As to the mode of collecting the opinions of the juris auctores no precise information has come down to us, but § 6 shows that the duty of the judex, in the not uncommon event of the authorities differing in their opinions on a case, was open to doubt, till Hadrian’s rescript allowed him under these circumstances to adopt the opinion he preferred. It may be gathered from the words ‘quorum omnium’ that all authorized jurists had to be consulted. The jus respondendi, as thus explained, may have continued in existence till the end of the third century, by which time the originative force of Roman jurisprudence had ceased. Instead of giving independent opinions jurists had become officials of the emperor, advising him in drawing rescripts and other affairs of imperial government. Legal authority rested in the writings of deceased juris auctores. (For a discussion of the causes of the decline of Roman Jurisprudence see Grueber’s Art. in Law Quarterly Review, vii. 70.) In the course of centuries the accumulation of juristic writings of co-ordinate authority was a serious embarrassment to the tribunals. To remedy this evil, a. d. 426, Valentinian III enacted what is called the law of citations, Cod. Theodosianus, 1, 4, 3, limiting legal authority to the opinions of five jurists, Gaius, Papinian, Ulpian, Paulus, Modestinus, and of any other jurists whom these writers quoted, provided that such quotations should be verified by reference to the original writings of these jurists (codicum collatione firmentur—on the question of the way of interpreting these words cf. Sohm, p. 122, n. 1, § 21). In case of a divergence of opinion, the authorities were to be counted, and the majority was to prevail. In case of an equal division of authorities, the voice of Papinian was to prevail. a. d. 533, Justinian published his Digest or Pandects, a compilation of extracts from the writings of the jurists, to which, subject to such modifications as his commissioners had made in them, he gives legislative authority. Every extract, accordingly, is called a lex, and the remainder of the writings of the jurists is pronounced to be absolutely void of authority. To prevent the recurrence of the evil which his codification was intended to remove, and confident in the lucidity and adequacy of his Digest and Code, which latter is a compilation of imperial statute law after the model of the Theodosian code, Justinian prohibits for the future the composition of any juristic treatise or commentary on the laws. If any one should disregard the prohibition, the books are to be destroyed and the author punished as guilty of forgery (falsitas), Cod. 1, 17, 2, 21. The constitutions enacted by Justinian subsequent to the publication of his code are called Novellae, Constitutiones or Novels.
We shall find frequent allusions, as we proceed in this treatise, to the existence of rival schools among the Roman juris auctores. This divergence of the schools dates from the first elevation of the jurist to a species of public functionary, namely, from the reign of Augustus, in whose time, as we have seen, certain jurists began to be invested by imperial diploma with a public authority. In his reign the rival oracles were M. Antistius Labeo and C. Ateius Capito: Hi duo primum veluti diversas sectas fecerunt, Dig. 1, 2, 47. ‘The first founders of the two opposing sects.’ From Labeo’s works there are 61 extracts in the Digest, and Labeo is cited as an authority in the extracts from other jurists oftener than any one else except Salvius Julianus. From Sempronius Proculus, a disciple of Labeo, and of whom 37 fragments are preserved in the Digest, the school derived its name of Proculiani. Other noted jurists of this school were Pegasus, in the time of Vespasian; Celsus, in the time of Domitian, who gave rise to the proverb, responsio Celsina, a discourteous answer, and of whom 141 fragments are preserved; and Neratius, of whom 63 fragments are preserved. To the other school belonged Masurius Sabinus, who flourished under Tiberius and Nero, and from whom the sect were called Sabiniani. To the same school belonged Caius Cassius Longinus, who flourished under Nero and Vespasian, and from whom the sect are sometimes called Cassiani: Javolenus Priscus, of whom 206 fragments are preserved: Salvius Julianus, the famous Julian, above mentioned, of whom 456 fragments are preserved: Pomponius, of whom 578 fragments are preserved: Sextus Caecilius Africanus, celebrated for his obscurity, so that Africani lex in the language of lawyers meant lex difficilis, of whom 131 fragments are preserved: and, lastly, our author, Gaius, who flourished under Hadrian, Antoninus Pius, and Marcus Aurelius, and from whose writings 535 extracts are to be found in the Digest.
If we now inquire whether this divergence of schools was based on any difference of principle, the answer is, No: on none, at least, that modern commentators have succeeded in discovering: it was merely a difference on a multitude of isolated points of detail. We are told indeed that the founders were men of dissimilar characters and intellectual dispositions: that Labeo was characterized by boldness of logic and a spirit of innovation; while Capito rested on tradition and authority, and inclined to conservatism, Dig. 1, 2, 47; but it is altogether impossible to trace their opposing tendencies in the writings of their successors: and we must suppose that the intellectual impulse given by Labeo was communicated to the followers of both schools of jurisprudence. But though, as we have stated, no difference of principle was involved, each school was accustomed to follow its leaders or teachers (praeceptores) with much servility; and it is quite an exception to find, on a certain question, Cassius, a member of the Sabinian school, following the opinion of Labeo; while Proculus, who gave his name to Labeo’s school, preferred the opinion of Ofilius, the teacher of Capito, 3 § 140; Gaius too, who was a Sabinian, sometimes inclines to the opinion of the rival school; cf. 3, § 98. Controversies between the two schools are referred to by Gaius in the following passages of his Institutes: 1, 196; 2, 15, 37, 79, 123, 195, 200, 216-222, 231, 244; 3, 87, 98, 103, 141, 167-8, 177-8; 4, 78-9, 114, 170.
As long as these schools of law, which may have derived their constitution from the Greek schools of philosophy, existed, the office of President appears to have devolved by succession from one jurist to another. (For an account of this subject and references to the chief modern writers who have discussed it see Sohm, pp. 98, &c.)
We may briefly mention some of the most illustrious jurists who flourished somewhat later than Gaius. Aemilius Papinianus, who was probably a Syrian, lived in the time of Septimius Severus, and was murdered by the order of Caracalla: 601 extracts from his writings are contained in the Digest. It was perhaps to some extent due to the transcendent genius, or at least to the extraordinary reputation, of Papinian, which made him seem too great to be reckoned any man’s follower, that we cease about his time to hear of opposing schools of jurisprudence. Papinian appears to have accompanied Severus to York, fulfilling the important function of praefectus praetorio, so that England may claim some slight connexion with the brightest luminary of Roman law.
A disciple and colleague of Papinian, of Syrian origin, who likewise became praefectus praetorio, was Domitius Ulpianus, murdered by the praetorian soldiery, whose domination he resisted, in the presence of the Emperor Alexander Severus: 2464 fragments, composing about a third of the whole Digest, are taken from his writings. An epitome of his Liber Singularis Regularum is still extant in a manuscript of the Vatican Library, and is the work referred to when, without mentioning the Digest, we cite the authority of Ulpian.
Another disciple and colleague of Papinian was Julius Paulus, of whose writings 2081 fragments are preserved