Coming to Grips with Roman Law

How to understand this cornerstone of Western civilization

From A Common Law [1]

Rome arose, a republic – that is, a polis, a city-state like the Greek city-states – but a republic with a difference. Rome reigned, not by crushing its rivals, but by coopting them. It joined with its sister republics in a federal union. In developing the federal principle Rome enabled the rule of law to gain universal validity and universal application. Roman law bound cities and nations into a single civilization, something Hellenism never accomplished due to its union based in divine kingship rather than the rule of law.

The Roman law has often been characterized as an instrument of absolute sovereignty, with maxims like princeps legibus solutus, “the prince is free of the laws,” and quod principi placuit legis vigorem habet, “what pleases the prince has the force of law.” But, as McIlwain has pointed out,[2] the essence of the Roman law lay not in such statements so much as in the priority of private law to public law, no matter how conceived. Roman law derives public law from private law; the citizen is antecedent to the state; the state serves to preserve and protect the citizen in his rights, and not vice versa. The pillars of Roman law are the household, private property, and market exchange, the very elements which make up the Aristotelian citizen ideal. Roman law establishes and regulates human relations in terms of these basic categories. Rome was able to establish and maintain its empire over diverse and numerous peoples and territories because its law was received as an advance over what was there before it. By it, the peoples were net gainers; its universality and simplicity likewise enabled their integration into a common civilization.

The imperial dream of universal domination came to an end with the interregnum which followed the death of Frederick II in 1250. But this by no means spelled the end of the imperial ideal. In fact, it was the necessary condition for the appearance of something entirely new, a resurrected, redeemed imperial ideal, an ideal of a respublica Christiana, a unified body of Christian republics sharing one law, one faith, one civilization.[3] The law of that empire, the Roman law, was subjected to the same process of regeneration, enabling it to become something other and greater than it had ever been before. From being the law of a single sovereign, it was transformed into a universal law-order which set boundaries to all sovereigns and established a framework for mutual exchange and communication, the ligaments binding them together.

What happened to the Roman law is best described as a shift in emphasis from civil law to common law, jus civile to jus commune (also known as jus gentium, “law of nations”). Civil law, jus civile, refers to Roman law as the law of Rome the city/state/empire – and, by extension, Roman law as the internal law of a sovereign polity. Common law, jus commune, refers by contrast to Roman law as a framework for a universal law-order, a law between sovereigns.

This is the “common law” referred to in the title of the book – the constitutional framework of nationhood. In it was comprehended the synthesis of objective and subjective aspects of liberty.

The common law had always been something of the poor relation in the Roman-legal structure, because it dealt with cases on the periphery of the Roman-legal horizon. Developed on an ad-hoc basis, it the law applied in Roman law courts to cases involving foreigners or between Roman citizens and foreigners. Its main concern therefore was private law. Its basis was the emerging conviction that a universal law-order actually existed. Not a speculative conviction of the Stoic variety, though, but a conviction arising from concrete experience. “Because one realized that purchase and work agreements, agreements to borrow money and contract out work and suchlike were also made and carried out by other peoples, one assumed that the obligations stemming from such agreements rested on juridical principles valid everywhere in the same way.”[4] Using a hard-nosed, inductive approach to the demands brought by the administration of their burgeoning empire, Roman judges and jurists gradually developed the body of legal principles known originally as the jus gentium and eventually as the jus commune. What they did was to apply the Roman-legal principles of the civil law to the changed circumstances brought on by an intercultural situation. “In the form of the jus gentium, Roman law emerged from its restricted area of validity, the community of Roman citizens.”[5] By the latter half of the second century Roman jurists had developed a comprehensive definition:

All peoples with laws and customs apply law which is partly theirs alone and partly shared by all mankind. The law which each people makes for itself is special to its own state. It is called ‘state law’ [jus civile], the law peculiar to that state. But the law which natural reason makes for all mankind is applied the same everywhere. It is called ‘the law of all peoples’ [jus gentium] because it is common to every nation.[6]

The knowledge of the existence of this law was carried into the middle ages by the seventh-century churchman Isidore of Seville, who included the Roman-law trichotomy of natural law, civil law, and the law of nations in his compendium Etymologiarum sive Originum Libri XX. Its Roman-legal content regained importance with the revival of Roman-law teaching in the 11th century. It became a basic category of canon law and also, through Thomas Aquinas, moral law. It began to gain ascendancy among Roman lawyers after the collapse of imperial power and consequent lack of the ability to enforce the jus civile strictly speaking. Roman law henceforth began to be interpreted along the lines of jus gentium or jus commune, as the common law of Christendom, rather than as the law of an imperial state.

It was in Italy, the cradle of imperial legal science, that jurists in the early 14th century began to reinterpret Roman law in terms of jus commune rather than jus civile. They did so because the Italian cities had in effect thrown off imperial sovereignty, but nevertheless acknowledged a vague imperial supremacy. The leading figure in this reinterpretive effort was Bartolus of Saxoferrato (1314-1357). Bartolus maintained the idea of the empire as a theoretical construct; this justified his adherence to Roman law as binding law. But his intention was different: the adaptation of that law to actual Italian conditions. Using Roman public-law concepts of sovereignty, he fashioned a theory which recognized the rights of self-government of the Italian cities, attributing to them a relative sovereignty, while retaining nominal allegiance to the emperor as overlord. The result was a theory of a “hierarchy of sovereignty,”[7] a budding federalism in which lower levels of government were recognized as having legitimacy in their own right rather than as mere creatures of a sovereign overlord.

What then was the source of this legitimacy? As the Roman lawyers began to claim, it was the jus gentium itself: “According to [Bartolus’s student] Baldus natural reason in the form of its product, the ius gentium, not only brought city-populi into existence, but endowed them with autonomous powers of self-government without the need for the authorisation of a superior: the foundation upon which the argument for their sovereignty could be built.”[8] The common law was emerging from the shadows of the civil law and taking on the shape of constitutional law, a law which defined and established public authority and private rights. The common law was replacing the civil law as the law-order expressive of the imperial ideal; the emperor was becoming a guarantor of a universal law-order embracing and restricting sovereigns, rather than an overlord of tribute-paying subjects.

Did not this constitute the reversal, indeed the overthrow of the foundations of government as described earlier? Ullmann attributed to Bartolus’s doctrine of popular sovereignty precisely such a significance: “Authority stemmed from the people, and not from a ‘superior’ authority…. It was no longer the superior insight of the Ruler which determined what was in the interests of the people, but the people itself was recognized as perfectly capable of forming its own judgement on what was in its interests…. Once again we meet the concession principle, though in an inverted sense….”[9] But Bartolus had in mind an incipient federalism, a “hierarchy of sovereignty” whose ground rules were laid up in a universal law-order, the common law. Within this law-order room existed for both bottom-up, popular civil government and top-down, divine-right royal government. Such a system would require a delicate balance, a balance which, as it happened, was actually struck as the tradition of imperial common-law jurisprudence came to maturity. For no jurisdiction was certain which was not recognized by the sovereign power; it was the primary function of the emperor not to establish jurisdiction but to recognize it, to grant through the instrument of chartered liberties the legitimacy lower jurisdictions needed in the face of the world at large. This was the security and stability provided by the emperor to Germany in a period when it otherwise would have collapsed into its member components, as in fact happened in Italy.

Chartered liberties were an essential element of the development of institutions of freedom. They formed the warp and woof of the Western constitutional order. They arose out of the historical give-and-take between ruler and subject. They are thus the product of the historical process generated by the interaction of the objective and subjective aspects of freedom. They are also therefore the fruit of Christian civilization. With the elimination of public Christianity came likewise the transformation of rights, as we shall see.

The opposite course was taken in medieval France, where a school of jurisprudence took root whose center of gravity lay in establishing the juridical foundations for an independent, supreme monarchy, over against the emperor, the pope, and feudal barons. The jurists’ key formula was rex in regno suo est imperator regni sui: “The king is the emperor in his kingdom.” Thus the French king was the equal of the emperor, occupying the same position within the Roman law as the emperor. In this manner the French king and his jurists appropriated the interpretive tradition of the civil law, just as that tradition collapsed in the empire proper. It was France which would carry on the tradition of sovereign overlordship, with momentous consequences for the future.

Here dawns a divergence in the course of Western sociopolitical institutions, embodied in Germany on the one hand and France on the other: the prolegomena to the divergence between the common-law and the civil-law traditions.

(pp. 53–56.)

The priority, at least chronological, of the constitutional conflict can be seen even in the work of John Calvin himself. Before going over to the side of the Reformation, Calvin penned a learned commentary on Seneca’s De Clementia, a work which gave clear expression to his constitutionalism. Calvin directed his arrows against the juristic school of Toulouse, which “even more than the legists of the thirteenth century [see above] interpreted Roman law in an absolutist sense,” and against its “theoretical support for the centralist-absolutist state of Francis I.”[10] In Bohatec’s words, “[Calvin’s] Seneca commentary signals the young humanist’s open war against the absolutist claims of the government of his homeland.”[11] 

Not that Calvin rejected Roman law. He found himself on the other side of the great divide in Roman-legal interpretation; he was a common-law man. “When [Calvin] lashes out against the contempt shown for the communes leges gentium [i.e., common law of nations] by its opponents, judging such contempt to be folly, he doubtless had the Roman law in mind, since at the time this law enjoyed the status of universal law over against the civil laws of particular territories.”[12] His comments in favor of the common law are to be found in the famed 20th chapter of the fourth book of his Institutes of the Christian Religion, which deals with civil government, and appeared in the first edition of 1536 as well as every subsequent edition.

(pp. 73–74)

From Fountainhead of Liberalism

What we must keep in mind is that many of the great thinkers of the sixteenth and seventeenth centuries received Roman-legal training, often receiving degrees utriusque (in both civil and canon law), and this holds true for many of the Reformers. John Calvin, Theodore Beza, Lambert Daneau, Johannes Althusius, and François Hotman were all trained in Roman law, and Althusius was a professor of Roman law. I do not believe we can overestimate the significance of this. Roman law provided a paradigm of forensic/judicial thinking which has permeated Western theology (judicial theology) and philosophy from the beginning. The founder of Latin theology, after all, was Tertullian, a Roman jurist by profession.[13]

Hostility to the Roman legal tradition among modern Christians is also endemic. Although understandable, it is rooted in ignorance as to what that tradition entails. The hostility, as one might guess, stems directly from the Whig Interpretation of History, which in legal history comes in the form of the Common Law Mind.[14] For English common lawyers, “The enemies at the gates…were those twin menaces, civil and canon law, which – coiled like two snakes about Mercury’s wand, as Selden put it – Englishmen tended to regard with a sort of fascinated horror.”[15] The immediate cause of the hostility to Roman law which has always been part and parcel of conservative Whiggery was the use to which it was put in the service of absolute monarchy. To that degree the criticism is justified. But we need to keep in mind McIlwain’s conclusion: “The fundamental doctrine underlying the Roman state, its true guiding spirit, is constitutionalism, not absolutism…. The really decisive influence of Rome on later European politics came, not after the Italian Renaissance in the tendency toward absolutism, but during the middle ages in the reinforcement of constitutionalism.”[16] One thing the keepers of the Common Law Mind often forget is that Roman jurisprudence presided at its inception, represented in such figures as Glanvill and Bracton.

From The Roman-Law Background of the Concept of Equity

Equity makes its appearance in theological and confessional treatments as a way of understanding the place of Old Testament law in the New Testament era. It is invoked e.g. in the Westminster Confession of Faith as such an interpretive principle. A good treatment of the theological usage of equity can be consulted here, but, there as typically, the Roman-legal background of the concept is only hinted at, if mentioned at all. To fill this void I offer the following considerations:

  1. Sohm’s historical outline shows how Roman law provided the basis for the doctrine of equity, upon which all further development proceeded. The Romans developed the idea of universally valid legal principles, by a process of inference and comparison at the level of court practice. Equity developed in tandem with the notion of a universal law of nations — ius gentium or ius commune.
  2. Stahl describes the achievement of the Romans as having discovered the principle of “the nature of the case,” i.e., the discovery of a framework for classifying the various cases and delineating the characteristics (Private Law, pp. 194ff.). But this also points up the shortcomings of the Roman achievement. It is restricted to practice and insufficiently informed by higher principles. Donald Kelley (The Human Measure: Social Thought in the Western Legal Tradition, ch. 9) describes how canon law developed a more Christianized concept of equity. In fact, he argues that canon law functioned as a sort of equity overarching the particular legal systems of the West. Berman (Law and Revolution, ch. 6) points up the many ways that canon law influenced secular legislation in this manner.
  3. The concept of equity also became attached to Roman law generally, in the form of Ius Commune (common law). Sohm already hinted at this functionality when he showed how equity developed together with the concept of ius gentium (law of nations), a common overarching law (my book A Common Law also discusses this). This understanding of the role of Roman law in the West was developed most famously by one of the premier legal historians of the last century, Francesco Calasso. Hitherto scholars viewed the Roman law as a kind of residual positive law, valid directly in the absence of relevant local or national law. But Calasso showed that it functioned as a form of equity in the lawmaking and interpreting process. Manlio Bellomo was a disciple of Calasso’s and put forward the thesis in The Common Legal Past of Europe 1000-1800, which I highly recommend.
  4. England developed a separate jurisdiction of equity alongside the common law courts, in the Court of Chancery. One good place to read about this is C.K. Allen’s Law in the Making, pp. 382ff. Of course, the Court of Chancery and its dilatory working was the target of Dickens’ venom in Bleak House.
  5. Stahl cautioned against the application of equity in adjudication. He argued that equity cannot be used as a criterion for invalidating standing law. It can only be used where law is unsettled or where it is specifically attributed a role in the legal system. “The essence of justice is to maintain a given order, law and right inviolably intact, while the essence of equity is precisely disregarding all prior existing order, all prior conferred law and right, simply to restore the equality of advantages and disadvantages (aequum) among those concerned…. In terms of its deeper root, equity rests partly on the original equal entitlement of men and partly on the equal love for all, which yields an equal standard everywhere where no special law, right, or right-founding act effects a preference. In this root, equity is reunited with justice, it consisting merely in disregarding those intervening grounds. A decision in accordance with equity is therefore in order where such facts grounding a specific inviolable right are truly lacking, e.g., in the settling of confused boundaries, while in the contrary case it is a censurable violation of justice” (Principles of Law, pp. 126ff.).
  6. As an example of jurisprudential treatment of the concept in the 17th century, Althusius wrote “Æquitas contra stricto juri opposita” [equity is contrary to strict justice] and defined it as a principle for interpreting standing law (discussed in the chapter “De naturali juris interpretatio” or “on interpretation of/from natural law).  See the Dicaelogicae, pp. 48f.

All of these Roman-legal considerations in one way or another informed the concept of equity as understood in the mid-17th century, and should be taken into consideration as background for the theological discussions and treatments invoking the topic, especially in view of the fact that many leading theologians and intellectuals were trained in Roman law (e.g., Calvin, Beza, Hotman, De Mornay, Althusius, Rutherford).

Sources for further investigation

Bellomo, Manlio. The Common Legal Past of Europe, 1000–1800. Trans. Lydia G. Cochrane. Washington, D.C.: The Catholic University of America Press, 1995.

Buckland, W. W., Arnold D. McNair and F. H. Lawson. Roman Law and Common Law: A Comparison in Outline. Cambridge: Cambridge University Press, 1965 [1936].

Caenegem, R. C. van. An Historical Introduction to Private Law. Trans. D. E. L. Johnston. Cambridge: Cambridge University Press, 1992.

Dooyeweerd, Herman. New Critique of Theoretical Thought. 3 vols. Amsterdam and Philadelphia: H.J. Paris and the Presbyterian & Reformed Pub. Co., 1953–1958.

—. Roots of Western culture: pagan, secular, and Christian options. Toronto: Wedge Publishing Foundation, 1979.

Dooyeweerd, Herman. “The Relationship between Individual and Community in the Roman and Germanic Conceptions of Property.” Time, Law, and History: Selected Essays: The Collected Works of Herman Dooyeweerd, Series B, Volume 14. Grand Rapids: Paideia Press, 2017. 337–390.

Kelley, Donald R. The Human Measure: Social Thought in the Western Legal Tradition. Cambridge, MA: Harvard University Press, 1990.

Nicholas, Barry. An Introduction to Roman Law. Oxford: At the Clarendon Press, 1962.

Savigny, Friedrich Carl von. System of the Modern Roman Law, Vol. I. Trans. William Holloway. Madras: J. Higginbotham, 1867.

Sohm, Rudolph. The Institutes of Roman Law. Trans. James Crawford Ledlie. Oxford: At the Clarendon Press, 1892.

Wieacker, Frans. A History of Private Law in Europe. Trans. Tony Weir. Oxford: Clarendon Press, 1995.


[1] Ruben Alvarado, A Common Law: The Law of Nations and Western Civilization, 2nd edition (Aalten: WordBridge, 2019).

[2] Charles Howard McIlwain, Constitutionalism: Ancient and Modern, esp. ch. III.

[3] Though still making use of the imagery of a literal Roman Empire, Dante anticipated the empire’s transformation into an ideal community of Christian nations as a single civilization: see his De Monarchia.

[4] Wolfgang Kunkel, Römische Rechtsgeschichte [The History of Roman Law], § 5.1.

[5] Kunkel, § 5.2.

[6] Gaius, Institutes, § 1.1. Quoted in Justinian’s Institutes, p. 37.

[7] J. P. Canning, “Law, sovereignty and corporation theory, 1300–1450”, in J. H. Burns (editor), The Cambridge History of Medieval Political Thought c. 350–c. 1450, p. 471.

[8] Canning, “Law, sovereignty and corporation theory,” p. 473.

[9] Ullmann, A History of Political Thought, pp. 216–217.

[10] Josef Bohatec, Calvins Lehre von Staat und Kirche, p. 43.

[11] Bohatec, Calvins Lehre, p. 43.

[12] Bohatec, Calvins Lehre, p. 32.

[13] For the importance of Roman law as Western theoretical paradigm, see the work of Donald R. Kelley. A good place to start – in his case as well – is the Variorum Reprints edition devoted to his work: History, Law and the Human Sciences: Medieval and Renaissance Perspectives (London: 1984).

[14] For more on the Common Law Mind, see J.G.A. Pocock, The Ancient Constitution and the Feudal Law: A Study of English Historical Thought in the Seventeenth Century (Cambridge, England: Cambridge University Press, 1987 [1957]).

[15] Donald R. Kelley, “History, English Law and the Renaissance,” in History, Law and the Human Sciences, XI-37.

[16] Charles Howard McIlwain, Constitutionalism: Ancient & Modern (Ithaca, NY: Great Seal Books, 1958 [1940]), p. 57.