The Dependence of the Canon Law

Independence is thus part of the story, but it is not the whole story. The other half — in partial opposition to the first — came from the fact that the canon law was always a partial law.

It turns out that in virtually every aspect, the Roman law was incorporated into the church’s legal system. The process has been inves­tigated with some thoroughness, and that such incorporation occurred is widely known among legal historians. Indeed, much of it is undeniable. There has been further disagreement about the meaning of the process. Some ecclesiastical historians have minimized the canon law’s debt to Roman law, ascribing many of the parallels to common ‘cultural influen­ces’ rather than purposeful borrowing.²¹ Others have thought it more accurate to see the process as a conscious replication or a ‘canonization’ of texts and principles taken from the Roman law.²² The subject may appropriately be considered in three or four historical periods.

The Early Middle Ages

In the centuries before the formulation of the Corpus iuris canonici, it was natural that the clergy should have looked more immediately to the Roman law than to their own canons for most legal questions.

Such limitations - important as they were - did not deprive the maxim of consequence. One was that it provided a clear statement of a principle: the clergy were not to be governed by the laws of the Germanic nations. They were a tribe apart. In a legal world in which the personal principle applied - that is, each person was to be judged by the law that attached to his status or nation - setting the clergy apart from the laity would have seemed (and been) a matter of importance. That ‘there are two kinds of Christians’ - clergy and laity - was to be a guiding principle of the canon law,²⁵ and this maxim can be regarded as one way of stating it.

The maxim’s impact was also evident in the mass of Roman law that purported to regulate church and clergy. The Christian emperors took it as a matter of course that their duties included governance of the clergy, and that was only one part of their spiritual responsibilities. They con­voked church councils and promulgated the decrees of the councils. They enacted laws that regulated the internal working of the church. The first book of Justinian’s Code, for example, begins with titles on churches and their possessions, bishops and clerics, episcopal jurisdiction, heresy, bap­tism, and apostasy. The second last of these was directed principally to establishing the theological principle that the sacrament of baptism must under no circumstances be repeated.²⁷ In other words, even though there were undoubtedly aspects of church government beyond the reach of imperial authority, the line between the two was drawn at a different location than it would be in the twelfth century and beyond. It was balanced, of course, by recognition on the part of the emperors that imperial laws should themselves sometimes follow the canons. ‘The imperial laws should not disdain to imitate the sacred canons’, proclaimed the Emperor Justinian.²⁸ It thus worked both ways. Acceptance of the principle of cooperation on the part of the church in the West is amply demonstrated by the testimony of Christian bishops, including the Roman pontiffs.

In a slightly different but equally compelling sense it was literally true that the medieval church lived by the Roman law. This was so because the church itself took over and incorporated large parts of it. The organizational structure of the church borrowed many of its categories from that of the empire. The division of the church into dioceses and provinces seems to have been inspired by imperial models. Clerical costume, insignia, and functions were borrowed from imperial precedents.³⁰ The law followed the same pattern. Legal rules taken from the Roman law determined many aspects of government within the church. It is found, as outlined above (400), in the pattern and the details of the law of prescription, though subject to the requirement of good faith as shown above (401). That meant that title to church property was subjected to loss through prescription, just as was true for secular rights and chattels. Similarly, in the church’s law of marriage, support for the principle that choice of a spouse should be a matter of free will was found within the civil law’s texts.³¹ Marital property (generally) also followed the patterns laid out in the civil law, despite a Christian dispensation that sought to curtail freedom of divorce. Procedural rules used in the episcopalis audientia, the forum in which Christian bishops acted as judges with the consent of the litigants, were also apparently the same rules and procedures used in the temporal forum.

These and similar borrowings were not meant to imply that the church was being obliged to toe a Roman line. Most of them were matters of choice. This is sometimes described as ‘canonizing’ a civilian text.³² That term is useful in emphasizing that the decision to follow Roman law was a voluntary act, though it should not be used to downplay the canonists’ habitual dependence on the civil law.

The rate of canonical borrowing from the Roman law during these centuries seems to have accelerated as the new millennium approached and passed. Alongside new legislation, the rate of compilation of canonical collections increased from the tenth century onward.³³ So did their sophis­tication. Many of them were now organized by subject matter, rather than by date of the promulgation of the canons in them. This very fact promoted the use of Roman law, for completeness was now an aspiration of the canonists, and where the coverage of the canons was deficient, the civil law might fill the gap. And even where canons did exist, their force might be confirmed and their effect increased if Roman law texts could be added to the mix. The canonical collection of Regino of Prüm (906—915), for example, mixed Roman laws, most taken from the Theodosian Code, together with the decrees of synods and councils and other ecclesiastical sources.³⁴ The canonical collection of Anselm ofLucca (d. 1086), important in preparing the way for papal leadership of the movement for reform of the church, made unhesitating use of Roman law texts in laying out the rules guaranteeing the right of appeal to the apostolic see.³⁵ The Collectio Britannica, compiled ca. 1090 in Italy, contained excerpts from the Institutes and the Digest in several matters of importance to the clergy.³⁶ Similarly, the Collectio in tres libri (ca.

The Corpus Iuris Canonici

For understanding the place of the canon law in the history of Roman law, a survey of the formulation of the church’s ius novum is of the greatest importance — far more so than piecing through the shards of evidence from the centuries before 1100. This is so for several reasons. The Corpus iuris canonici contained the law applied throughout Latin Christendom; it covered a much broader range of subjects than did earlier canonical collections; it was put into effect in diocesan and appellate courts through­out the church; and it attracted juristic commentary and development in a way that none of the earlier efforts did. It also lasted a very long time.

Its first component part, as noted above, was Gratian’s Decretum (ca. 1140). This text has long presented mysteries for scholars; little is known about its author or the circumstances of its compilation. However, recent years have witnessed renewed efforts to discover the original text of the Decretum.³⁸ They may now have been crowned with the success afforded by scholarly consensus of a sort. The theory being advanced is that Gratian’s original text can in fact be recovered and that it was consid­erably smaller than the version that quickly came to be used in the Schools and in practice. The original text was supplemented by texts added by Gratian’s successors. This makes a difference for understanding the place of Roman law in the canons, because it seems that almost all the texts in the final version taken from the Corpus iuris civilis were added after Gratian had completed his initial version. If so, the order would show his own neglect — perhaps his distrust - of the temporal law. What happened next would also tend to show that even within the sphere of the church’s jurisprudence, Roman law was regarded as a useful - perhaps an inevitable - component. Why else would Gratian’s followers have rejected his own decision to exclude it?

Whatever the motivation involved, it is certain that the text of the Decretum used for centuries made repeated use of Roman law. Fundamental questions involving the admissible sources of law, such as the place of custom and reason, were dealt with by lifting texts from Justinian’s Code or Institutes.³⁹ Such usage was not to the exclusion of earlier texts from the church fathers, the popes, or church councils. However, it did seem to place Roman law alongside the canons in stating the applicable law. A dictum of Gratian explicitly recognized that this was so.⁴⁰ Examples are many. One finds that the Decretum incorporated civil law texts in order to delineate the necessary qualifications ofjudges and lawyers.⁴¹ It borrowed a text from the Digest to illustrate the effect of adoption on the prohibited degrees in the law of marriage and divorce,⁴² and it adopted texts from the Code in the service of establishing rules for the interpretation of papal rescripts and privileges.⁴³ The number of such instances is far outweighed by canons that Gratian and his successors took from ecclesiastical sources. Even so, it was by no means negligible. For the future, when the Decretum would serve as a basic text in law faculties, it would set an enduring example.

The second part of the Corpus iuris canonici to be compiled was the Liber extra. It was the work of a Spanish canonist, Raymond of Penafort. In 1234 it was approved as the law of the church and sent to university faculties by Pope Gregory IX. Most of it consisted of papal decretals issued in relatively recent decades, though it also included a few older authorities and some canons from church councils. It included only a tiny number of texts taken over directly from the Justinianic laws. However, some of the papal decretals it contained in fact restated and made use of Roman laws. They embraced the notion that the imperial laws were to be used by the church where the canons did not supply adequate answers to legal ques­tions.⁴⁴ The popes were careful to qualify that usage. To be acceptable in ecclesiastical matters, imperial laws must conform to the laws of reason and they must not contradict express precepts of the church. How large that field would prove to be was never wholly clear. A decretal of Pope Honorius III stated the opinion that it would ‘rarely happen’ that the canons would need help from outside,⁴⁵ but the Roman pontiffs have not always been the most reliable predictors of the future. Roman laws would come to the aid of the canons in many circumstances.⁴⁶

The extent of overlap between the two laws is particularly apparent in the titles found in the Liber extra. When compared to those found in the Code, a real pattern emerges.⁴⁷ On the one hand, some titles in the Decretals had no counterpart in Roman law. For example, titles providing detailed rules about the ordination of clerics, about the duties of archdea­cons, sacrists, and wardens, and about the collection of tithes and ecclesi­astical dues were new. If they were to be influenced by the Roman law, it could only be by analogy. On the other hand, there was also overlap. Titles devoted to the duties of judges, proctors, and arbiters appeared in both; they followed the same path. Titles involving court procedure — the law of presumptions, the place of the litis contestatio, and the regulation of appeals - also appeared in both of these law books, again alike in substance. In several matters involving the dealings of ordinary life - contracts, wills, and gifts, for example - the titles and the substance were also identical.

In arranging the Liber extra, Raymond of Penafort evidently turned to the Corpus iuris civilis. Before that, his immediate model, the Quinque compilationes antiquae, had done the same. The books of the Roman law were available and he used them. Of course, they were being studied and discussed in the Schools, and perhaps it was inevitable that the compiler of an ambitious compilation like the Liber extra should look to what he knew as organizational principles. Lawyers are rarely great inventors.

This should not be taken to mean that Raymond followed civilian models slavishly. He did not. He omitted many of the titles and he added others to their number. For example, the Roman law’s Code had a title on witnesses; in it was a text that dealt with the use of compulsion in requiring witnesses to give evidence.⁴⁸ Raymond inserted a title of the same name into the Liber extra, but he also added a new title called De testibus cogendis vel non - that is, a separate title to deal specifically with the question of when witnesses could, and could not, be summoned and compelled to testify.⁴⁹ In other words, he divided one title into two. We do not know for sure why he did so, but the effort seems to have been to require testimony only when it was absolutely necessary to establish the truth. Giving evidence in court required taking an oath, and an oath raised the possibility of perjury. Men and women ought not to be subjected to that danger unnecessarily. Thus Raymond included a decretal of Pope Clement III stating that unwilling witnesses were to be compelled to appear by threat of excommunication only ‘if otherwise the truth of the matter cannot be otherwise elicited’.⁵⁰ In this way the Decretals both augmented and modified what was found in the Roman law. Of course, the resulting law was not greatly different in its core. The Roman system left considerable discretion on the point to judges, and so would the canon law. A difference remained, however. The canon law was both more careful and more complicated to put into practice. One sees this difference even in the titles Raymond chose to use for his compilation, and it was certainly a conscious choice.

The following books of the Corpus iuris canonici were compiled along much the same lines as those found in the Liber extra. With one exception, they require no special comment. That exception comes from the end of the Liber sextus, in a special title called De regulis iuris. It contained 88 jurisprudential principles. Some stated rules of the law of nature - no one is to be punished who is without guilt, for example (Reg. 23). Others stated starting points for sorting out competing claims to property - prior in time, prior in right, for example (Reg. 54). Others stated what we would call simple interpretative maxims - the greater includes the lesser, for example (Reg. 35). Still others stated overtly ecclesiastical rules - the fault of a person should not redound to the detriment of the church, for example (Reg. 76). Notable throughout the title is that almost all of these Regulae were in fact taken from the same title in the Digest.⁵¹ Pope Boniface VIII, in whose name they were issued, obviously did not disdain to imitate the imperial laws in the development of workable rules for the law of the church. He did not take them all, and he did incorporate some additional maxims. All the same, his title provides a telling example of the dependence of the classical canon law upon the Roman law. It provided his starting point and most of the content that followed.

The canon law that emerged from the compilation of the Corpus iuris canonici was thus touched by the Roman law in three important ways. First, the sources of law and the principles by which the law was inter­preted and put into practice were largely identical. The canonists took over the assumptions they found stated in the Roman law’s texts. Second, although the canonists stressed the church’s independence from temporal control, they accepted that the canon law would use the Roman law when the canons proved incomplete. How large that area would be may have been uncertain, but that it existed they did not doubt. And third, even in areas of the law where the canon law was stated expressly and separately, it often followed the Roman law’s lead. The church’s proce­dural law, for instance, began by restating provisions found in the civilian texts. It normally built upon them, creating a fuller body of law made necessary by the exigencies of court practice, but the starting point was the Corpus iuris civilis.

A telling example - one that includes a little of all three of these sources of influence - occurred with the familiar legal doctrine that ignorance of the law is no excuse. While a mistake about the facts may excuse a person who acts wrongly in accordance with his mistaken belief, the same person’s ignorance of the law will not furnish a legitimate way of avoiding the consequences of violating the law. That was (and is) a basic assumption of Western jurisprudence. The canonists found it stated in an opinion of Ulpian in the Digest.⁵² They took it into the canon law itself, using identical language,⁵³style='font-size:9.5pt;line-height:115%;font-family:"Arial",sans-serif'> and they understood it in the spirit of a still­developing civilian jurisprudence. Thus, the glossa ordinaria to the canon­ical text, the standard tool of interpretation in the canon law, cited both canonical and civilian sources, including the commentary of the greatest of medieval civilians, Bartolus of Sassoferrato, as a key to unlock its meaning.⁵⁴ The two laws stood cheek and jowl in the gloss, and that fusion came to be entirely characteristic of the common law of Europe.

The Early Ius Commune

The European common law as it came to exist in the twelfth century and beyond is called ius commune. The term refers to the combination of the Roman and canon laws that long served as the jurisprudential foundation for European law. Understanding its formation, its composition, and its force in contemporary jurisprudence is therefore fundamental for under­standing the relationship between the canon and Roman laws.

There was, however, a complicating factor. The ius commune was never the only law in force in Europe. Although it was a unity and although its reach extended across many lands, in practice European law was open both to development over time and to variation from one place to another. By force of local custom and legislation, court practice accom­modated rules that differed from what was found in the texts. One geo­graphical area might adopt its own particular regime for inheritance of land — primogeniture, for example. Another might adopt a different rule — such as equal division of real property among a man’s children. Such differences did not undermine the effectiveness of the ius commune.⁵⁵ They simply allowed for local variation within it. The ius commune itself made room for them by recognizing custom as a legitimate source of law. Such variations constituted the ius proprium. It meant the law proper to each particular location.

How, then, was the ius commune itself constituted? And how does one account for its impact and its longevity? Both questions can best be answered by stressing points already made. First, although the two laws were always distinct, with separate legal texts and separate faculties in the universities, they also had many areas of overlap. In most of those areas, the basic rules were the same. The procedural law used in the canon law, for example, was taken in large part from the civil law. Second, both civilians and canonists acknowledged that gaps in their own laws could legitimately be filled with the other’s aid. Emperors had stated that the imperial laws should sometimes follow what the canons contained, and ecclesiastical authorities had repeatedly endorsed the civil law as a useful mine oflaw for church and clergy. Under a legal regime that looked automatically to the past for guidance, such endorsements encouraged a kind of fusion of the two. Third, both Roman and canon law were founded upon an assump­tion that law should aim for perfect justice. The teachings of natural law and Christianity were to underpin the positive law. If canon law and Roman law had different aims, as noted at the chapter’s outset, they shared a conviction that law was more than the command of the legislator. So joined in assumption, the two came to be, as one modern author has put it, ‘as closely connected as the two sides of a coin’.⁵⁶

The point is best understood by examining concrete examples, and many are available. One was mentioned at the end of the previous section: the contents of the glossa ordinaria. From the earliest days following the revival of jurisprudence in the twelfth century, commentators wrote about the meaning of the texts. Their common conclusions appeared in glosses attached to the texts. Defining terms, suggesting interpretations, solving inconsistencies, and calling attention to other relevant texts and rules, the glosses moved the law forwards. In doing, so the commentators routinely drew upon both laws.⁵⁷face=Arial> They moved easily from one to the other.

A straightforward example is provided by Roman law and tithes. Of greatest importance to the material interest of the medieval church, the canon law held that the tenth of the fruits of the earth and of men’s labour was owed to God and was to be collected by God’s delegates on earth, the clergy. The Roman law had no law of tithes, of course. Their source was found in the Bible (e.g., Gen. 28:22). A law to deal with the subject had to be supplied, and one was in fact supplied in a title of 35 chapters in the Gregorian Decretals.⁵⁸ The chapters in it dealt with many trouble­some problems for the clergy. Tithes were not always easy to collect and they had fallen into lay hands in many parts of Europe over the course of the early middle ages. In theory the men who grew crops were required to collect them together and hand over the tenth part to the parson. But what if they sold those crops to strangers without telling them that the tithes had not been deducted? Were the innocent purchasers obliged to pay the parson a tenth part of what they had purchased, or could they escape the obligation if they were bona fide purchasers? If it was the second, the parson had a cause of action only against the seller. The question was raised in a response by Pope Innocent III to the bishop of Ely.⁵⁹ The answer, found most fully stated in theglossa ordinaria, was that the purchaser could indeed be sued to collect the tithe, and the justifica­tion given for this result was taken directly from the Roman law of sale. Transfer of a chattel carries with it all that belongs with that chattel unless the contrary is stated in the transfer.⁶⁰ Thus, the sale of a cow carries with it the calf conceived at the time when the calf is later born. So it was said to be with the tithe. True, the calf was a benefit whereas the tithe was a burden, but the same reasoning applied. One who takes the benefit must also take the burden. Thus, a text from Roman law served to augment the revenue of the church. It was not a great stretch, it seems. For a canonist, it was a normal process.

A slightly more complicated example of such use of Roman law comes from a decretal of Pope Urban III dealing with a contract of marriage entered into under the condition that it would be valid only if the father of the woman consented to it. Urban held that the condition would be effective, even if this placed the decision into the hands of a third party who was not present and would not himself be a party to the matrimonial bond.⁶¹ The glossator sought to support this result, which might have been attacked as a limitation on the pure consent necessary in marriage or as insufficiently certain in outcome to be specifically enforceable. In rejecting this argument, the glossa ordinaria cited a title in the Roman law’s Digest dealing with a conditional sale of a slave.⁶² It held that a sale conditioned upon settlement of the slave’s accounts to the satisfaction of his master was sufficiently definite, because the satisfaction being referred to was that of a reasonable man, not the simple whim of the master involved. In equal fashion, the gloss implied, the same standard could be used in assessing the father’s consent. If he refused agreement arbitrarily, that would be one thing, but if he had a good reason for doing so, that would be something else. The matter could thus be judged by an objective standard, and if that standard had been met, the unfilled con­dition would provide a defence in an action brought to enforce the contract. The parties would then be as free to contract elsewhere as the buyer and seller of the slave had been free to make other arrangements where the accounts were not properly settled. In this case, therefore, the Roman law both furnished support for the papal decretal’s ruling and served to clarify the decretal’s meaning. With a clarification taken from Roman law about the nature of the condition involved, the outcome reached by Urban seemed grounded and workable. Today the conjunc­tion of these two texts may seem incongruous. What does a contract for the sale of a slave in Roman law have to do with a Christian marriage? That question obviously did not trouble the canonist who wrote this gloss. He preferred guidance from a distinction drawn in the texts to speculation about public policy, consideration of the personal nature of marriage, or even concern for proper relations between fathers and daughters. The Roman law found in the gloss met that need.

A third example, taken from theglossa ordinaria to Gratian’s Decretum, involved interpretation of a decree of the Third Lateran Council (1179). One of its canons, known from its first words as Si quis suadente, declared excommunication of any person who ‘laid violent hands’ upon a cleric.⁶³ The gloss posed and answered several questions about it. One was: What if the attacker was a woman? The Latin word quis is masculine, so it might be read so as to cover only masculine attackers. That would fit the so-called rule of lenity familiar in the criminal law. But it was not so, held the gloss. Female attackers were included. Why? The civil law’s text cited in support was a rule found in the Digest holding that women were to be excluded from all public and civil offices.⁶⁴ That now seems a very strange choice to show that attacks by women were in fact covered by the Council’s decree, and it is only when one takes account of the commentary on the Digest text itself that the reason for citing it becomes clear.⁶⁵ The explanation was that women were being disqualified because they were thought by nature to be unfit for public life. This was a rule subject to exceptions, some of which were found in the gloss itself, but it was based on an understanding widely accepted at the time. In this case, the lawyers read it a contrario sensu, meaning that if women were being excluded from an office precisely because the office was public in nature, it necessarily followed that where the office was not a public one, it should be open to women. The text could thus be read as standing for the broader proposition that unless a good reason for excluding women from the coverage of any law existed, they were to be included. It was actually a clever argument. Attacks on clerics could occur anywhere, and the resulting disparagement on the clergy would have been the same, no matter whether the attacker was male or female. No special reason for excluding women existed here, as it had in the Digest text. Hence, the text from the Roman law not only provided an answer to the glossator’s specific question, it also supplied principles of interpretation that could be applied in other parts of the ius commune.

These three instances are but examples of the many uses the medieval canonists made of Roman law. It became second nature to them. In the Schools, canonists would have learned to look to the Corpus iuris civilis for guidance and authority. This was part of their education in law and they would have applied it to their own law. It did not, of course, preclude similar use of canonical sources. For instance, the first example given was actually an exceptional case in the Decretal title on tithes; the great majority of citations found in the glossa ordinaria under that head came from canonical texts. In glossing the marriage law — somewhat ironically, in light of the canon law’s rejection of divorce — more use of Roman law was normal. So there was variety. However, all three examples show what became an almost reflexive response to a legal problem arising in the canon law: look to an analogous situation in the civil law and apply the reasoning or the result found in it to interpreting the church’s own law.

This was one side, and the more significant side for understanding the lasting influence of the Roman law, but it should be noted that medieval civilians, commentators on the Corpus iuris civilis, also made reference to canonical texts.⁶⁶ They did so to a much lesser extent at the stage of the glossa ordinaria than the canonists had in developing their own law. Then, the Roman law was more sophisticated and complete; the canon law was less so at the time Accursius (d. 1263) put together the standard gloss on the Corpus iuris civilis. With the gradual move towards equal status, however, the two laws began to play a roughly equivalent role in the commentaries written on the other’s texts. Much depended on the subject, of course. The canon law provided only a modicum of help with the law of last wills and testaments, for example, and the Roman law was useful only within odd parts of the canon law regulating the church’s sacraments. But the blending together of the two laws, both being treated as authority useful for interpreting and augmenting the other law, had been established as normal practice for European law by the end of the thirteenth century.

The Later Ius Commune

What was a small lake in the twelfth and thirteenth century had become an ocean by the sixteenth century. Scholarly volumes in uncountable numbers had been written to describe, interpret, and advance the ius commune. No ideological divide separates the two periods, but they do look quite distinct from the outside. The enormous growth in the number and range of commentaries gives the later period a quite different appear­ance. There was perhaps less innovation. There was certainly more complexity, more stress on completeness, more repetition of rules, and more references made to a myriad of learned works. The enlargement responded to a real need, no doubt. By all counts, the law courts of the later middle ages and beyond dealt with more litigation than they had earlier, and much of it was complex enough to require massive and detailed treatises. Very likely, the proliferation in scholarship also responded to the growth in numbers of European universities and law faculties. Many of the Doctores who taught in them wished to publish the fruits of their studies. What they published provides a new vantage point from which to view the history of the relationship between the Roman and canon laws.

The first thing one observes is the existence of a class of literature which it is impossible to assign to one side or the other of the line between the two laws. Works on civil and criminal procedure are the most obvious example. The same works were used in both secular and spiritual courts. This was an amplification of an existing habit. Except for their bulk and their complexity, most later treatises on the subject were not different in essence from the procedural manuals produced in the thirteenth century. The Ordo iudiciarius by Tancred of Bologna (d. 1236), or the Speculum iudiciale by William Durantis (d. 1296) cited both laws without discrim­inating between them. Tancred’s discussion of the office ofprocuratores and their role in litigation, for example, contained 7 citations from Gratian’s Decretum, 17 from the Gregorian Decretals, 12 from the Code, 3 from the Digest, and 4 from Justinian’s Institutes.⁶⁷ Here the two laws were truly fused. The same characteristic is found in juristic works of the sixteenth and seventeenth centuries, the principal difference between them and their predecessors being a multiplication of the number of citations to other commentators on the ius commune. Of course, much less of that literature existed at the time Tancred was writing. By 1600 it had mush­roomed, and in the hands of some of the later jurists citation of the opinions of other writers on both the Roman and canon laws became something of a mania. For instance, a discussion from the elephantine treatise by Joseph Mascardus (d. 1588) of a proctor’s disqualification to give evidence as a witness contains a single reference to a text in the Digest, 1 from the Code and 1 from the Gregorian Decretals, but it contains 27 separate citations from the works of other jurists.⁶⁸ In this respect, that treatise was not unusual.

A second and immediately recognizable development in the later works of the ius commune, one in which many of the same characteristics are evident, is the greater attention paid to courts and litigation. Decisiones from the courts were published in great numbers; so were Consilia, the opinions of jurists on questions raised in practice, used by judges to resolve actual cases or by parties to influence the judges; and also works of Praxis about proceedings in specific courts. The authorities in these works were the same as found in most treatises of the time, but here the ius proprium played a greater part. If one looks, for instance, at a collection of Decisiones from the Roman Rota at the end of the sixteenth century compiled by Franciscus Mantica, the same features reappear. In a decision relating to a gift between husband and wife, several texts from Gratian’s Decretum were noted, but most of the citations to specific texts came from the Roman law.⁶⁹ Both the Code and the Digest had long titles devoted to the subject. The Decretals also contained one, but most of its chapters dealt with the effect of divorce on dowry rights, a matter not involved in the case in Mantica’s collection. By contrast, a dispute about whether an archdea­conry could be created without an adequate endowment was decided largely on the basis of the canon law, including previous decisions of the Rota, although two texts from the Digest were also included in it.⁷⁰ Both, however, also contained references to contemporary commentaries on the ius commune. They show clearly that the regular intermingling of the two laws continued and intensified. This was not an academic exercise; it applied throughout Western Europe.⁷¹ Even in the papal court, Roman law had an impact on the law of the church that occasionally seemed greater than that of the canon law itself.

A third feature of the later history of the ius commune deserving of the attention of any student concerned with the relationship between the two laws is the creation of a body of works expressly devoted to the subject. It is called the Differentiae literature. Although it could range more widely, most of it consisted of works called ‘Of the differences between the canon law and the civil’. As its name implies, its announced purpose was to discover and describe the differences that existed between the two laws. How many were there and how significant were they? The very fact of their existence tends to show that lawyers in the sixteenth and seventeenth centuries, from which most of this literature comes,⁷² regarded the subject of the relationship between the two laws as one worthy of study, and some of the literature fulfils the promise of true comparison. That by Heinrich Canisius (1548—1610), for example, begins by considering the areas where, as a matter of principle, the canon law was duty-bound to assert its independence. Where the civil law provided an occasion for sin, he noted, it should have no place in the courts of the church.⁷³ He then went on to give examples. In the longer part of his treatment he listed 54 instances in which either that or some other principle required a difference between the two laws. Each cited a text as authority, usually one from the canon law. Otherwise, he seemed to say, the two laws complemented each other.

This work by Canisius, it should be said, was better than most. The three examples of the class found in the Tractatus universi iuris (1584-86) appear almost to have been the products of a contest to see which compiler could come up with the largest number of differences. The ‘winner’ was Hieronymus Zanettini, whose collection listed 277 separate differences, though a few of them required stretching in order to be counted.⁷⁴ Zanettini ended by asserting that many more existed, but this was a ritual required at the end of such a list; all the jurists included something like it. When viewed objectively, the lists of differences actually confirm the mutual dependence of the two laws. A few were important, but most of the differences were predictable, small, or invented. The similarities were greater.

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