Origins of the concept of sovereignty in international law in the Middle Ages

(Originally included - in Dutch - in: Proceedings of the IX Dutch-Belgian Legal History Conference

– Concerning Feenstra – Saturday, November 2, 1985; Leiden, pp. 29-46. Translated by Neale Williams.)

THE ORIGINS OF THE CONCEPT OF

SOVEREIGNTY OF INTERNATIONAL LAW IN THE MIDDLE AGES

By Ton Lenssen LL.M

When in 1983 the Council of State of the Kingdom of the Netherlands was asked for advice on the proposed agreement with the United States to deploy cruise missiles in the Netherlands, the Council felt compelled to define sovereignty. It did this as follows, ‘Sovereignty is empowered governmental authority, which in its relations with other states recognizes no authority above itself’ (Advisory Opinion, September 23, 1983).

From the perspective of legal history, this method of definition is very interesting. Simply by way of the fact that the Council of State did not consult a book on current constitutional law for its definition, choosing as one usually does: sovereignty is the supreme power. Or, as professors Burkens and Voorhoeve put it in the Dutch broadsheet NRC/Handelsblad of September 28, 1985: sovereignty is ‘simply the highest sovereign authority’. Indeed, these are meaningless terms. The formula that the Council of State adopted, however, was a rich combination of elements which have emerged in the course of the history of European constitutional and international law. Albeit with some difficulty one can recognize in the first part the concept of governmental authority which is derived from the definition of constitutional sovereignty given by Bodin in 1576 in Les six livres de la République. In the second part one finds a formula that was developed even earlier, namely in the thirteenth century, that of so-called sovereignty of international law.

This latter concept is what will be focussed on here: the authority which outwardly recognizes no higher than itself, i.e. qui superiorem non recognoscit. Although it is especially significant that the Council of State should refer at all to such a formula with a history, it is equally interesting to note that the formula which the Council avails itself of is not new, but dates back to the Middle Ages. The Council consequently shares a rather common sentiment found in the literature of international law. Here it is indeed proposed that sovereignty of international law can be defined as the authority of those who recognize no higher authority, and that this is a formula that already existed in the thirteenth century, so that one can speak of ‘the origins of the concept of sovereignty of international law in the Middle Ages’.

However, the history of the formula used to define sovereignty of international law is not the only history we need to look at. There is another history which needs looking at first, namely that of the debate about the history of this formula. This debate can be confidently traced back to the beginning of the twentieth century, partly due to two publications by Eduard Meijers, which were published by Robert Feenstra in Etudes de l'histoire du droit (vol. IV). This will be my starting point and I shall spend some time on it here. Primarily because I want to utilise for the history of international law, for which it was not originally written, what Meijers postulates, but also because it is an excellent source of material which itself is open to adaptation. At least that is my assumption for now.

If, at the beginning of the twentieth century, one talked about the independence of international law or sovereignty, one generally agreed with Bartolus of Sassoferrato. Whereas almost all jurists prior to Bartolus had learned that states and sovereigns which were actually independent, were nevertheless subject de iure to the authority of the emperor, Bartolus himself held the viewpoint, civitas superiorem de facto non recognoscens est sibi princeps: a state which actually recognizes no higher than itself, is its own sovereign; or, est populus liber: is a free people. With this formula Bartolus has become one of the most powerful propagators of the modern conception of sovereignty of international law. Ercole, in his study of 1915, L'origine francese di una nota formola Bartoliana, attempted to demonstrate that Bartolus’s notion was of French origin. According to him it had been Guilielmus Durantis, the first jurist schooled in Roman law, who declared his French king independent of the emperor. Durantis wrote in his Speculum iudiciale, ‘Rex Franciae princeps est in regno suo, ut pote in illo in temporalibus superiorem non recognoscat’. Meijers points out that in this Ercole is mistaken, as it had not been Durantis but rather the Burgundian Jean de Blanot, from whom Durantis had literally transcribed the formula in question. In Bologna in 1256 Jean de Blanot had published a Tractatus de actionibus and under the heading, de praejudiciali, per quam petitur vasallus, had written about a vassal who had followed his suzerain in his struggle against the king, ‘Baro ille qui insurgit contra Regem, videtur incidere in legem Jul. maiestatis ex illo capite quia videtur machinatus in mortem magistratus populi Romani, vel verius quod directo videtur fecisse contra principem, nam rex Franciae in regno suo princeps est, nam in temporalibus superiorem non recognoscit’. I have translated this as, ‘This baron, who rebels against the king, is expected to contravene the lex Julia majestatis by virtue of the fact that he is deigned to have plotted the death of a magistrate of the Roman people; or, stronger still, he is expected to have acted immediately against the sovereign, since the King of France is sovereign in his own kingdom, now that at least in secular affairs he acknowledges no higher than himself’. One can see what happens: in order to apply the lex Julia majestatis in the conflict between the King of France and a vassal of the Count of Toulouse, one contrives, as it were, that the King of France is the ‘princeps’ in the lex Julia majestatis, and that France is the ‘populus Romanus’. Although, and this is obviously the point, only the emperor was permitted to call himself ‘princeps’, and the emperor, that was of course the Holy Roman Emperor. By way of the fact that the King of France was now also calling himself ‘princeps’, he was doing what Azo had observed various sovereigns doing around 1200: ‘Item quilibet (rex) hodie videtur eandem potestatem habere in terra sua quam imperator’. Whether by this Azo had observed a fact or had simply formulated a standard, is not clear.

In later work, Ercole took Meijers’ rebuke to heart and no longer defended the reference of ‘origine francese’ in the nota formola Bartoliana to Durantis but made it instead to Blanot. However, in 1930, this thesis of the French origin of the Bartolist formula was attacked by Calasso in an article whose title speaks for itself: Origini italiane della formola ‘Rex in regno suo est imperator’. According to Calasso, the origin of the formula of which Bartolus avails himself should not be sought in France but rather in the Kingdom of Sicily. When Charles of Anjou became king there in 1266, he entrusted the jurist Marino da Caramanico with the compilation of the laws which Frederick II had promulgated for Sicily. It was not about the laws he had decreed as emperor, but rather those promulgated under the title of king. The question, of course, was how Frederick could justify this, seeing that ‘constitutiones’ could indeed only originate from the ‘princeps’, and Frederick was only ‘princeps’ as emperor of the Holy Roman Empire. Caramanico addresses this question in his Prooemium to the Liber constitutionum, where he says, ‘Sed in rege libero, qui nullius alterius potestati subiectus est, idem dicimus, scilicet ut rex possit condere legem (D. 49,15,7,1), qualis est rex Siciliae ...’ Ercole responds directly to this by pointing out that this Prooemium by Caramanico dates at the latest from 1282, while Blanot, whom he quotes incidentally from Meijers, wrote in 1256. Moreover, says Ercole, since there were close intellectual ties between France and the Kingdom of Naples to which Sicily belonged, especially in the time of Charles of Anjou, it is obvious that Caramanico was acquainted with the ideas of a French jurist who had written 25 years earlier.

Calasso, however, raises the debate to an entirely different level. He says that in the period of Blanot and Caramanico the problem in question was generally under discussion. It was not only these two glossators who had written about this. As early as 1202 we encounter Azo’s previously quoted text, and in 1208 we can identify a text by the canonist Alanus: ‘Et quod dictum est de imperatore dictum habeatur de quolibet rege vel principe qui nulli subest. Unusquisque enim tantum iuris habet in regno suo quantum imperator in Imperio’. And in the time of Blanot himself, around 1265, one finds in the Siete Partidas of Alfonso X of Castile: ‘Vicarios de Dios son los reyes cada uno en su regno puestos sobre las gentes para mantenerias en justicia et en verdad quanto en lo temporal bien asi como el emperador en su imperio’ (II, tit.1, l.5). Therefore, it is not actually about the date of origin of the formula in question, claims Calasso, but about something entirely different. Marino da Caramanico happens to have been the first to have formulated the rule of sovereignty of international law as a general principle and not merely as a claim to independence of a single, specific state. He gave the rule an objective character, reasoned it, justified and expanded it to a much greater degree than the incidental observations that other jurists had made.

One could say that Caramanico formulated ‘sovereignty of international law’ as a rule of international law, while the other jurists mentioned did nothing more than formulate the claim to a privilege for their country or sovereign. If I understand correctly, Calasso reasons this as follows: Caramanico believes that one can argue that a free king who is not subordinate to the authority of anyone else, holds the same jurisdiction to make laws as the emperor has according to Roman law; that is a general rule, which in turn is then applied to an actual case, namely the King of Sicily. With this Caramanico has not limited himself to the individual case of the King of Sicily, but instead has reasoned from a general principle which he also explicitly puts into words.

Perhaps it could have been left at that. However, in 1951 Sergio Mochi Onory published his book Fonti canonistiche dell'idea moderna dello stato, in which he turns to the canonists of the twelfth and early-thirteenth centuries for the source of the modern idea of sovereignty. According to him, the civilists of the period only possessed a vague and complex idea of sovereignty, while the canonists had already devised constructs and new theories. He discusses two subjects in particular, between which, it is true to say, a certain link exists, although remaining clearly distinct from each other: the division of spiritual and secular authority between the emperor and the pope, and the legal relationship between the emperor and the kings of other Western states, such as France, England and Spain.

With regard to the first subject, it should be noted that in the second half of the twelfth century there was an accentuation of a body of thought among the canonists, which had already begun at the start of the century, and which argues that the authority of the pope is above that of the emperor. The premise still remained the division iurisdictio spiritualis and iurisdictio temporalis, but the possibility of the pope’s indirect intervention as spiritual head in secular jurisdiction increased: in addition to the consecration, the coronation and the power of excommunication, the pope had the authority to intervene in a succession to the throne when the electoral nobility did not want to choose, or when someone unbefitting was chosen, to depose a king, to be petitioned during an emperor’s absence or in the event of refusal of jurisdiction, to adjudicate in the event of a breach of contract or treaty that had been ratified by an oath, to legitimise illegitimate children, and so forth.

With regard to the second issue, that of the legal relationship between the emperor and the kings of the other Western states, Mochi Onory applies the prevalent notion of the previous centuries that the emperor was the dominus orbis. What the pope was in the spiritual order, the emperor was in the secular. It had been the canonists who had applied a juristic basis to this supranational concept of the emperor’s rule. However, in the course of the twelfth century, the canonists increasingly abandoned this principle, due to the anti-imperial stance of the church and the political realism of the canonists. From the mid-twelfth century they begin to recognize the autonomy of certain political entities, such as the kingdoms, the provinces and even of cities (civitates and municipes). They assigned these political entities the authority to confer laws on themselves, and subsequently also to exercise the jurisdiction and imperium, as well as the same fiscal privileges Roman law granted the imperial treasury. The writers who particularly contributed to this had been the Italians Rufinus and Huguccio, the Frenchman Etienne de Tournay, and later the Englishmen Ricardus Anglicus and Alanus and the Spaniards Laurentius and Vincentius. Through an international collaboration the canonists had thus renewed the political theories and laid the foundations for the concept of sovereignty. This development resulted in the kingdoms of the West being considered as independent of the empire. Notwithstanding the fact that he acknowledged the subordination of the kings to the emperor, Huguccio already defended the view, ‘in regno suo idem est rex et imperator’. However, it was particularly Ricardus Anglicus and Alanus who had drawn the obvious conclusion from their premises. Ricardus says: ‘Set contra: Patet reges multos imperatori non subici. Videtur enim, quod sicut per violentiam essent subditi, quod violenter possint ad propriam redire libertatem... Item cum uterque tam imperator quam rex eadem auctoritate eadem consecratione, eodem crismate iungitur, unde ergo potestatis diversitas, ut XVI. q.I. § ecce sufficienter (C.16 q.1 d.p.c. 40)’. And Alanus postulated the proposition already cited above. In his decretal of 1201, Per venerabilem, Pope Innocent III reasserted: ‘quum rex ipse (i.e. the King of France) superiorem in temporalibus minime recognoscat’. While Laurentius en Johannes Galensis, in their gloss on the word ‘recognoscat’, had held firm in their belief that this only applied ‘de facto’, Vincentius Hispanus had already abandoned this notion around 1210 and had written that this was also ‘de iure’. And with this Mochi Onory concluded that the story was complete: as early as 1210 the canonists had achieved an accurate and proven result.

Mochi Onory’s result was in turn taken to task by Meijers in 1952. Meijers draws attention to, yet leaves further untreated, the question of whether the relationship between the jurisdiction of the emperor and that of the pope can be reasonably assessed without taking into consideration the contemporary publicistic and philosophical tracts. He restricts himself to what Mochi Onory has written about the development of canonistic theory concerning autonomy. Mochi Onory, he says, is being very negative about the civilists of the period, but has not read them. The canonists do nothing more on this subject than follow the ideas of the civilists. Meijers proves this with a number of examples which I can not go into now. His conclusion reads: the granting of autonomy to the city states and to the municipalities does not necessarily result in these political communities being declared independent of the empire. The glossators, for example, granted far greater authority to the civitates extra Imperium than to those who were located within the empire. Nevertheless, the canonists had granted the kingdoms of the West the same degree of autonomy that existed for the emperor at an earlier date than the civilists had done. On this issue Mochi Onory is absolutely right. However, this was not due to any dogmatic development in which the canonists indiscriminate of nationality had participated. It was merely as a result of the fact that during the first century of the revival of the study of Roman law, the civilists consisted solely of Italians, whereas the canonists belonged to different nationalities. The national sentiment was the determinant factor here. It is no coincidence that the first writers who declared that the independent kings had the same powers in their country as the emperor had in the empire, were English canonists (Ricardus Anglicus and Alanus), who in turn were followed by the Spaniards Laurentius and Vincentius, and by the Portuguese Johannes de Deo. As far as France is concerned, Meijers believes Blanot once again simply copies what the jurists of the French Crown had formulated for the rebellion of the Count of Toulouse. In actual practice, says Ercole, and Meijers agrees with him in this, the emperor had not been granted the powers of the ‘princeps’ in France, but rather the king had, and had so from the moment that Roman law had been exercised there, which was therefore from about 1200. And the French canonist Etienne de Tournay had already participated in the above-mentioned ‘international collaboration’ between the canonists of the twelfth century, to which he incidentally had nothing more to add than what Bulgarus had previously postulated, as Meijers has established.

When looked at as a whole, this literature can be characterized as the narrative of a journey back into history. From Bartolus one arrives at Durantis, from Durantis at Blanot, from Blanot at the practice since the moment at which Roman law held sway in France; from France one arrives at Italy, or at least at Sicily and at a new predicament; from the civilists one arrives at the canonists, and with them in the twelfth century. The question arises, just as in sport, whether there is a possibility to reach back even further? An answer to this can be given immediately: not if one continues to operate within the boundaries of Roman law, which only begins after all towards the end of the eleventh century.

This answer, however, places the whole of the previous narrative abruptly in an entirely different light. It is a narrative based on sources of a certain type: the writings of legists and canonists. In short it is a narrative that belongs to the history of jurisprudence. Does it also belong to the history of dogmatics of international law?

Until now we have mainly followed Meijers’ line of thought, which in the first instance was formulated in his article ‘Roman law in the Middle Ages’ (Le droit romain au moyen age). We could have also consulted Koschaker, who discusses the formula ‘rex in regno suo princeps est’ in his Europa und das römische Recht, where we would have encountered this narrative from a somewhat different perspective, namely as part of reception history. Parts of the narrative are also to be found in Ziegler’s Die römischen Grundlagen des europäischen Völkerrechts, but then from the perspective of the history of ideas, especially in defence of the polemical proposition that Roman law is at least one of the foundations underlying international law, and that there is a continuity between the time of Justinian and present-day international law. Given all this, the issue remains whether this material contributes at all to answering the question on the origins of the concept of sovereignty of international law from the perspective of the history of international law.

Of course it is certainly true to say that Meijers also places his paper within this perspective. As far as I can tell, his argument is also the most extensive and in-depth, although it still explicitly raises many questions which invite further research on the grounds he has established. In the literature pertaining to the history of international law this has certainly been ignored, for his views are rarely ever cited. So although we presently have to take leave of Meijers, we still have some way to go with him yet.

When he discusses Ercole, he points out that his premise contains a misconception. What needs explaining, he says, is not so much the way in which the idea of a sovereign state could have developed alongside the empire, but rather conversely how the idea of an empire could have been maintained at variance with the facts and the sentiment of the jurists. Meijers points out that Ercole himself stresses that from the time France came under Roman law, it was not the emperor but rather the king who was given the title of ‘princeps’. That is demonstrated, for example, in a decree dating from 1202, which was passed in the Curia Regis in which a jurist from Bologna served. Although here again with Meijers, notwithstanding an interesting and appropriate question, we have this fixation on Roman law. In answer to the question he himself has formulated, he adds nothing and does not return to it. And similarly with his remark that the relationship between the emperor and pope can not be studied without being acquainted with the writings of the publicists and philosophers of the time.

If it were indeed true that in France, as elsewehere, notwithstanding views which at least regarded the emperor de iure as the ‘princeps’, Roman law was also immediately applied in that other sense, in which the king was declared ‘princeps’, and if indeed that were conform the facts and the juristic sentiment, then one should actually conclude that this practice and juristic sentiment did not need Roman law at all, so that in existing international relations it was entirely inappropriate. And not only in the existing relations as they actually were, but also as they had been legally recognised, even though this legal recognition had not yet originated from jurists educated in Roman law. In other words there had long been a number of states, existing independent of each other and of the emperor, and this independence was experienced as a right. When the sources from the period before Bologna are consulted, one does not get the feeling that it was considered normal for one tribe or state simply to conquer and annex another, and moreover, that contact between these entities existed without standards.

When Meijers therefore formulates the problem in a way which requires examination of how it was possible that the emperorship could have persisted for so long, he argues that this emperorship existed as the true organisation of the medieval community. It appears to me that this idea of a medieval unit headed by the emperor, or alternatively headed by emperor and pope, forms, in addition to that of the history of Roman law, a second obstacle to viewing medieval international relations in the right perspective. It is not so much the question of how it was possible that the period of imperial rule could have survived so long that requires an answer, but rather how could imperial rule have existed at all? The simple answer to this was due to the effort of Charlemagne, and that it therefore existed by virtue of his power (and in turn became obsolete when it was powerless). However, from the perspective of international law, this does not answer the question. From this perspective the question is whether there was a rule or standard that provided the emperorship with any legal basis; an acknowledgement of imperial rule by the benefactors of international law or by those who were part of the respublica over which the emperor reigned. And for this it fell a good deal short.

Ernst Reibstein, in his Völkerrecht, also struggles with the concept of ‘Universalmonarchie’. On the issue of the origins of the concept of sovereignty of international law, Reibstein takes the position of Calasso, who attributes it to the Sicilian Caramanico. He does, however, resist an overly monistic conception of the Middle Ages and defends the existence of a plurality of states. In evidence he quotes an author who wrote ‘around 1070’, namely Adam of Bremen. Although Reibstein does not concern himself with the question on the role the history of the reception of Roman law plays in the research into the origins of the concept of sovereignty of international law, it is clear that an author ‘around 1070’ does probably provide some insight into how sovereignty of international law was viewed in the period previous to Bologna. In other words, Adam of Bremen is not only of importance in order to put the medieval monistic view into perspective, but also in order to determine the role of the reception of Roman law in the development of the concept of sovereignty of international law.

Only when the barriers of monism and reception history have been lifted, can the origins of the concept of sovereignty of international law be adequately addressed from within the perspective of the history of international law. With Reibstein one observes an extensive treatment of the development of international law ‘vom Altertum zum Mittelalter’, in which he first discusses Germanic international law, before going on to address the respublica Christiana. And also in the first part of the Histoire des relations internationales, written by Ganshoff and published in the 1950s by Renouvin and which deals with the Middle Ages, there are many interesting details to be found concerning international relations before the modern era.

It should be concluded that after the fall of the Roman Empire a constellation arose, which can safely be described as international, and that the relations in this constellation were subject to standards. For the period prior to Bologna this can easily be ascertained, for example, from the writings of Gregory of Tours, Einhard and Adam of Bremen, who are all quoted extensively by Reibstein. This was the international constellation that developed into the state system that arose at the end of the Middle Ages, and which is commonly regarded as the cradle of classical European international law. Before I go on to explain how I perceive this development, I need a short theoretical introduction.

J.P.A. Francois holds the view - which I share - that in order for international law to be established, two conditions have to be met: there has to be a plurality of states, or at least political communities, and this plurality has to express a certain spiritual unity, a sense of solidarity (Grondlijnen van het volkenrecht; 1967, p.2).

He is also of the opinion that these two conditions had been met in the world of the so-called barbarian kingdoms, which had developed on the territories of the Western Roman Empire after its fall. However, it should immediately be pointed out that although there might have existed a certain spiritual unity, that could not be said for a sense of solidarity. Therefore, this condition of spiritual unity or solidarity firstly needs to be formulated in terms of a problem before it can be applied.

The cohesion within the plurality, i.e. the unity of diversity, should not become so tight that it extinguishes the plurality, because then a new state would be created, be it in a federal, confederal or even a unitarian form, whereby what had first been international law, would now become constitutional law. An example of this process is the transition from an alliance into a federation or unitary state. Whereas the alliance is a structure of international law, the federation is constitutional. Conversely, the cohesion should not become so loose that it has no significance any more. Every rule of international law presupposes a foundation of relationship. International law’s existence therefore operates between the extremes of state anarchy or state individualism on the one hand, and on the other, that of constitutional law, but then of a new state in which the old plurality has been merged.

It is my premise that after the fall of the Roman Empire, state plurality experienced three movements towards greater solidarity, which at times were so strong that it seemed as if the plurality had dissolved and a unitary state had been created. This explains why many authors are of the opinion that medieval international law had not existed. According to these authors, the Middle Ages was simply the period of unity of the respublica Christiana under the leadership of pope and emperor which had existed somewhere between the Investiture Controversy and the emergence of the modern state system in the mid-fifteenth century. The three movements in question are, in chronological order, the papacy, the emperorship and the formation of the ius commune. I will now comment on these three movements individually.

The papacy began to play an independent role in political relations for the first time with Gregory the Great, pope from 590 to 604. Pope Leo I (440-461), had already claimed the so-called plenitudo potestatis which the Roman emperor was actually entitled to, but it was still to take more than a century before the papacy, to paraphrase Barraclough (The Medieval Papacy), truly emancipated itself from the emperorship. This is done on the basis of a theory which nowadays one refers to as political augustinism. In Pope Gregory's writings one can trace the gradual evolution of this emancipation and the emergence of this theory. If Gregory had initially felt greatly threatened by the degree of imperial power - he had been ambassador at the Byzantine court and had experienced the emperor’s power at first hand - at a later date he would state that God ‘entrusted to an earthly prince, on his conversion, that Church which He purchased by His own death, because, namely, He committed to his hand the great anxiety of preserving the peace of the faith’ (Moralium; Lib. XXXI, Cap. VI). With that, politics have been made subordinate to religion, christianised, and the foundation laid for medieval theocracy. This theory was further developed by later writers, including Isidore of Seville. It is nicely expressed by Jonas of Orléans in his De Institutione regia, written between 831 and 834: ‘All believers,’ he writes, ‘should realise that the universal Church is the Body of Christ and that his head is that same Christ, and that in this Church there are two principal figures: the priestly and the princely... And the priestly figure is insomuch the most significant that he must give account to God for the actions of the princes themselves... The princes’ duties consist of leading and governing God’s own people according to fairness and justice in order that peace and harmony are upheld’. It is clear that the sacerdotalis persona ‘supervises’, as we would express it today, the regalis persona. With Jonas of Orleans this sacerdotalis persona was certainly not only the pope - indeed for him it was more about the deposition of Louis the Pious by the French episcopacy - but certainly in the time of the Cluniac Reforms it becomes increasingly the pope who is the highest sacerdotalis persona. Nevertheless, up until the Investiture Controversy, the pope did regard himself above the emperor, but the emperor remained his enforcer, and up until the Investiture Controversy, it is common practice to attribute the emperorship with a supranational status.

This emperorship, the second movement towards greater unity in the Middle Ages, arises, as is well-known, in 800 with the coronation of Charlemagne. And since Charles had assumed a number of those titles that the Roman emperors had held, it could appear as if at this time the reception of a piece of Roman law, namely constitutional, had already taken place. However, as Koschaker rightly puts it, it was an emperorship without ‘Verbindung mit der klassischen Kultur der Römer und mit dem antiken imperium romanum’ (Europa und das römische Recht, p.37). What had actually been established was ‘ein imperium christianum oder ein fränkisch-christliches Imperium, mit geringerer oder stärkerer Betonung des germanischen Charakters dieses Reichs’ (idem. pp.22-23). Only in the period of the Salian and Hohenstaufen emperors did the spiritual link between the emperorship and imperial antiquity become much more profound. For example, one starts to find in the literature from the second half of the eleventh century onwards emperors being mentioned as the umpteenth successor to a Roman forebear. Adam of Bremen writes, ‘Heinrico imperatore, filio Conradi, qui a Caesare Augusto Romanorum imperatorum nonagesimus erat in solio’ (Gesta; Lib. III, Cap.1). Prior to this period is, ‘die Anknüpfung an das altrömische Imperium doch mehr äussere Form, Mittel zur Erreichung anderer Ziele...’ (Europa und das römische Recht, p.38). Therefore, not only was the emperorship, negatively speaking, not really Roman, it was, positively speaking, genuinely enough Christian and in spiritualibus subject to the authority of the pope. And up until the Investiture Controversy both powers generally spoke with the same voice, namely that of a universalist theocracy, through which they were confronted with a sometimes decisive and at other times hesitant plurality of political communities, which, conform the universalist concept, still had to be incorporated into this ‘Universalmonarchie’. This proved not to be universally possible. England always vehemently resisted inclusion in the empire; Sweden and Norway no less. Denmark similarly, but there it was less successful, owing to its unfavourable geographical situation for this. Southern Italy has also not always belonged to the empire, just like Spain, which at the time was still largely Arabic. Regarding the rest of the continent, it should be observed that the Carolingian Charles the Simple and the Saxon Henry the Fowler met in Bonn in 921 to conclude the treaty recognising one another as rulers of Western and Eastern Francia respectively. Wilhelm Grewe sees in this an example of institutional recognition of international law that formally constitutes Völkerrechtssubjekte. The emperorship was therefore politically and legally never anything else than a concept, a position. The emperor could sometimes serve as arbitrator, just like the pope, but that is what essentially every king could do.

Exactly to what degree the relationship is between the Investiture Controversy and the rise of Roman law is still unclear. Whatever the case may be, it suited the emperorship just fine that it could sacrifice its Christian principles for those of Roman law. Although the emperor had until now been by far the greatest defender of the faith, and his position had been strongly determined by his proximity to the pope, the consequences of the Investiture Controversy meant that that bond was severed. Papal policy was now directed more towards persuading the other independent kings, besides the emperor, of the fact that they were also responsible for defending the faith and that they should have Christian policies. With this the popes abandoned their original universalist or monistic policy. As a result of the fact that, other than the emperor, the independent kings were being acknowledged, it meant that in effect the emperor’s standing was being reduced, in that he became an equal of the other rulers.

And with this, political and legal life lost something which we believe was really nothing more than a concept, but as long as it existed, did play a genuine role. Indeed a new situation arises, which needs contemplating. The terms under which that contemplation takes place, are those belonging to Roman law stemming from Bologna. Initially it would appear that Roman law only speaks in favour of the emperor, seeing that this law only ever refers to there being a single ‘princeps’, who is entitled to decree constitutiones. However actual practice adapts itself quickly, and before long one sees that the independent rulers call themselves ‘in regno suo princeps’, while motioning deferentially to the pope, who supports all this, by adding that they are ‘princeps in temporalibus’.

The emergence of Roman law also certainly raised the notion of there being a unity, namely within the law. Indeed a certain ius commune also developed, as Helmut Coing describes in his Europäisches Privatrecht (1985; 1989). The unity resulting from this did not become a constitutional unity, but rather a private law and jurisprudential unity. When the independent sovereigns declared themselves ‘princeps’ in their own realms, they actually inhibited the constitutional unity which might have brought about the introduction of Roman constitutional law. For several centuries one was not entirely clear of the situation and up to and including Bartolus, the sovereigns were adjudged to be indeed de facto independent, but not de iure. By de iure one meant de iure romano. But of course that was not the only law that counted. This uncertainty resulted in only someone like Caramanico being capable of formulating a general rule.

I would like to make a further comment on this latter point. The criterion which Caramanico applied in order to determine whether a sovereign was independent or not, was the situation that it had to concern a ‘rex liber qui nullius alterius potestati subiectus est’. However, how can that situation ever actually occur, if there is only a single ‘potestas’ to which everyone is ‘subiectus’? In my opinion this statement also fails to provide any general criterion.

That genuine criterion only arrives with the teachings of Francisco de Vitoria in the sixteenth century. He too was busily occupied with the universalist theory of the emperorship, which at the time was held by Charles V. According to this theory, the newly discovered countries in America naturally fell under the emperor. Vitoria, on the other hand, defended the case that neither the emperor nor the pope was ‘dominus mundi’(Relectio de indis; II, 1 and 3; 1539). After the Flood the world is divided in ‘diversas provincias et regna’ or ‘nationes et regiones’ (idem. 1). And within these entities the ‘dominia et imperia’ are formed, which afterwards become transferred ‘vel iure haereditario vel iure belli vel alio tali titulo’, therefore at least by virtue of title (idem. 1). Prevailing between these entities is the right of the ‘naturalis societas et communicatio’ (idem. III, exordium). Indeed it was ‘numquam intentio gentium per illam divisionem tollere hominum invicem communicationem’ (idem. III, exordium). The barbarians of the New World, ‘quos Indos vulgo vocant’, are entitled to ‘dominium’ and ‘imperium’ because they ‘habent pro suo modo usum rationis’ (idem. I, 23). This is evident, says Vitoria, from the fact that they apply ‘aliquem ordinem’ to their affairs; and that indeed they have, ‘civitates quae ordine constant, ...matrimonia distincta, magistratus, dominos, leges, opificia, commutationes, quae omnia requirunt usum rationis’. Furthermore, they are not mistaken in affairs ‘quae aliis sunt evidentes’, and this is an ‘indicium usus rationis’. One can see here, therefore, a line of reasoning that actively searches for the rule that, when certain conditions have been met, a right to independence exists, the right which is sovereignty of international law.

It is only by way of such reasoning, I would argue, that this sovereignty can really be understood, and not simply by means of a generally successful, but largely unfounded formula. Moreover, Vitoria’s approach also successfully addresses at the same time the dual issues that the right to sovereignty of international law is based on the acknowledgement of the rationality of the constitutional and social organisation of a collective, and that international law is rooted in reason as the basis of interaction between nations.

I would like to word my conclusion in the following way. After the fall of the Roman Empire, a state plurality arose which could serve as the foundation for the development of international law, due in particular to the presence of a sense of independence, which might not have been strongly reflected upon, but nevertheless sufficiently well-developed to support a system of rules of international law. This plurality remained in existence despite the unifying efforts of the papacy, the emperorship and the reception of Roman law, which gave shape to the unmistakeable spiritual unity of the age. The final effort did lead to an increased degree of contemplation of independence of international law and to an initial formulation of it. In particular, in the latter part of the thirteenth century, Marino da Caramanico set out arguments which justify the suspicion that a general rule was also being sought after. However, it is not until the early-sixteenth century that a line of reasoning is encountered with Francisco de Vitoria, which actually searches for common ground.

It is at this time, in the late-fifteenth, early-sixteenth century, that the state system also starts to develop, which, in my opinion, now unfettered by the illusions about unity, is the extension of the old post-Roman plurality and the form in which it makes sovereignty of international law the basis of modern international law.

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