Published in The Jurists’ Philosophy of Law from Rome to the Seventeenth Century, edd. Andrea Padovani and Peter G. Stein (A Treatise of Legal Philosophy and General Jurisprudence 7; Dordrecht: Springer, 2007) 157-211

Politics in Western Jurisprudence

Kenneth Pennington

In his work Politica methodice digesta that he published in 1603 Johannes Althusius defined politics as the “art of associating (consociandi) men for the purpose of establishing, cultivating, and conserving social life among them.” Althusius was an early modern German jurist who firmly believed that human social institutions were and should be regulated by law. “Common law (lex communis), which is unchanging, indicates that in every association . . . some persons are rulers (heads, overseers, prefects) or superiors, others are subjects or inferiors. For all government is held together by imperium and subjection.” “Local laws (leges propriae) are those enactments by which local associations are ruled.” Althusius did not think of politics as being primarily the art of conflict but the art of living together. Law provided the foundation of a community’s social structure.

            Althusius lived in the waning years of the Ius commune, the common law that was taught in all of Europe’s law schools until the Protestant Reformation. It was not a set of statutes. Rather it was a set of norms and a jurisprudence that was based on ancient Roman, canon, and feudal law. It provided a rich source of principles for all European jurists. Although he was a Protestant, Althusius drew heavily upon legal traditions and sources of Pre-Reformation Europe. His Politics is studded with references to Hostiensis (Henricus de Segusio), Panormitanus, (Nicolaus de Tudeschis), Bartolus of Sassoferrato, Baldus de Ubaldis and many others. He summarized five centuries of jurisprudence in the Ius commune that dealt with all aspects of human concourse.

            The Ius commune was born in the late eleventh century. In the early Middle Ages, Europe was a land without jurists. With the establishment of law schools, first at Bologna and then in other Italian, French and Spanish cities, jurists began to discuss issues that may be broadly defined as political. In the modern world we primarily think of politics as a continuing struggle between parties with differing ideological and economic beliefs. From the thirteenth to fifteenth the Italian city states did have competing, organized parties striving for control of political institutions of their communities. The rest of Europe, for the most part, did not. Medieval jurists dealt with political matters in two ways. They analyzed and developed legal rules for the governance of political institutions from the office of the prince to the corporate governance of cities, secular and ecclesiastical corporations (guilds, cathedral chapters, monasteries), and representative assemblies. The jurists were also called upon to render opinions on legal questions that arose from political conflicts in medieval society. They became experts who were asked to solve problems, answer questions, and advise princes. Law was established as an important branch of learning, and jurists became an indispensable class in the political life of European society.

1. The Jurisprudence of Sovereignty in the Twelfth and Thirteenth Centuries

            Law became important in political debates of the second half of the eleventh century. The conflict between Pope Gregory VII (1073-1085) and the German Emperor Henry IV (1056-1106) generated a mountain of literature. One of the first signs that law would play a role in political disputes was a treatise written by a certain Petrus Crassus. He used Roman and canon law to defend Henry IV and cited Justinian’s Institutes to establish the principle that kingdoms cannot be ruled without laws.

            As law became important in politics and in all other parts of medieval society schools were established to teach it. Stories circulated about how the teaching of law originated. Not surprising some of these tales credited rulers with encouraging the teaching of Roman law. One of the most intriguing is a report by a German chronicler, Burchard of Biberach, that Matilda, Countess of Tuscany, petitioned Irnerius to teach the books of Justinian’s compilation. Whether the story is true or not it reflects an assumption of the early twelfth century that rulers were interested in fostering the study of ancient Roman law and that the knowledge of law would enhance a ruler’s authority. In any case Irnerius was a major figure of the early twelfth century who taught law in Bologna, advised the Emperor Henry V (1106-1125), and served as a judge in Tuscany. Legal historians generally credit him and an even more shadowy figure, Pepo, for establishing Roman law as a field of study in Bologna.

            The reign of the German emperor Frederick I Barbarossa (1152-1190) marked the beginning of the jurists' using their recondite knowledge in the service of the prince. Frederick recognized the importance of jurists and protected the Law School at Bologna with an imperial decree, the Authentica Habita (1155), that granted the students at Bologna special privileges. Three years later at an imperial Diet in Roncaglia (near Piacenza) Frederick opened the assembly with a with an oration that contained a remarkable number of references to texts of the libri legales, the textbooks used at Bologna. The emperor tacitly cited Justinian’s Digest, Code, and Institutes to justify his rule. The texts of the libri legales legitimized his authority but also protected the rights and liberties of his subjects. When he proposed new laws, as he did at Roncaglia, he promulgated them but, he said, the people confirmed them by accepting them through customary usage. He proclaimed that laws must be just, possible, necessary, useful, and suited to the time and place. He concluded by pointing out that one may not judge laws after they have been established. Rather one must judge according to the laws. All of these points were taken from the libri legales.

            Frederick’s speech at Roncaglia was not an isolated example of the importance of law for imperial rhetoric and policy. Godfrey of Viterbo wrote a poem that exalted Frederick’s legislative authority and employed the standard metaphors of the new jurisprudence to describe the imperial office: the emperor was living law and could promulgate, derogate or abrogate law.

            Frederick promulgated new laws that treated the emperor’s rights and prerogatives in Italy at Roncaglia. An Italian chronicler wrote that Frederick summoned law professors from Bologna to advise him on his imperial rights that were due to him. One of the laws is particularly instructive.

The prince possesses all jurisdiction and all coercive power. All judges ought to accept their administration from the prince. They should all swear the oath that is established by law.

This law was entirely based on principles of Roman law. Frederick did not know Latin and was not educated in law. He gathered men around him who were experts of the libri legales, the new legal science. European princes would follow Frederick’s lead for the next 700 years. They gave jurists positions of power and authority in their curiae and used them as trusted and advisors. The laws that were promulgated at Roncaglia began a long tradition of medieval jurists’ contributing to the formation of a jurisprudence of sovereignty.

            It is instructive to compare the promulgation of King Henry II (1154-1189) of England’s Constitutions at Clarendon (1164) to Frederick’s legislative work at Roncaglia. Henry made no claim to have the authority to legislate. He gathered his barons and bishops together to “recognize” royal liberties and prerogatives. A “recognition” of law was the same term used to discover the facts of a case by jurors in early English writs. In England law was not a manifestation of royal prerogative; it was a fact that could be discovered by examining the customs of the realm. There is no trace of the new jurisprudence of monarchical authority in the rhetoric that justified the Constitutions. The English kingdom would only begin to be influenced by the legal theories of sovereignty of the Ius commune in mid-thirteenth century when the author called Bracton attempted to describe the prerogatives of the king using some of the same texts and language that were used to exalt Frederick Barbarossa’s authority at the Diet of Roncaglia.

            A story that circulated among the jurists illustrates the authority that jurists began to exercise in medieval society. The setting of the story was the Diet of Roncaglia. It may or may not be true. The protagonists were two of the four great doctors and teachers of Bologna, Bulgarus and Martinus. Frederick had summoned these experts to Bologna to advise him. While riding with them on horseback on day, Frederick asked them whether according to law he was the Lord of the World (dominus mundi). The idea of the emperor's being the “dominus mundi” was probably inspired by a passage in the Justinian’s Digest. In a passage taken from a commentary on the Rhodian Law of the Sea, the Emperor Antonius declared that he was the “Master of the World” (tou kosmou kurios). Another text of Roman law became closely associated with the imperial title in the minds of the jurists. In a law that was included in his Code, Bene a Zenone, Justinian did not claim the title, Lord of the World, but he did assert that the emperor could be understood to own all things. If the emperor owned all things, it was a short step for the jurists to conclude that the emperor was, indeed, the Lord of the World.

            Frederick must have heard from people in his court that the emperor had these grand titles. He asked the jurists what authority and prerogatives such titles bestowed upon the imperial office. “Am I legally the Lord of the World,” he asked. The tradition reported that Bulgarus declared that he was not the lord over private property. Martinus responded that he was, in fact, Lord of the World. Frederick rewarded Martinus’ sycophantic answer with a gift of a horse.

            In the second half of the twelfth century the jurists who glossed Justinian’s codification dealt with these texts and others that touched upon the emperor’s prerogatives. They concluded that the prince did not have jurisdiction over his subjects private property under normal circumstances. Rights to private property were protected by natural law. One point should be emphasized. When Frederick asked whether he was Lord of the World, no jurist interpreted his question as asking whether other kings were subject to him. That question did not interest them. It would be left to Pope Innocent III to broach that question at the beginning of the thirteenth century. The twelfth-century jurists focused on the emperor's authority to take the rights of his subject away and his prerogative to abrogate law arbitrarily. In other words they were interested in the relationship of the prince to the law.

            The Roman law libri legales gave the medieval jurists very fragmented texts upon which they could construct a theory of princely authority and of the prince’s relationship to the law. There is little in the Digest on a theory of law. A text in the Digest from the Roman jurist Gaius stated that natural reason established law that is observed among all human beings. It is call the Ius gentium or law of peoples. This law and the customs and laws of individual cities (civitates) constituted the laws under which human beings lived. The libri also contained some definitions of terms at the beginning of the Digest. The medieval jurist who began to study and comment upon ancient Roman law did not, however, have a coherent set of texts upon which they could create a jurisprudence that treated the nature of law. That task was taken up by Gratian who began to teach canon law at Bologna in the early twelfth century.

            When Gratian began teaching at Bologna, Irnerius was teaching Roman law at about the same time. Until recently the only secure fact that we knew about Gratian was that he compiled a collection of canons that later jurists called the Concordia discordantium canonum. This cumbersome title was later shortened to the Decretum. It very quickly became the most important canonical collection of the twelfth century and later became the foundation stone of the entire canonical jurisprudential tradition. It was not replaced as a handbook of canon law until the Codex iuris canonici of 1917 was promulgated.

            Since the work of Anders Winroth in 1996 we have learned much more about Gratian. Winroth discovered four manuscripts of Gratian’s collection that predated the vulgate text of the Decretum. Since then another manuscript of this early recension has been discovered in the monastic library of St. Gall, Switzerland. Although all five manuscripts must be studied in detail before we fully understand their significance, some conclusions can already be made. The first recensions of Gratian’s work were much shorter than the last recension. The differences between the recensions mean that Gratian must have been teaching at Bologna for a significant amount of time before he produced his first text that circulated. There was a significant period of time between when he began teaching and the final version of the Decretum. Most evidence now points to Gratian’s having begun his teaching in the 1120's. He continuously revised his text until the late 1130's or early 1140's. In spite of its defects — organization was its primary flaw — it immediately replaced all earlier collections of canon law in the schools.

            Gratian became the “Father of Canon Law” because the last recension of his collection was encyclopedic and because with his “case method” he provided a superb tool for teaching. His vulgate version of the Decretum was a comprehensive survey of the entire tradition of canon law.

           Gratian introduced jurisprudence into canonical thought. His first innovation was to insert his voice into his collection to mingle with those of the Fathers of Nicaea, St. Augustine, and the popes of the first millennium. He did this with dicta in which he discussed the texts in his collection. He pointed to conflicts within the texts and proposed solutions. His dicta made the Decretum ideal for teaching, and the Decretum became the basic text of canon law used in the law schools of Europe for the next five centuries.

            In addition to the novelty of his dicta, Gratian created a collection of canon law that was organized differently than any previous collection. In his earliest version of the text, Gratian focused on 33 cases (causae). In each case he formulated a problem with a series of questions. He then would answer each question by providing the texts of canons that pertained to it. When the text of the canon did not answer the question without interpretation or when two canons seemed in conflict, Gratian provided a solution in his dicta. Gratian’s hypothetical cases were effective teaching tools that were ideally suited to the classroom. Gratian was the first teacher to use cases to teach law.

            Perhaps the most important parts of Gratian’s work for the beginnings of European jurisprudence were the first twenty distinctions of the 101 distinctions (distinctiones) in the first section of his Decretum that he added to his original text. In these twenty distinctiones he treated the nature of law in all its complexity. Gratian must have realized that he could not teach law by looking only at cases and questions of fact. He had to make his students understand the sources of law. As I pointed out above, the libri legales did not discuss the relationship between the different types of law. Gratian did that in his first twenty distinctions. These twenty distinctions stimulated later canonists to reflect upon law and its sources.

            Gratian began Distinction one with the sentence: “The human race is ruled by two things, namely, natural law and usages” (Humanum genus duobus regitur naturali videlicet iure et moribus). The canonists grappled with the concept of natural law and with its place in jurisprudence for centuries. Their struggle resulted in an extraordinary rich jurisprudence on natural law and reflections on its relationship to canon and secular law. Brian Tierney has noted that “natural law <did not> constitute a significant limitation on the legislative competence” of the prince. It was also not “a kind of detailed pattern of legislation laid up in heaven.” Rather, natural law provided a moral basis for deciding whether a given enactment was a good and just law. It was a set of norms that evolved in European jurisprudence through a long gestation in the arguments of the jurists. In some cases, the jurists found justifications in sacred scripture for their arguments about which norms were based on natural law. In others, they could discover no precedents in sacred scripture. Instead they relied on norms that had evolved in the Ius commune. These norms conformed to reason, reason so compelling that they expressed eternal truths. We shall see that the jurists used norms and principles that they defined as natural law to limit the authority and prerogatives of the prince.

            Gratian concluded that natural law dictated that “Each person is commanded to do to others what he wants done to himself,” connecting natural law with the biblical injunction to do unto others what you would have them do unto you (Matthew 7.12). By defining natural law as the duty to treat other human beings with care and dignity, Gratian encouraged jurists to reflect upon a central values of natural law: the rendering of justice and the administering of equity in the legal system. The inspiration for Gratian's dictum was two texts in Justinian's Digest (Dig. 1.1.9 and 1.1.10).  Most of the texts that Gratian used were taken from the Etymologiae of Isidore of Seville ©. 560-636). Isidore combined the various traditions of natural law that had circulated in the ancient world. He defined it as being the law common to all nations that was established by the instigation (instinctus) of nature, not by human legislation. Examples of natural law were marriage and the procreation of children, “one liberty of all human beings (una libertas omnium),” and the acquisition of property taken from the heavens, earth, and sea. Natural law was, as the Roman jurists had earlier concluded, natural reason. To define the contents of natural law Gratian placed Isidore’s definition of natural law on the first page of his Decretum (D.1 c.7). Together with the texts of Roman law in Justinian’s compilation, Gratian’s Decretum became one of the standard introductory texts for the study of law (the Ius commune) in European law schools, and Isidore’s definition became one of the most important starting points for all medieval discussions of natural law.

            Gratian also discussed the various types of human law: unwritten custom, civil law, the law of a city or of a people, including definitions taken from Roman law. Law was a hierarchy. Under Gratian’s schema laws were not simply reflections of different usages in various communities. All law had to be evaluated according to standards that transcended human institutions. Law was also intimately connected to people. The prince could not exclude his subjects from being an central source of law. The people could not only make law, they could approve it. Gratian ended his treatment of legislation by defining how law became valid: “Laws are established through promulgation and validated when they are approved by the acceptance of the people.” Remarkably, Frederick Barbarossa used these very words when he described his conception of his legislative authority at Roncaglia.

            Gratian and Frederick marked the beginning, not the end, of the jurists' contemplation of the role of the prince in making law. The jurists read the texts in the libri legales that described the emperor’s supreme legislative authority and were uncertain how to reconcile the authority of the medieval prince with the powerful tradition of customary law. Customary law had dominated Europe for centuries. Almost all local legal systems were based on customary law in the twelfth century. Frederick Barbarossa’s legislation at Roncaglia is one of the few examples that we have in the twelfth century of a monarch’s consciously exercising his authority to make new law.  The assizes of King Roger II of Sicily are another.

            The twelfth-century jurists did not agree about the relationship of custom to new legislation. Irnerius wrote that custom that was established by long usage should be preserved, particularly if it were not contrary to reason and did not contradict written law. He did not, however, think that custom could abrogate the decrees of the prince. “All power of making law has been transferred to the prince.” Other jurists argued that under certain circumstances, particularly with the tacit approval of the prince, custom could derogate, if not abrogate, law. A maxim began to circulate in legal circles that “custom was the best interpreter of law.”

            During the course of the twelfth century jurists focused much more on the power of the prince to make new law than on the right of the people to establish and be governed by their own customs. A few jurists noted that society needed new laws because change demanded them. By the end of the twelfth century canonists had created a new concept to describe the law promulgated by the prince or by governing institutions: positive law (ius positivum). The term remains a fundamental legal concept in our understanding of law.

            The change from a legal system that recognized custom as the primary source of law to one that gave primacy of place to positive law was a difficult one. Southern European societies made the transition more quickly and easily than did those of Northern Europe. The Italian city states were the first to codify their customs and revise those codifications regularly as their institutions and courts evolved. Pisa, for example, produced a code of its laws by the middle of the twelfth century.

            Gratian, Irnerius and the early jurists took most of their assumptions about law and it relationship to princely authority from Germanic customary law and feudal law. Customary law emphasized the contractual relationship between the people and the prince. Consequently for early jurists the prince had a sacred duty to defend the laws and customs of the land. The prince was bound by the law. They thought that law should be reasonable and just. Most importantly, the prince could not exercise his legislative authority arbitrarily.

            At the beginning of the thirteenth century the jurists developed new ways of looking at law. Until then jurist focused on the content of law when they decided whether a law was just or not. They presumed that law must be moral, ethical, equitable, and, most importantly, reasonable. As new theories of legislation emerged from the Ius commune, the jurists began to look at the sources of human law and the institutions that produced positive law. It was then that they discovered the will (voluntas) of the prince as a source of law. When they introduced the will of the prince into political discourse, they created a new political language that became “the basis of a new philosophy of law with Marsiglio <of Padua> and <much later with> Hobbes and was the original kernel of the recently dominant theory of legal positivism.” The jurists were the first to look upon the will of the prince as being a primary source of law. A canonist, Laurentius Hispanus (ca. 1190-1248) was the first jurist to peer into the body of the prince to find his will.

            Pope Innocent III (1198-1216) inspired Laurentius to reflect upon the will of the legislator. No pope or other medieval ruler shaped the political thought of the medieval jurists more than Innocent. In his decretals the pope exalted papal political power. Innocent emphasized the pope’s fullness of power (plenitudo potestatis) within the Church. Although the term was coined in the early Church, Innocent found it particularly useful for describing his authority. During the thirteenth and fourteenth centuries, secular rulers adopted papal terminology to describe their power and authority.

            Innocent issued a decretal letter, Quanto personam, in 1198 in which he made an unprecedented pronouncement on the roots of papal authority. He claimed that the pope exercised divine authority when he granted a bishop the right to leave his church.

God, not man, separates a bishop from his church because the Roman pontiff dissolves the bond between them by divine rather than by human authority, carefully considering the need and usefulness of each translation. The pope has this authority because he does not exercise the office of man, but that of the true God on earth.

Laurentius quickly understood the implications of Innocent’s rhetoric. He believed that royal and papal authority was divinely ordained. That was a widely-held idea in late antique, medieval, and early modern political thought. Innocent, however, took this commonplace of medieval political thought and took it a significant step further. He asserted that the pope’s authority rested upon divine authority and also that the pope shared in God’s authority. That was a significant innovation. For the future it meant that the pope could exercise power that had hitherto been reserved only to God. Areas of law that had earlier been defined as based on divine law — marriage and vows especially — could now be subject to papal authority. If the pope shared authority and power with God, he could abrogate or derogate divine law that had been formerly beyond his jurisdiction. When Laurentius commented upon Quanto personam he defined a ruler’s legislative authority in a novel and unprecedented way:

Hence the pope is said to have a divine will . . . O, how great is the power of the prince; he changes the nature of things by applying the essences of one thing to another . . . he can make iniquity from justice by correcting any canon or law, for in these things his will is held to be reason (pro ratione voluntas) . . . And there is no one in this world who would say to him, “Why do you do this?” . . . He is held, nevertheless, to shape this power to the public good.

No jurist had ever made the claim that the prince could make laws that were unreasonable and unjust. The jurists always agreed that laws should be just and reasonable. Laurentius, however, asserted that reason was not the only standard by which law should be judged. The will of the prince and his will alone could be considered a source of human law. Earlier jurists had never distinguished clearly between the content of law and the source of law. Laurentius was the first jurist in European jurisprudence to argue that the content of law had no necessary connection to its source. It had been a doctrine of faith among the jurists who commented on Gratian’s tract De legibus that laws that were not reasonable were null and void. Laurentius, however, argued that the will of the prince must be supreme. He did not, however, argue that the prince could act arbitrarily. Later jurists did not use the maxim that he cited, “Pro ratione voluntas” (taken from Juvenal’s Satires) as a justification for tyranny.

            Frederick Barbarossa’s jurists who discussed the authority of the emperor in the twelfth century had a different and more primitive view of monarchical authority. When they called the prince the “Lord of the World” and declared that he was “legibus solutus” (not bound by the laws), they focused on his status. The prince was sovereign, he was superior to the law, but he had to submit himself to the law. They did not explore the source of law or of the prince’s authority or the relationship of the prince and the law.

            The reason for their reluctance to confront the issue of the relationship of the prince and the law was primarily because in the twelfth century the prince was not the only or even the main source of law in society. Only in the thirteenth century when princes began to legislate regularly did the jurists begin to think about the source the prince’s authority and to develop new definitions of the prince’s power.

            Henricus de Segusio, or Hostiensis, († 1271) was one of the most important and influential jurists of the thirteenth century. His career took him to Paris, London, and Rome. He wrote the most extensive commentary on canon law produced by any jurist in the thirteenth century. His work is characterized by a deep understanding of the political world, secular and ecclesiastical, and a profound interest in the language of political power and authority.

            Hostiensis was sensitive to legal questions that touched the structure of institutions. He developed a jurisprudence that described the power of secular and ecclesiastical princes in remarkably new ways. More than any earlier jurist he delved into the meaning of the terms that the jurists been accustomed to use when they described power and authority in medieval society. He extensively analyzed the traditional terminology. He explored the term “Plenitudo potestatis” (fullness of power) that had long been used to describe the power of the pope and that was beginning to be used to describe the authority of the secular prince in minute and careful detail.

            Like Laurentius Hispanus, Hostiensis was inspired by Pope Innocent III. Even more than Laurentius he emphasized the divine foundations of papal power. He decorated Innocent’s claims in Quanto personam with extravagant rhetoric. While commenting on Innocent’s decretal letters he wrote that all political authority comes from God. All princes exercised their authority by divine mandate. The pope, he asserted, had a singular status. Hostiensis based his commentary on Laurentius’ but greatly enhanced the pope’s power. Whatever the pope does, he wrote, he acts on God’s authority. The pope is the vicar of God. The curia of the pope in Rome was God’s curia. Whatever the pope does is licit as long as he does not err in the faith. Whenever he acts “de iure” he almost always acts as God.

            The pope exercised divine authority and presided over a consistory that reached from heaven to earth. Pope Innocent III might have thoroughly relished Hostiensis rhetoric. One inexorable conclusion that one might draw from Hostiensis commentary is that if pope’s authority is divine, then his law must also be divine. This logical conclusion did not escape Hostiensis. Divine law is the “Ars artium” (Science of sciences) that comprises human and canon law. Roman law is divine because the emperors created the rules of procedure by divine inspiration. The emperor is the living law (lex animata) whom the Lord has given to men and to whom He has subjected the law. Canon law was also divine. Theology was the head of the Church, canon law the hand, and Roman law was the feet. Sometimes the hand of the Church leads the head; sometimes the feet. Hostiensis did not create a new jurisprudence of law but outfitted traditional definitions with remarkable metaphors.

            In one respect Hostiensis did break with previous jurisprudence. He insisted that canon law was a part of divine law and that the pope, as vicar of God, promulgated laws that should be considered divine. A similar metaphor for the secular prince circulated in canon law. When princes issue laws, they are divinely promulgated through his mouth (leges divinitus per ora principum promulgatae). This is true, concluded Hostiensis, only indistinctly. Only the pope could promulgate law divinely. “The pope, not the emperor, is the general vicar of Christ.”

            Hostiensis’ most important and lasting contribution to the language of political thought was creating a new set of terms to describe sovereignty and the power of the prince. Ancient Roman jurisconsults introduced the jurists of the Ius commune to the basic language of sovereignty. The Roman jurisconsult Ulpian coined the most widely used definitions of the prince’s authority: “what pleases the prince has the force of law (quod principi placuit vigorem legem habet)” (Dig. 1.4.1) and “the prince is not bound by the law (princeps legibus solutus est)” (Dig. 1.3.31). Twelfth-century jurists used these two maxims to establish two principles: that the prince can legislate and that he can change law. The jurists also expressed the concept of legislative sovereignty with the maxim “an equal cannot have authority over an equal” (par in parem imperium non habet). This maxim expressed their conviction that a ruler could not bind his successor. No twelfth-century jurist permitted the prince to act or to legislate arbitrarily.

            Roman jurists called the emperor’s power to legislate, command, and judge “imperium” or “potestas.” Ulpian wrote that the Roman people had transferred “imperium” to him (Dig. 1.14.1). Most medieval jurists thought that the people’s bestowal of power on the prince could not be revoked. Borrowing from theologians’ terminology describing the power of God, Hostiensis gave the pope a glorified new definition of his authority. The pope and God both ruled by a “potestas absoluta" and "potestas ordinata.” Since Hostiensis thought that the pope promulgated law divinely he followed the logic of his theory and concluded that terminology describing God’s power should also apply to the pope. The pope was the first human being to wield divine power, but jurists soon bestowed “potestas absoluta” on secular princes.

            Like Laurentius before him Hostiensis blazed a new path for the jurisprudence of sovereignty. He separated legal thought from primitive Germanic ideas of kingship that law was custom and that the king was bound by the law. With his “potestas ordinata” the pope had the authority to exercise jurisdiction over positive law; “Potestas absoluta” enabled the pope to exercise extraordinary authority and jurisdiction. With this exalted power the pope could legislate in matters touching the law of marriage and vows, areas of the law that had been considered a part of divine law and outside papal jurisdiction.

            “Potestas absoluta et ordinata” played a very important role in the future. Later jurists defined the prince’s power with these terms and sometimes concluded that the prince could take the rights of subjects away when he exercised his absolute power. In combination with Laurentius’ “pro ratione voluntas” the jurist used “potestas absoluta” to create more a sophisticated jurisprudence of sovereignty. The prince was the source of law. He was not always limited by reason or morality. Under some conditions the prince could promulgate laws that were contrary to reason. He could sometimes act contrary to the precepts of justice. The jurists justified these aberrations of political behavior by citing two other norms: the common good of society and great necessity. By the later Middle Ages the jurists could defend the prince who acted contrary to law, custom, and who violated individual private rights. Hostiensis laid the foundations for later jurists to embrace an absolutism that ignored the traditional rights of subjects.

            Along side this development, however, medieval “constitutionalism” remained an important strand of thought in medieval jurisprudence. Many jurists were reluctant to adopt a theory of absolutism that did not limit the prince’s power. Their first line of defense against arbitrary power was the rights of subjects. From early in the twelfth century jurists asserted that property rights were founded on precepts of natural law or the “ius gentium.” Further, the prince did not have the right to alienate his lands. When the jurists argued that property rights were grounded in natural law they could claim that the prince could not violate those rights since he had no jurisdiction or sovereignty over natural law. It was a higher law that transcended human positive law.

            The alienation of property was a key issue for the jurists. From the late twelfth century they realized that rights that attached to the office of the prince and not to his person be