For the long succession of jurists reference must be made to the individual articles, but mention must be made here of the two "schools," the Sabinians (or Cassians) and the Proculians, into which they were divided in the early empire. Labeo (died between A.D. 10 and A.D. 22), one of the greatest figures in the history of jurisprudence, was the founder of the Proculians (who, however, took their name from a successor, Proculus) ; Capito, that of the Sabinians (so called from Massurius Sabinus, who was given the ins respondendi by Tiberius). What principles, if any, divided these schools, is unknown, though a number of controversies on particular points are preserved, especially in Gaius' Institutes. It is probable, though by no means certain, that there were teach ing establishments or societies of some sort in connection with the "schools," for otherwise the list of "heads" given by Pom ponius would be difficult to explain. The distinction does not seem to have survived the Antonine age ; for Gaius, a Sabinian, is the last jurist of whom we know that he belonged to one or other of the schools.
Constitutiones Principum.—Neither Augustus nor his immediate successors expressly assumed legislative power, and yet Gaius, writing about A.D. 16o, can say "there has never been any doubt that what the emperor lays down has the force of law." Ulpian, refers the validity of constitutions to the so-called lex regia, passed at the beginning of each emperor's reign ; and there is indeed in the only surviving example of such a lex (the lex de imperio Vespasiani line 17 seq., see Bruns Fontes p. 202) a clause conferring such wide powers on the emperor that legislation might be deemed to be included. Nevertheless it is now generally held that this was not the original meaning of the clause and that the emperor's legislative power is a gradual growth. The chief forms of imperial legislation were :—(a) Edicta, i.e., proclamations which the emperor, like other magistrates, might issue; but whereas the other magistrates were confined to their own spheres, the sphere of the emperor was in fact unlimited. (b) Mandata, i.e., instructions to subordinates, especially provin cial governors. (c) Rescripta, written answers to officials or others who have consulted the emperor, in particular on a point of law. In such cases the rescript lays down the point of law applicable and, since the emperor is supreme, the rule may be a new one.
(d) Decreta, i.e., decisions of the emperor sitting as a judge. Here too the emperor may lay down a new rule.
The Earlier Collections of Constitutions and the Legis lation of Justinian.—The growth of legal literature and espe cially of imperial constitutions created a need for works of reference which made itself felt long before Justinian, and a beginning was made, almost certainly in Diocletian's day, by a collection of constitutions known as the codex Gregorianus, which was followed by the codex Hermogenianus, perhaps also dating in its original form from Diocletian. Both collections were un
official, but their compilers must have had official countenance, for they clearly had access to the imperial archives. The Gregorianus contained constitutions from Hadrian to Diocletian, the Hermo genianus almost exclusively those of Diocletian's time; later constitutions attributed to it were probably only added in subse quent editions. It was clearly intended to supplement the Gregori anus. Unlike these two, the codex Theodosianus was an official work compiled by a commission appointed under Theodosius II. and Valentinian III., it was given the force of law as from Jan.
I, 439. Constitutions from the time of Constantine the Great onwards were, with very few exceptions, not to be valid unless contained in it. For the earlier imperial legislation the older codices still had to serve. Nearly the whole of the codex Theo dosianus has been preserved, whereas we only have fragments of the others. Theodosius had also planned a collection which would include juristic literature as well as imperial legislation, but this never came to fruition until it was taken up again by Justinian.
Justinian's Legislation.—(See also JUSTINIAN I.) Justinian's main object was, as he himself expresses it, to clear the path of legal authorities of the tangles with which it had become over grown during the course of centuries, and he set about the task almost immediately on ascending the throne. It must be noted however that he was no mere codifier, but also the author of much new legislation, some of which was of the utmost importance for the later development of law. The emperor was no doubt largely responsible himself for the work' undertaken, but it would probably not have been possible to carry it through but for the genius of his chief minister, Tribonian, who was clearly the leading spirit throughout the work. The course of legislation was as follows :— ( ) The Old Codex.—In Feb. 528, a commission of ten mem bers including Tribonian (who, however, was not president) was appointed to compile a new collection of imperial constitutions which was to supersede the older ones entirely and, of course, to include legislation subsequent to the Theodosian. The commis sioners were to cut out repetitions and contradictions and had large powers of alteration for this purpose. The work was rapidly done and published in April 529, with the force of law as from the i6th. It has not survived as it was later superseded.