I. ARCHAIC PERIOD (753 B.C. to ca. 300 B.C.)

unwritten custom (mos majorum), administered only by the Patricians (consuls, praetors, pontiffs).

The XII Tables (rustic, agricultural, heavy penalties, debt slavery, self-help, patron-client relationships).

II. FORMATIVE PERIOD (ca. 300 B. C. to 30 B.C.)

`Formulas' for conducting legal cases (actiones) are published for the first time.
Statute law, passed by assemblies, becomes significant; professional oratory begins to enter Rome (II-I cents. B.C.), practice from Greek educators; the politician-orator (e.g. Cicero).
Professional juristic consultors set up in business and begin to write books (I cent. B.C.).
Collapse of the Republic (49-30 B.C.) ends the Republican system.

III. CLASSICAL PERIOD (ca. 30 B.C. to ca. 250 A.D.)

begins with the creation of the office of Emperor (PRINCEPS, the `First Citizen'), who has legal advisors among the members of his advisory council (Consilium Principis).

The Emperor authorizes certain jurisconsults to issue formal decisions which can create precedents in the courts. The Emperor becomes a court-of-appeal for all the provinces under his control (and others).

His PREFECT-OF-THE-PRAETORIAN GUARD takes on more and more of the actual appeal business (including that from the Roman Army) until, by the Third Century A.D. the Prefect is first and foremost a judicial official. The Senate becomes a court to hear cases of provincial maladministration by Senators (under AUGUSTUS).

The Emperor HADRIAN (117-138) had the RULES OF PROCEDURE used by the various Praetors in the law courts in Rome drawn together in their final authoritative form. Legal scholars founded schools , both at Rome (Sabinus, Cassius) and in the provinces, especially at BEIRUT. Writers on law: ULPIAN, GAIUS. The period gradually closes by the mid-III century, with the chaos of civil war and economic collapse.

IV. PERIOD OF CODIFICATION (IV-VI centuries)

in which authoritative handbooks and standard collections are issued under imperial sponsorship.

Codex Theodosianus (Emperor THEODOSIUS II, 408-450)

a collection of all laws issued since 312 A.D. (accession of Constantine). This added to the older semi-official efforts: Codex Gregorianus (291) and Codex Hermogenianus (ca. 295).

Codex Justinianus (Emperor JUSTINIAN, 527-565) a new collection made by Tribonian and a commission of experts; only the 2nd edition (534) survives. This superseded all earlier codes. It contained some 5000 decisions, from the time of HADRIAN (117) to that of JUSTINIAN.

A Supplement had to be issued even in the reign of Justinian; it was called the Novellae For the benefit of students, the imperial commission also issued, on November 21, 533 A.D., an official textbook of Roman Law, called the Institutes of Justinian, which was itself given the force of law. This was necessary since it was forbidden to engage in writing commentaries on the Codex Justinianus.

The habit of codifying laws into official codexes strongly influenced the medieval Catholic Church, and eventually collections of church laws (called Canons) were made. Collectively these came to be called the Corpus Juris Canonici, and they still influence the operations of the Roman Catholic Church, the Anglican Church, the Orthodox Churches and others. Up to the 20th century, the laws of Justinian could be used in German and South African courts, and most law systems which are based on the French Code Napoleon have been strongly influenced by Roman civil law. This includes the State of Louisiana (once a French colony, to 1803), whose Constitution was based on the Code Napoleon.