Cicero written in 44 BC. The treatise is divided into three books, in which Cicero expounds ...

'', he regards the ''ius gentium'' as a higher law of moral obligation binding human beings beyond the requirements of civil law. A person driven into exile, for instance, lost his legal standing as a

Roman citizen Citizenship in ancient Rome (Latin: ''civitas'') was a privileged political and legal status afforded to free individuals with respect to laws, property, and governance. Citizenship in Ancient Rome was complex and based upon many different laws, t ...

, but was supposed to retain the basic protections extended to all human beings under the ''ius gentium''. The 2nd-century Roman

jurist A jurist is a person with expert knowledge of law; someone who analyses and comments on law. This person is usually a specialist legal scholar, mostly (but not always) with a formal qualification in law and often a legal practitioner. In the U ...

Ulpian, however, divided law into three branches: natural law, which existed in nature and governed animals as well as humans; the law of nations, which was distinctively human; and civil law, which was the body of laws specific to a people.

Slavery Slavery and enslavement are both the state and the condition of being a slave—someone forbidden to quit one's service for an enslaver, and who is treated by the enslaver as property. Slavery typically involves slaves being made to perf ...

, for instance, was supported by the ''ius gentium'', even though under natural law all are born free (''liberi''). In this tripartite division of law,

property rights The right to property, or the right to own property (cf. ownership) is often classified as a human right for natural persons regarding their possessions. A general recognition of a right to private property is found more rarely and is typically ...

might be considered a part of the ''ius gentium'', but not of natural law. Hermogenianus, a Roman jurist of the second half of the 3rd century, described the ''ius gentium'' as comprising wars, national interests, kingship and sovereignty, rights of ownership, property boundaries, settlements, and commerce, "including contracts of buying and selling and letting and hiring, except for certain contractual elements distinguished through ''ius civile''". The ''ius gentium'' was thus in practice important in facilitating

commercial law Commercial law, also known as mercantile law or trade law, is the body of law that applies to the rights, relations, and conduct of persons and business engaged in commerce, merchandising, trade, and sales. It is often considered to be a branc ...

War, peace and the ''gentes''

The theory and terminology of

private law Private law is that part of a civil law legal system which is part of the ''jus commune'' that involves relationships between individuals, such as the law of contracts and torts (as it is called in the common law), and the law of obligations (a ...

was far more developed among the Romans than that of international law. The earliest form of international law was

religious Religion is usually defined as a social-cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...

and pertained to the concept of the "just war" ('' bellum iustum''), which should only be undertaken with a ritualized

declaration of war A declaration of war is a formal act by which one state announces existing or impending war activity against another. The declaration is a performative speech act (or the signing of a document) by an authorized party of a national government, ...

by the fetial priests. Foreign ambassadors were protected by the ''ius gentium'', and it was a religious violation to harm an envoy. While the terms of

peace treaties A peace treaty is an agreement between two or more hostile parties, usually countries or governments, which formally ends a state of war between the parties. It is different from an armistice, which is an agreement to stop hostilities; a surren ...

might be said to fall broadly within the ''ius gentium'', there was no framework of international law per se with which a treaty had to conform. As ''gentes'' were brought under Roman rule, Roman law became in effect international law. Local laws remained in force as long as they did not come into conflict with Roman law; this compatibility was understood as reflecting the underlying ''ius gentium''. The

praetor Praetor ( , ), also pretor, was the title granted by the government of Ancient Rome to a man acting in one of two official capacities: (i) the commander of an army, and (ii) as an elected ''magistratus'' (magistrate), assigned to discharge vari ...

assigned to foreign affairs ('' praetor peregrinus'') is thought by many scholars to have played an important role in extending Roman civil law to the ''gentes''. Laws originally pertaining to matters of contract law among Roman citizens, such as property transfers and

manumission Manumission, or enfranchisement, is the act of freeing enslaved people by their enslavers. Different approaches to manumission were developed, each specific to the time and place of a particular society. Historian Verene Shepherd states that ...

, were thus "internationalized" among the ''gentes''. Questions of "international law" might arise in relation to individual grants of citizenship, and whether these accorded with treaty. Because there was no generally accepted principle of international law, controversy might also arise over whether "Rome was bound by an agreement concluded by a field commander without approval of the Senate—typically an

armistice An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from the ...

concluded in distress and on unfavourable terms." A key passage pertaining to what Romans understood as "international law" is presented by

Livy Titus Livius (; 59 BC – AD 17), known in English as Livy ( ), was a Roman historian. He wrote a monumental history of Rome and the Roman people, titled , covering the period from the earliest legends of Rome before the traditional founding in ...

, as spoken by an envoy of King Antiochus:

There were three kinds of treaties (''foedera'', singular ''
foedus ''Foederati'' (, singular: ''foederatus'' ) were peoples and cities bound by a treaty, known as ''foedus'', with Rome. During the Roman Republic, the term identified the '' socii'', but during the Roman Empire, it was used to describe foreign sta ...
''), he said, by which states and kings concluded friendships (''amicitiae''): one, when in time of war terms (''leges'') were imposed upon the conquered; for when everything was surrendered to him who was the more powerful in arms, it is the victor's right and privilege to decide what of the conquered's property he wishes to confiscate; the second, when states that are equally matched in war conclude peace and friendship on terms of equality; under these conditions demands for restitution are made and granted by mutual agreement, and if the ownership of any property has been rendered uncertain by the war, these questions are settled according to the rules of traditional law or the convenience of each party; the third exists when states that have never been at war come together to pledge mutual friendship in a treaty of alliance; neither party gives or accepts conditions; for that happens when a conquering and a conquered party meet.

Terminology

Terminology associated with Roman international law was non-specialized but included: * ''Amicitia'', "a relation of friendship without any further concrete engagements, i.e. the mere exclusion of hostilities; … it could be concluded by a treaty but also without". * ''Societas'', although sometimes a mere synonym for ''amicitia'', is "an obligation to peace and neutrality" with "a duty to grant military support". * ''Foedus'', originally a sacred oath made by a fetial priest on behalf of the Roman people, who will suffer a "self-damnation" if they violate the treaty. * ''Pax'', "both the state of peace and the means to achieve it by treaty". * ''Indutiae'', "cease-fires" that "do not end the war as a whole, but interrupt the hostilities only temporarily". * ''Deditio'', surrender, with "the inherent normative expectation that the victor would in any case spare the inhabitants' lives". ** ''Dediticius'', a person who became a subject of the Roman Empire through a ''deditio''; ''dediticii'' were excluded from the universal citizenship extended to all free inhabitants of the empire under the ''

Constitutio Antoniniana The ''Constitutio Antoniniana'' (Latin for: "Constitution r Edictof Antoninus") (also called the Edict of Caracalla or the Antonine Constitution) was an edict issued in AD 212, by the Roman Emperor Caracalla. It declared that all free men in th ...

''. * ''Fides'', "trustworthiness, loyalty, credibility", was a quality the Romans wanted to pride themselves for upholding, including respect for the law and ''fides'' in foreign relations.

Medieval Europe

In the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

, the ''ius gentium'' derived from

in addition to Roman legal theory. In

late antiquity Late antiquity is the time of transition from classical antiquity to the Middle Ages, generally spanning the 3rd–7th century in Europe and adjacent areas bordering the Mediterranean Basin. The popularization of this periodization in English h ...

Isidore of Seville Isidore of Seville ( la, Isidorus Hispalensis; c. 560 – 4 April 636) was a Spanish scholar, theologian, and archbishop of Seville. He is widely regarded, in the words of 19th-century historian Montalembert, as "the last scholar of ...

(c. 560–636), enumerated the principles of the ''ius gentium'', focusing on ''foedera pacis'', "peace treaties":

''Ius gentium'' is occupation, construction, fortification, wars, captivity, the right of regaining citizenship after captivity, slavery, treaties, peace, armistice, the inviolability of ambassadors, the prohibition of mixed marriages; and it is the ''ius gentium'' because nearly every nation uses it.Isidore, ''Etymologies'' 5.6 ''(ius gentium est sedium occupatio, aedificatio, munitio, bella, captivitates, servitutes, postliminia, foedera pacis, indutiae, legatorum non violandorum religio, conubia inter alienigenas prohibita. Et inde ius gentium, quia eo iure omnes fere gentes utuntur)''; Winkel, "The Peace Treaties of Westphalia," p. 226.

References

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Roman law

War, peace and the ''gentes''

Terminology

Medieval Europe

References

Further reading