The Roman law proper, the jus civile, had multifarious sources. First the leges, enacted by the people; then the plebiscita, sanctioned by the Plebs; the senatus consulta, passed by the Senate; the constitutiones and rescripta[345] principum, ordained by the Emperor. Excepting the rescripta, these (to cover them with a modern expression) were statutory. They were laws announced at a specific time to meet some definite exigency. Under the Empire, the constitutiones principum became the most important, and then practically the only kind of legal enactment.
Two or three other sources of Roman law remain for mention: first, the edicta of those judicial magistrates, especially the praetors, who had the authority to issue them. In his edict the praetor announced what he held to be the law and how he would apply it. The edict of each successive praetor was a renewal and expansion or modification of that of his predecessor. Papinian calls this source of law the “jus praetorium, which the praetors have introduced to aid, supplement, or correct the jus civile for the sake of public utility.”
Next, the responsa or auctoritas jurisprudentium, by which were intended the judicial decisions and the authority of the legal writings of the famous jurisconsults. Imperial rescripts recognized these responsa as authoritative for the Roman courts; and some of the emperors embodied portions of them in formally promulgated collections, thereby giving them the force of law. Justinian’s Digest is the great example of this method of codification.[346] One need scarcely add that the authoritative writings and responsa of the jurisconsults extended and applied the jus gentium, that is to say, the rules and principles of the best-considered jurisprudence, freed so far as might be from the formal peculiarities of the jus civile strictly speaking. And the same was true of the praetorian edict. The Roman law also gave legal effect to inveterata consuetudo, the law which is sanctioned by custom: “for since the laws bind us because established by the decision of the people, those unwritten customs which the people have approved are binding.”[347]
Simply naming the sources of Roman law indicates the ways in which it grew, and the part taken by the jurisconsults in its development as a universal and elastic system. It was due to their labours that legal principles were logically carried out through the mass of enactments and decisions; that is, it was due to their large consideration of the body of existing law, that each novel decision—each case of first impression—should be a true legal deduction, and not a solecism; and that even the new enactments should not create discordant law. And it was due to their labours that as rules of law were called forth, they were stated clearly and in terms of well-nigh universal applicability.
The Laws of the Twelve Tables showed the action of legal intelligence and the result of much experience. They sanctioned a large contractual freedom, if within strict forms; they stated broadly the right of testamentary disposition. Many of their provisions, which commonly were but authoritative recognitions, were expressions of basic legal principles, the application of which might be extended to meet the needs of advancing civic life. And through the enlargement of this fundamental collection of law, or deviating from it in accordance with principles which it implicitly embodied, the jurists of the Republic and the first centuries of the Empire formed and developed a body of private and public law from which the jurisprudence of Europe and America has never even sought to free itself.
Roman jurisprudence was finally incorporated in Justinian’s Digest, which opens with a statement of the most general principles, even those which would have hung in the air but for the Roman genius of logical and practical application to the concrete instance. “Jus est ars boni et aequi”—it is better to leave these words untranslated, such is the wealth of significance and connotation which they have acquired. “Justitia est constans et perpetua voluntas jus suum cuique tribuendi. Juris praecepta sunt haec: honeste vivere, alterum non laedere, suum cuique tribuere. Jurisprudentia est divinarum atque humanarum rerum notitia, justi atque injusti scientia.”
The first pregnant phrase is from the older jurist Celsus; the longer passage is by the later Ulpian, and may be taken as an expansion of the first. Both the one and the other expressed the most advanced and philosophic ethics of the ancient world. They are both in the first chapter of the Digest, wherein they become enactments. An extract from Paulus follows: “Jus has different meanings; that which is always aequum ac bonum is called jus, to wit, the jus naturale: jus also means the jus civile, that which is expedient (utile) for all or most in any state. And in our state we have also the praetorian jus.” This passage indicates the course of the development of the Roman law: the fundamental and ceaselessly growing core of specifically Roman law, the jus civile; its continual equitable application and enlargement, which was the praetor’s contribution; and the constant application of the aequum ac bonum, observed perhaps in legal rules common to many peoples, but more surely existing in the high reasoning of jurists instructed in the best ethics and philosophy of the ancient world, and learned and practised in the law.
Now notice some of the still general, but distinctly legal, rather than ethical, rules collected in the Digest: The laws cannot provide specifically for every case that may arise; but when their intent is plain, he who is adjudicating a cause should proceed ad similia, and thus declare the law in the case.[348] Here is stated the general and important formative principle, that new cases should be decided consistently and eleganter, which means logically and in accordance with established rules. Yet legal solecisms will exist, perhaps in a statute or in some rule of law evoked by a special exigency. Their application is not to be extended. For them the rule is: “What has been accepted contra rationem juris, is not to be drawn out (producendum) to its consequences,”[349] or again: “What was introduced not by principle, but at first through error, does not obtain in like cases.”[350]
These are true principles making for the consistent development of a body of law. Observe the scope and penetration of some other general rules: “Nuptias non concubitus, sed consensus facit.”[351] This goes to the legal root of the whole conception of matrimony, and is still the recognized starting-point of all law upon that subject. Again: “An agreement to perform what is impossible will not sustain a suit.”[352] This is still everywhere a fundamental principle of the law of contracts. Again: “No one can transfer to another a greater right than he would have himself,”[353] another principle of fundamental validity, but, of course, like all rules of law subject in its application to the qualifying operation of other legal rules.
Roman jurisprudence recognized the danger of definition: “Omnis definitio in jure civili periculosa est.”[354] Yet it could formulate admirable ones; for example: “Inheritance is succession to the sum total (universum jus) of the rights of the deceased.”[355] This definition excels in the completeness of its legal view of the matter, and is not injured by the obvious omission to exclude those personal privileges and rights of the deceased which terminate upon his death.