Systems

Fas / Nefas

Archaic Period. Fas was the religious side of archaic law: any conduct in line with the gods' will, which kept the city in their favor. Nefas was conduct against fas, such as high treason, using sacred places for secular purposes, or holding a trial on a forbidden day. Because nefas damaged the city's relationship with the gods, it could bring disaster on society as a whole. At first, fas and ius were handled by the same priestly college, the pontiffs.

Mos maiorum

Archaic Period (Monarchy), and it remained the oldest layer of the ius civile in the Republic. It means "the customs of the elders": the unwritten, long-standing usages of the Roman community. It was built on values such as fides (good faith), pietas (duty), dignitas (dignity) and disciplina (discipline). It developed from disputes brought before clan patriarchs and the king. Ius grew out of it, and it became the first of the three layers of the ius civile.

Ius (vs. iniuria)

Archaic Period. Ius was the secular law governing relationships between citizens, rooted in the mos maiorum. Conduct that wronged a fellow citizen violated ius and was called iniuria; unlike nefas, it affected only individuals, not the whole community. It still had some religious ties: obligations fell under fides ("good faith"), an attribute of Jupiter. The gradual separation of ius from fas made law a secular order, which is considered archaic Rome's greatest legal achievement.

Patria potestas (paterfamilias)

Archaic Period, with influence lasting into later eras. It was the power of the paterfamilias (head of the household) over his family. In archaic Rome's rural, patriarchal society, he effectively owned his wife, children, slaves and livestock. He alone had legal capacity and the full right to act: his wife and children depended on him even as adults, and slaves were treated as "things". It left a lasting mark on family and property law, for example the French Civil Code's "bon père de famille" standard. It was softened later under Christianity.

Leges regiae

Archaic Period (Monarchy, until 509 BC). These were the "royal laws" attributed to Rome's early kings. They were not truly new laws but glosses (written notes) on existing customary law. For example, a law of Romulus forbade a wife to divorce her husband, and a law of Numa said a paterfamilias could not sell his son into slavery after allowing him to marry.

Pontifical responsa

Archaic Period (until the 3rd century BC). These were the legal answers given by the pontiffs (pontifex, "bridge-builder"), the patrician-only priestly college that controlled both fas and ius. Citizens brought legal questions to a pontiff, who, like an oracle but without ambiguity, gave a brief, precise answer for that specific case. This question-and-answer method became the core method of Roman law and gave it its casuistic (case-by-case) character. The pontiffs preserved, interpreted and applied the law until lay jurists replaced them in the 3rd century BC.

Mancipatio and Stipulatio

Archaic Period, and both survived into later Roman law. Mancipatio was originally the only way to transfer ownership of important goods (Italic land, slaves, cattle). It was a ritual: the new owner seized the object in front of the owner, a copper or bronze coin was weighed on a scale before five adult witnesses, and set words were spoken. Its legal effect came from performing the ritual correctly, not from the parties' intentions. Stipulatio was the oldest Roman contract, made by a rigid exchange of question and answer. Both show the formalism of archaic law, which copied the exact ritual of religion.

Legis actiones

Archaic Period, used into the Republic and almost forgotten by its end. These "actions of the law" were the earliest Roman civil procedure, inherited from the pontiffs. They were rigid and ritualized: one wrong word, such as "vine" instead of "tree," invalidated the case. Only a limited number of actions existed, so a claim that didn't fit one had no legal protection. They were gradually replaced by the more flexible formulary procedure.

Law of the Twelve Tables

Archaic Period (early Republic, c. 451–450 BC). Rome's first written legal code, created because plebeians demanded to know the law, which had been kept secret by the patrician pontiffs. It wrote down the secular heritage of pontifical law on 12 bronze tablets displayed in the Forum. It covered mainly private and procedural law, including procedure, debt, paternal authority, property, inheritance, funerals and offenses, but nothing on how the state was organized, so it was not a constitution. It made law public, specific and rational, for example by requiring a trial before anyone could be executed. The tablets were lost in a fire in 380 BC.

Ius civile (archaic sense)

Archaic Period, consolidated by the 3rd century BC. It means "the law of the citizens": the core of Roman private law, applying in principle only to Roman citizens. By the 3rd century BC it had three layers: the mos maiorum (custom), the Twelve Tables (written law) and the responsa (expert answers). It was mostly casuistic, and old rules were never repealed; new ones were simply added on top.

Jurists' responsa

Late Republic, continuing into the Principate. From the 3rd century BC, lay jurists took over the pontiffs' role and their responsa method. Their opinions were not legally binding, but they carried great auctoritas (social and moral prestige) and served as precedents. They never charged fees and did not act as advocates. Cicero described their three roles as cavere (drafting legal documents), agere (advising during lawsuits) and respondere (answering legal questions).

Leges (e.g. Lex Aquilia)

Republic (the Lex Aquilia dates from c. 287/286 BC). Leges were laws passed by the popular assemblies, mostly on public and criminal law, with little effect on private law. The main exception was the Lex Aquilia on wrongful damage (tort). Under it, killing another person's slave or cattle meant paying its highest value in the previous year, and other damage (burning, breaking, spoiling) meant paying its value within 30 days. It was casuistic rather than a general principle, and praetors extended it to new cases by analogy

Ius gentium

Republic (arose with Rome's expansion and the arrival of foreigners). It means "the law of peoples": law created by the Romans, using Roman categories, to settle disputes involving foreigners. It was not international law in the modern sense of law between nations. It was a general system of private law based on fairness and reason, which is why later jurists linked it with ius naturale (natural law). It was administered mainly by the praetor peregrinus.

Formulary procedure (per formulas)

Republic, used until it was replaced under the Dominate. A flexible civil procedure developed by the praetor peregrinus for foreigners and later extended to citizens; it replaced the legis actiones. In the first phase (in iure), the praetor reviewed the claim and wrote a formula: binding instructions to the judge, such as "If it is proven that the defendant owes 10,000 sesterces, condemn him; if not, acquit him". The formula was then recorded before witnesses (litis contestatio), which fixed the dispute so it could not be brought again. In the second phase (apud iudicem), a private lay judge examined the facts and ruled strictly within the formula, with no appeal. Its main advantage was flexibility.

Praetorian edict

Republic. A public program each praetor published when he took office, listing the remedies he would grant during his one-year term, displayed on whitewashed tablets in the Forum. In theory each praetor could rewrite it completely, but in practice they kept most of their predecessors' content and added changes suggested by jurists. This balance between tradition and innovation drove the remarkable development of Roman law.

Ius honorarium / Ius praetorium

Republic, later fixed in the Principate by the Edictum perpetuum. The body of law formed by the edicts of the praetors (ius praetorium) or of all magistrates (ius honorarium, from honores, "magistracies"). It eventually became a complete legal system. It did not replace the ius civile; it supplemented and adapted it, out of respect for the archaic core.

Ius civile (two meanings)

Republic. In its first meaning, ius civile is the archaic core (mos maiorum, the Twelve Tables and the pontifical responsa) as opposed to the ius honorarium. In its second meaning, it is all the law peculiar to Roman citizens (ius proprium civium Romanorum), including the ius honorarium, as opposed to the ius gentium. It is also called ius Quiritium, from Quirites, meaning Roman citizens.

Edictum perpetuum

Principate (Hadrian, c. AD 138). The "Perpetual Edict": the final, fixed version of the praetor's edict, drafted by the jurist Salvius Julianus on Hadrian's orders. The edict had become so refined that changes were rarely needed. It showed that praetors no longer drove the evolution of law; from then on, jurists and the emperor did.

Ius respondendi (ex auctoritate principis)

Principate (early emperors, until the late 2nd century). A privilege the emperor granted to the most eminent jurists to give responsa on his authority. Officially these opinions were still not binding, but judges rarely departed from them. It combined the emperor's charisma with the jurists' auctoritas, raising the prestige of both and letting emperors quietly control how the law developed. It became unnecessary once top jurists sat permanently on the imperial council.

Rescripta

Principate, continuing into the Dominate. The emperor's written answers to legal questions sent from across the Empire, prepared by his council of jurists. The answer was written on the same document as the request, hence re-scripta. In principle they had no legal validity, but because of the emperor's authority they were followed in most cases.

Classical jurisprudence

Principate (peak during the Pax Romana). The golden age of Roman legal science, when jurisprudence was the most important source of law. It is called "classical" because of the extraordinary perfection of its style. It was casuistic and practical, and wary of abstract definitions ("every definition is dangerous"). Systematization began with Gaius's Institutiones (persons, things, actions), and the great jurists included Labeo, Julian, Gaius, Papinian, Ulpian, Paulus and Modestinus.

Universal citizenship (AD 212)

Principate (Caracalla). Emperor Caracalla granted Roman citizenship to all free inhabitants of the Empire, mainly so he could tax more people. This made Roman law universal, a key step toward legal and territorial unity. It also increased demand for trained jurists.

Constitutiones imperiales

Dominate. Imperial legislation issued directly by the emperor as edicta, decreta and rescripta. In the 4th and 5th centuries, under absolute monarchy, it became almost the only source of law. It was written in a pompous, commanding style, very different from classical elegance, and the emperor became "the mainspring of law".

Cognitio

Dominate (it began in the Principate and became standard under the Dominate). "Outside the ordinary process": a new civil procedure that started in the provinces. State officials ran the whole case in a single stage, removing the private judge and the two-phase structure. No specific remedy was needed, so it became a general way to seek justice. Because it was written and hierarchical, losing parties could appeal to the emperor. It replaced the formulary procedure and is the ancestor of modern civil procedure.

Vulgar law

Dominate (post-classical law). The simplified, weakened law of the post-classical period, after jurisprudence declined under imperial control. It had three tendencies: simplifying anything too complex, judging law by its economic and social effects, and seeking morally just results with little regard for form. Its symbol is directum ("the straight way"), the origin of the words derecho, droit and diritto.

Law of Citations

Dominate (AD 426; the chapter credits Theodosius II, the slides Valentinian III). A law allowing only five classical jurists to be cited in court: Papinian, Paulus, Gaius, Ulpian and Modestinus. If they disagreed, the majority won; in a tie, Papinian's view won; and if Papinian said nothing, the judge chose. It responded to the problem of too many legal writings that were hard to find and contradicted each other. It failed because counting votes was arbitrary, but it shaped the later Digest.

Codex

Dominate (AD 439, Emperor Theodosius II). An official collection of imperial laws, smaller in scope than Justinian's later work.

Corpus iuris civilis

Justinian (6th century AD). The name used since the 15th century for Justinian's codification, made up of four books: the Institutiones, Digest, Codex and Novellae. It was prepared by a commission led by Tribonian, whose members were called "compilers" because they selected and arranged old texts rather than writing new law. It is the main source of what we know about Roman law, and from the 11th century it became Europe's greatest legal authority.

Institutiones (Justinian)

Justinian (AD 533). A short introductory textbook for law students, given the force of law and modeled on Gaius's Institutiones. It has four books: Persons, Things (property and inheritance), Things (obligations: contracts and delicts) and Actions. Its structure inspired modern civil codes such as the French Code civil (1804) and the German BGB

Digest

Justinian (AD 533). An anthology of excerpts from classical jurists in 50 books, with fragments from 39 jurists. The compilers read over 2,000 scrolls and kept about 5%. They altered the texts through "interpolations" to remove contradictions and update terms. It is arranged by topic and was given the force of law, and Justinian banned commentaries on it.

Codex

Justinian (first version AD 529, final version 534). An official collection of imperial laws from Hadrian onward, keeping only those still useful. It was divided into 12 books, in tribute to the Twelve Tables, covering church law, sources of law, administrative, private, criminal and tax law. It was binding law aimed at judges and officials.

Novellae

Justinian (laws issued after AD 534). "New laws" issued by Justinian and his immediate successors after the Codex was published. They added to, changed or clarified existing law to meet new needs in areas such as the church, family, succession and procedure. They were never officially compiled, only gathered in private collections.

Romano-canonical procedure

Late Middle Ages (built on the Dominate's cognitio). The civil procedure used in the courts of the Late Medieval Church, which revived the Roman cognitio. It spread across Europe as the ordinary way to administer civil justice. With some adjustments in the 19th century, it is essentially the civil procedure we use today.