Emalus Library Online Documents Collection - Customary Law


Alan Watson *

Source: University of Illinois Law Review ,1984; 1984 U. Ill. L. Rev. 561

* Nicholas F. Gallichio Professor of Law, University of Pennsylvania; M.A., LL.B., University of Glasgow; B.A., B.C.L., M.A., D. Phil., D.C.L., University of Oxford; LL.D., University of Edinburgh. I wish to dedicate this paper to the Molt Illustre Govern de les Valls d'Andorra and to Antoni Morell, Secretari d'Estat. I am grateful to my friends Stephen B. Burbank, Michael H. Hoeflich, Neil MacCormick, and Ann E. Mayer who read a draft of this paper and gave much helpful criticism. An invitation to deliver a lecture in, Andorra gave me a much-valued opportunity to deepen my understanding of customary law.

  ... A proper understanding of the nature of customary law is important for legal historians. For students of European legal history, customary law is particularly important; from post-Roman times to the beginning of the modern legal age in the eighteenth century, the two main elements in European law have been Roman law and legal custom. ... Accepting this reasoning makes it logically impossible, under the current doctrine of opinio necessitatis and custom, for customary behavior to create law. ... Thus, if opinio necessitatis is at the root of customary law, the doctrine does not allow the desuetude of a customary legal rule when that legal rule is remembered. ... Savigny, despite his powerful argument that opinio necessitatis does not fit within the framework which historians usually attribute to customary law, retains the notion. ... The basis of local customary law is frequently treated as custom rather than judicial precedent even though acceptance of the rule actually stems from local judgments rather than from antecedent local behavior. ... To become law, custom, like legislation and binding precedent, must be clothed with the requisite form which marks its official acceptance by the sovereign. ...  


A proper understanding of the nature of customary law is important for legal historians. For students of European legal history, customary law is particularly important; from post-Roman times to the beginning of the modern legal age in the eighteenth century, the two main elements in European law have been Roman law and legal custom. In large measure, the main task of lawyers of that interim time period was to unify or harmonize the two strands of Roman law and custom.

Customary law flourishes in circumstances where law is likely to be the least theoretical. 1 Yet, the nature of any source of law requires theoretical underpinnings regardless of whether these underpinnings are always implicit and never expressed. Accordingly, for custom to be regarded as law in Western private law, more than simple usage must be and is required, even if the usage is general and has long flourished. The principal issue is that one cannot derive an ought from an is. Consistent behavior in accordance with particular implicit rules does not indicate that people should so behave, or conversely should be subject to some sanction if they do not.

The main problem for any theory of customary law seems to be determining the nature of the additional factor required to transform custom into law. The Roman sources clearly indicate that some additional factor is needed to recognize custom as law, even if the nature of this factor is not apparent. For example, the Epitome Ulpiani states that  [*562]  "[c]ustom is the tacit consent of the people, deeply rooted through long usage." 2 The additional factor is expressed by the otherwise tautological "tacit consent" or "tacit agreement" (tacitus consensus). But, this approach raises the question as to what has tacit consent been given? Certainly, tacit consent is not given to the long usage itself, although the tacit consent is rooted in the long usage. Another Roman source, the Justiniani Institutiones, states that "[u]nwritten law is that which usage has approved. For long-practiced customs, endorsed by the consent of the users, take on the appearance of statute." 3 In this instance, the additional factor is expressed by "endorsed by the consent of the users" (consensu utentium comprobati).

Nevertheless, the vagueness of Ulpian is not dissipated as a result of this other explanation. The Justiniani Digesta, however, clarifies the nature of the additional factor by stating that
[d]eeply rooted custom is observed as a statute, not undeservedly; and this is what is called law established by usage. For since statues themselves bind us for no other reason than because they have been accepted by the judgment of the people, then deservedly those things which the people have approved without writing will bind all. For what does it matter that the people declare its wish by vote or by positive acts and conduct? Therefore, it is very rightly accepted that laws are abrogated not only by the vote of him who proposes law, but also through desuetude, by the tacit consent of all. 4
For Julian, the nature of the additional factor seems to be clearer: apparently the custom is law because the people accept it as law.

This article discusses the dominant theory which legal historians have adopted to explain how custom is transformed into law: opinio necessitatis. Although legal historians generally accept the doctrine, it has a number of theoretical failings which hamper its usefulness as an explanatory tool. Accordingly, this article analyzes those failings and an alternate theory that custom becomes law only when it is the subject of statute or judicial decision. Finally, the article proposes nine propositions related to the role of judgments in creating customary law.


For a long time after Justinian, scholars made little progress in defining the nature of the additional factor. 5 Eventually, the idea of  [*563]   opinio necessitatis, which by implication may have its roots in Julian's text, appeared 6 and, despite some opposition, still appears to be the dominant theoretical explanation. The thrust of opinio necessitatis is that individuals purposely follow a certain rule simply because they believe it to be a rule of law. Modern theorists like Larenz have explained the concept in some detail:
One can say the practice must be the expression of an "intention of legal validity" of the community or of a "general conviction of law," provided only that one is clear that this "intention of legal validity" or the "general conviction of law" is not solely a "psychological fact" but the "sense of fulfilling a norm" (of a legally commanded behavior) developing or dwelling in the individual acts of conduct according to the judgement of those sharing the same law. 7

Under this view, custom becomes law when it is known to be law, is accepted as law, and is practiced as law by persons who share the same legal system. But suppose that once the custom is known to be law and is accepted as law, the practice changes. Does the old law cease to be law, and the new practice become law? If this does happen, at what moment does it happen? And, what is the machinery for change?

In analyzing these questions, the legal historian will note two different responses to the change in custom. In the first situation, those subject to the law remember the past custom. In the second, they forget the past custom. In the first situation, which is of greater importance both in theory and in practice, a contrary practice cannot change the law. So long as people remember the past custom as being law, there can be no point on the custom-law continuum at which the new practice usurps what in consciousness has been the law. Accordingly, the outmoded practice must cease to be law before a different law can begin to emerge from customary usage. Unfortunately, the theory of opinio necessitatis contains no mechanism for deleting law that no longer commands approval.

Opinio necessitatis contains a number of theoretical flaws which limit its usefulness in explaining the transition from custom to law. A principal failing is that opinio necessitatis provides no mechanism to incorporate changing customs or to delete law which ceases to mirror  [*564]  common practice. One might try to resolve this inadequacy by postulating that the doctrine of desuetude is inherent in customary law. The doctrine of desuetude states that when a practice that is recognized as law ceases to be followed or to be regarded as law, it ceases to be law. At that stage, but not before, the road becomes clear for the creation of new customary law. Adherence to the new custom before the old customary legal rule becomes obsolete is a factor in making the old legal rule obsolete. However, under the doctrine of opinio necessitatis, overlapping practice does not create a new legal rule because the new practice was not followed in "the general conviction of law." 8 Thus, at the precise moment of desuetude, there is no law on the point at all.

Against this proposed resolution, however, stands Savigny's objection to opinio necessitatis. Savigny points out that within the framework that legal historians usually attribute to custom, 9 custom should not rest on error. Roman sources expressly make the same point. 10 According to Savigny, this principle nevertheless leads to a contradiction without solution. Under Savigny's reasoning, a rule of law should arise first through custom; but, at the time of the first behavior the law was, of course, not in existence. In order to create law through conformity to custom, however,opinio necessitatis should accompany this first relevant behavior. Consequently, the first behavior rested on an error because the behavior was not accompanied by opinio necessitatis and should not be counted towards the creation of the customary law. This analytic approach also applies to the second act of behavior, which then replaces and becomes the first, and so on for all subsequent acts.

Accepting this reasoning makes it logically impossible, under the current doctrine of opinio necessitatis and custom, for customary behavior to create law. A fortiori, when the new customary behavior was being adopted, a different rule of customary law already existed; therefore, any belief that the new behavior conformed to existing law was clearly erroneous. If custom cannot create a legal rule, custom certainly cannot both create and substitute a new legal rule for the established rule which custom abolished.

Thus, if opinio necessitatis is at the root of customary law, the doctrine does not allow the desuetude of a customary legal rule when that legal rule is remembered. Customary law is a "general conviction of law"; hence, it corresponds to what people generally do. People conform to customary law because it is the law. Failure to conform would be an unacceptable deviant act contrary to law." 11 The point is not that customary behavior does not change; rather, under the doctrine of  [*565]  opinio necessitatis, when a rule of customary law exists and is remembered, the rule cannot become obsolete by desuetude. In other words, acts which are known to be contrary to the rule cannot affect the rule's efficacy.

The doctrine of opinio necessitatis presents a further and more important logical difficulty in accepting the doctrine of desuetude of customary law. A legal rule can only fall into desuetude if another legal rule replaces the existing rule regardless of whether this later rule merely states that the first rule no longer applies. But under a theory of opinio necessitatis, the new rule can only come into existence after the old known rule is recognized as extinct. Otherwise, those subject to the law would not be convinced that the new behavior corresponds to the law. Accordingly, no framework exists within which desuetude can operate in compliance with the doctrine of opinio necessitatis.

When those subject to the laws forget the past custom, the prior law effectively is not changed by a contrary practice. If the people completely forget customary law, then as a practical matter, the law does not and did not exist. In analyzing this issue, a theory of obsolescence is unimportant because creating law where none existed before is the only relevant matter. In this regard, historians should note that total amnesia of the customary law can occur only in two particular circumstances. 12 First, the past behavior may have occurred very infrequently. As a result, historians must question whether the behavior ever achieved the common consciousness necessary to become law. Alternatively, the people may have gradually adopted a very different lifestyle with respect to the past custom, e.g., perhaps as a result of migration. In that case, historians should regard the new practice as law, not simply because new law has replaced old law, but because law has been created for circumstances where no law previously existed. In either event, when the people completely forget a rule or supposed rule of customary law, the doctrine of opinio necessitatis unfortunately does not explain how a subsequent contrary practice has, as law, replaced previously existing customary law.

Thus, the doctrine of opinio necessitatis excludes the possibility of changing customary law by subsequent practice, both when the customary law is remembered and when it is forgotten. If, as theorists likely would agree, customary law should correspond with people's actions, then any theory of customary law must provide a means of changing the law through contrary practice. Therefore, opinio necessitatis must be dismissed on the basis of this failing.

Savigny, despite his powerful argument that opinio necessitatis does not fit within the framework which historians usually attribute to customary law, retains the notion. Savigny's solution rests on his  [*566]  general view of law as the "spirit of the people." 13 Under this view, law arises not from individual acts of behavior but from common consciousness. Individual acts of behavior do not create customary law but are merely appearances or indications of a preexisting common conviction about the law. 14 Under Savigny's approach, therefore, the opinio necessitatis exists before the first relevant act of behavior. Consequently, the first act does not rest on an error of law. 15 Opinio necessitatis is thereby saved, but only as a very different doctrine of the nature of customary law. The validity of Savigny's view of custom and opinio necessitatis, however, depends on the plausibility of his general theory of law which current legal philosophers universally reject. 16 Therefore, this article does not further discuss Savigny's doctrine.


Under the preceding analysis, if the theory of customary law is to retain the power to reflect changing practices or to explain the power of customary behavior to create law, theorists must abandon the doctrine of opinio necessitatis. In addition to the prior criticisms, this article raises further objections to the doctrine of opinio necessitatis. The objections and proposed resolution reflect the reality that opinio necessitatis simply cannot explain what actually happens in practice.

John Austin suggests a different theory which legal historians may find more acceptable than opinio necessitatis. According to Austin, customary laws originate as rules of positive morality which arise from the consent of the governed. However, for moral rules to be transformed into positive laws, the state must establish these customary laws. The state may establish customary laws either directly by statute, or indirectly by judicial decree. 17 Thus, under Austin's approach, customary behavior does not make law; custom becomes law only when it is the subject of statute or judicial decision.

Austin's theory is consistent only with his position that law is the command of the sovereign. Under this view, a statute becomes law even before it is enforced by a court decision. 18 Scholars who do not  [*567]   accept Austin's reductionist theory of law will find Austin's theory of custom unacceptable. If one believes that other sources of law, such as custom, exist in theory, then law may also potentially exist without benefit of a court decision. One may argue convincingly that "it is precisely the binding force of custom which challenges [Austin's] initial assumption itself," and that "he failed to explain satisfactorily why the body of rules which he classified as positive morality' . . . lacked the true character of law." 19

A second objection to Austin's theory concerns societal treatment of judicial decisions. Societies that do not treat judicial decisions, even a consistent line of decisions, as binding legal precedents may nevertheless treat decisions establishing a custom as binding. From this viewpoint, a legal historian might claim that custom rather than judicial precedent is law. In this system, when a court finds that a custom exists, the subsequent decision based on that custom is not binding as a decision. Accordingly, the court establishes the preexisting custom as a matter of fact, and the decision, which is not law, merely confirms the preexisting law.

Although these two points detract from Austin's theory, other arguments support his position. First, customary law often does not develop from a "general conviction of law" held by a community. When a general conviction that a practice constitutes law is missing, legal decisions play a fundamental role in determining the rule of customary law. Thus, those living under customary law who wish to reduce the custom to writing complain that the law is difficult to find, know, or remember. For example, the famous thirteenth century Philippe de Beaumanoir justified his Coutumes de Beauvaisis by stating: "it is my opinion and [that] of others also that all customs that are now used [should] be written down and recorded so that they be maintained without change from now on, because through memories that are liable to fade and human life that is short what is not written is soon forgotten." 20 Moreover, in his Conseil, written about 1260, Pierre de Fontaines recorded the customs of Vermondais and claimed that the old customs were much destroyed and that almost all customs were defective. He attributes this disintegration in part to judges who preferred their own wishes to the dictates of custom, in part to those who were more attached to their own opinions than to the practices of earlier generations, and primarily to the rich despoiling the poor and then the poor despoiling the rich. The country, de Fontaines said, was almost without custom. 21

 [*568]   J. A. Brutails, in his celebrated work on the customs of Andorra, 22 also demonstrates the difficulty of knowing the coutours of customary law. He stresses that in a small geographic area the number of lawsuits is limited, and that in the absence of any methodical collection of decisions, the law announced in the cases fluctuates. He also emphasizes that there often is disconcerting uncertitude regarding contemporary and important matters. For instance, when Brutails asked prominent people, magistrates, former magistrates, and judges to ennunciate a widow's rights in the property of her deceased husband, he received five different answers. 23 Indeed, Brutails claims to have often heard that Andorra had no custom, but he insists that Andorra seems no different than other customary systems. Despite numerous and significant gaps in Andorran law, scholars have been uncertain whether the legal system intended that these gaps be filled by reference to Roman, canon, or Catalan law. The common view favored Roman law, but Brutails sought to demonstrate that Catalan law usually prevailed. 24 A much earlier work, King Charles VII of France's Ordonnance de Montil-les-Tours, dated April 1453, records a similar condition: "[I]t often happens that in one single region, the parties rely on contrary customs and sometimes the customs are silent and vary at will, from which great hardships and loss affect our subjects." 25

In the absence of official redactions of the customs which then govern as statutes, court decisions embody the rules. As Philippe de Beaumanoir says in his unofficial redaction: "[W]e intend to confirm a great part of this book by the judgments that have been made in our time in the said county of Clermont." 26 The Maitre Echevin's preface to the 1613 official redaction of the customs of Metz, which required forty-four years to compile, reflects both the difficulty of determining customary law and the necessary reliance upon judicial decisions in doing so:
At last, gentle people, here is the methodical disposition, so passionately wanted, so impatiently awaited, the hardwon redaction of the customs according to which our ancestors so happily administered public business. The customs here, of course, cost much time to lift them from the dust; if so many thorns (that you know about) had not been met with, you would be right to be less pleased with your official, because, truth to tell, one is not at all indebted for what one has rather dragged out than received. But apart from the incredible work employed simply to set out various opinions so that they agree on the same matter, there was need of several Hercules to overcome the difficulties, common and  [*569]   frequent, as much in seeking out the articles in each chapter, as in verifying them. This was not done by giving way to the opinions of individuals, but by a precise and painful reading through of the judgments, memorials and instructions which mossy antiquity left in the strong boxes of the town. Despite all this, the customs are dear to us for the utility the public will receive from them. 27

Brutails claimed, 28 and Ourliac recently has agreed, 29 that the idea of legality is very obscure in Andorra. Brutails and Ourliac apparently believe both that great doubt often exists in Andorra as to which legal rules are appropriate in a given situation, and that ascertaining the precise legal rule to apply does not rank as a high priority in general Andorran thinking. If this is a correct reading of the Brutails-Ourliac position, their belief can be generalized. In customary systems, the nature and application of legal rules are often uncertain, but this uncertainty is not treated as a matter of great concern.

Customary law most often flourishes in small communities with a high degree of kinship, where the law is not based on an academic tradition. Hence, there is a relatively small number of disputes and, in a customary system, disputes delimit the scope of legal rules. In the absence of a strong academic tradition, officials will be reluctant to generalize from specific instances and to extract principles which can be used in different situations. Moreover, those few important decisions that exist may not be adequately recorded or easily accessible.

The example of Andorra as a living customary law system illustrates the relatively minor role of legal principles in a customary law system. The first published Andorran decisions started appearing in a journal, Revista juridica de Cataluna, only in 1963; 30 only two collections exist in book form. Although the collection of Carles Obiols i Taberner covers a twenty-one year period from 1945 to 1966, it contains only ninety-six appellate decisions. 31 Ourliac's collection and commentary cover decisions on appeal to Perpignan from 1947 through 1970. Significantly, both sets of reports each occupy only one slim volume.

Most importantly, there is relatively little demand for a precise knowledge of the legal rules of a customary system. Many disputes in a small community are among relatives, friends, or neighbors. These disputants must live on close terms with one another afterwards, and they often have recourse to less formal means of dispute resolution. Respected friends or relatives may be invited to adjudicate or a  [*570]  recognized approach to adjudication may arise in a particular village. As a result, the appointed adjudicators often reach a decision based on personal perceptions of fairness and reason rather than by searching for a definitive legal rule. Furthermore, in a small community where great flexibility is required, formal legal rules do not necessarily give the most acceptable solution. If a problem situation occurs often enough, however, and if the same decision-makers usually reach the solution, a custom may emerge.

In addition to the difficulty of ascertaining common practices, scholars must cope with the tendency of customary law to originate not from what the people do, but from what the people borrow from other localities. The standard practice, particularly common in medieval France, in which one jurisdiction accepts the law of another system as its residual custom, gives striking testimony to the importance of nonlocal custom. Nonlocal custom plays an important role regardless of whether the outside customary system is the Coutume de Paris, is a neighboring custom as in the pays de droit coutumier, or is Roman law as in the pays de droit ecrit. This wholesale reception of outside custom, though residual, is important for two reasons. First, reliance upon nonlocal custom reduces the adjudicator's discretionary choices in an individual situation. Second, the outside custom may have originated in a society based upon very different economic and political characteristics, such as ancient Rome, or for a much larger, more commercial, and more anonymous center, such as Paris.

Reliance upon nonlocal custom occurs even when a local patriot prepares an unofficial collection of customs. For instance, modern scholars agree that by far the greatest part of the Conseil of Pierre de Fontaines comes from Justinian's Digest and Code," 32 even though the Conseil was intended to be a practical work to use in training a friend's son in the local customs. 33 The same observations apply to the contemporary Livre de Jostice et de Plet, a product of the Orleans area, where the Roman and canon law origins of the rules are hidden and ascribed falsely to French notables. 34

Moreover, unofficial collections incorporating both local and foreign customs may indirectly create customary law. Of course, unofficial works would not themselves create customary law, but the courts frequently treated the unofficial works as evidence of the custom. In those instances, court decisions had a particular relevance: by adopting the rules in the compilations, whatever the origin of the rules, courts expressed the rules as custom.

In perplexing cases, the courts frequently based their decisions upon foreign customs. Thus, Philippe de Beaumanoir also intended  [*571]  that decision-makers use his compilation of custom "for doubtful cases in the said county, by judgments of neighboring lordships." 35 Not only was a foreign source of law borrowed, and treated as the custom of the borrowing jurisdiction, 36 but the borrowed foreign rule was actually that embedded in the foreign judgment. The borrowed rule, however, would have the force of law only when a decision-maker incorporated it in a judgment of the borrowing jurisdiction.


The basis of local customary law is frequently treated as custom rather than judicial precedent even though acceptance of the rule actually stems from local judgments rather than from antecedent local behavior. 37 This treatment raises a question about the role of judgments in creating customary law. The following series of propositions, beginning with those already established, both clarify the question and suggest a resolution.
1. To become law, custom requires something more than behavior.
2. Opinio necessitatis fails to provide the extra factor required.
3. Court decisions declare customary law even when (a) custom is uncertain (and there is no opinio necessitatis) and (b) there is no custom.
4. Proposition three is still accurate when, as in many systems, court decisions do not make law; hence, we cannot simply say the court decision is the entire basis of customary law.
5. Custom officially written down as law is equal to law in the form of a statute; the writing, however, is not proof that the custom was not previously law.
Propositions one through four were established earlier in this article. Proposition five is self-evident. To these propositions we can add:
6. Court decisions are not law, and therefore cannot be the basis of custom becoming law. But, if the decisions declare custom as law even without requiring preceding practice (i.e., combining propositions three and four), then the official declaration of a rule as customary law makes it law regardless of whether the behavior was customary.

Official recognition that particular normative behavior is  [*572]  customary makes such behavior law. But official recognition also entails official acceptance. Hence, the validity of this custom as law depends on its official recognition and acceptance. 38
7. It follows that in societies where decision-makers treat customary behavior as law, there is also an attribution to the people of the power to make law by their tacit behavior.
8. But, this law is created only when decision-makers officially recognize or accept it. Just as the opinion of a sovereign is not law until it is institutionalized by statute, so behavior of the people is not law until institutionalized by an official court decision which recognizes and accepts it. 39
9. As a corollary, if custom has not been expressed in a judicial decision, and hence is not law, but is set out in an official redaction, the custom becomes law but as statute rather than as custom.

This interpretation of the nature of customary law incorporates a theory for the creation or alteration of customary law. Normative customary behavior becomes customary law when it is recognized by the courts as law. Accordingly, the actors need not believe that they are already acting in accordance with an existing rule of law. So long as the courts treat the custom as law, the custom is the accepted customary law. Should the courts hold that the custom has changed, however, then the new ruling becomes the customary law.

These findings on the nature of customary law might support Austin's theory that law consists of the commands of a sovereign that are backed by sanctions. In this instance, a sovereign is defined as someone whose commands are habitually obeyed and who does not habitually obey anyone else. At this preliminary stage, however, this article is not concerned with the validity of Austin's theory as a whole. Rather, this article, for the sake of argument, will for the moment accept his proposition that when judges made a legal rule, that rule is established by the sovereign legislature. 40 If there can be no customary law without a court decision, the concern at this point is whether customary  [*573]   law is at least as much a command of the sovereign as is binding precedent.

Only three factual situations need be considered in assessing the nature of the sovereign's command. First, some writers, notably Vinnius, 41 argue that there can be no customary law under an emperor. In situations where an empire exists, acceptance of this doctrine creates no problem for Austin with regard to custom. 42 Second, in some circumstances customary law is accepted and judicial precedent is binding. This situation also does not create a problem for Austin because decision-makers may resolve any conflict by recognizing that custom forms a rule of law when incorporated in a binding precedent. Third, occasionally customary law is accepted and judicial precedent is not otherwise binding. In this instance, the people as a whole are not the sovereign in Austin's sense. Their behavior creates law, but only at the moment when it is recognized and accepted by the court; judicial acceptance is a necessary precondition to creation of law. Hence, insofar as Austin is correct in arguing that the sovereign's acceptance of a court decision as creating law is thereby a command of the sovereign, a court decision accepting custom as law is equally a command of the sovereign. This point is significant because critics frequently argue that one of Austin's major weaknesses is precisely the difficulty of fitting customary law into his theory. 43

Austin's theory implicitly assumes that all law is legislation and that judges, insofar as they create law, are legislators. My position is different. I agree that binding judicial precedent is both law-making in its own right and a source of law distinct from legislation. Judicial law-making, however, requires that the process be accepted by the sovereign as an appropriate method of creating law. Similarly, custom is a separate source of law distinct from both legislation and judicial precedent. But like judicial precedent, custom must be accepted by the sovereign in order to constitute law. To become law, custom, like legislation and binding precedent, must be clothed with the requisite form which marks its official acceptance by the sovereign. This requisite form requires that adjudicators incorporate custom in a judicial decision. A society may accept custom as law when incorporated in a judicial decision but deny law-making effect to precedent, thereby  [*574]   demonstrating that custom as a means of making law is not simply subsumed into binding precedent.

The conclusions that customary law does not necessarily derive from what people do and that official judicial decisions declare the law illuminate other problems with customary law. To begin with, the legal difficulties described by F. Pollock and F.W. Maitland 44 become understandable in light of these conclusions. Pollack and Maitland report that in the Middle Ages, neighboring villages were frequently inhabited by persons of the same race, religion, and language, who were subject for centuries to the same economic conditions. Yet, neighboring villages often had very different rules; for example, for the central institution of matrimonial property. The villages initially may have shared common means of arranging family property holding, but in each village one approach eventually became fixed as law through the process of judicial decision-making. 45 The final result in any one place, therefore, will contain some element of the arbitrary.

Secondly, the theory of judicially institutionalized customary law sheds new light on a common German medieval practice of resolving legal disputes. Independent towns governed by customary law selected a mother town to whose Schoffen, or adjudicatory body, the daughter town submitted unresolved legal issues. 46 " The daughter town may have preferred, for various reasons, that the mother town provide a ruling. For example, the daughter town may not have had a dominant custom or the custom may have been unsettled or unknown. Further, the mother town's Schoffen may have had high prestige or the local Schoffen may have preferred to distance themselves from local disputes. Yet regardless of how the question to the Schoffen might be framed, the daughter town is not seeking to know its own customary practice.

The practice of submitting disputes to a neighboring town is a particular example of a more general phenomenon: local areas often display lack of interest in establishing local custom. The frequency of borrowing another's custom is itself an example of this lack of interest. A further illustration is provided by the popularity of the Sachsenspiegel. This unofficial statement of early thirteenth century practice in the bishoprics of Magdeburg and Halberstadt was widely used in northern Germany, Poland, the Low Countries, and elsewhere. 47

Yet another example of lack of interest in establishing local custom is the enormous length of time that elapsed between the French royal command to reduce customs to writing and the completion of that effort. In 1453, Charles VII's Ordonnance of Montil-les-Tours  [*575]  required the redaction of the customs in each district, but a century passed before most of the work was completed. 48 The delay is attributable not only to the magnitude and difficulty of the task but also to a frequent lack of interest in establishing the custom. 49

Although a doctrine of judicially institutionalized customary law resolves a number of issues in customary law theory, the doctrine raises other questions. For instance, the traditional explanation for the scarcity of legislation on private law during the Middle Ages may need to be reexamined. The traditional explanation is that great foci of centralized power were lacking, and that kings and other magnates were weak. 50 In some instances this may be a complete explanation, but in other instances the traditional view is clearly inadequate. For instance, magnates frequently granted charters to towns and issued statutes on matters relating to public law. And, as we have seen, it is unlikely that townspeople were so fiercely attached to their customs that they would have bitterly resented magnates' power to legislate on private law. In fact, as the doctrine of judicially institutionalized customary law teaches, people often displayed no great attachment to local customs. 51 The simplest explanation is that magnates frequently had more interesting, more exciting, and perhaps more important things to occupy their time than legislating private law for their subjects.


A major problem for any theory of customary law is determining the nature of the additional factor required to transform custom into law. The doctrine of opinio necessitatis generally has replaced earlier consent theories, but a major flaw of the opinio necessitatis doctrine remains. The doctrine fails adequately to incorporate the creation of new customary law or the deletion of obsolete customary law. Neither deseutude nor Savigny's theory of common consciousness sufficiently resolve the logical failings of opinio necessitatis.

Austin's work suggests that custom becomes law only by the additional factor of state confirmation. Redactions of customary law show that, although the basis of customary law is treated as custom rather  [*576]  than judicial precedent, acceptance of the rule often arises from official judgments rather than from antecedent local practices. Court decisions, not law themselves, function as official sovereign recognition and acceptance of rules of custom as law. Court decisions transform rules of custom into law, regardless of whether the antecedent custom was actually recognized as law. Customs do not become law until institutionalized by inclusion in an official court decision. This theory of customary law may help to explain several otherwise problematic aspects of medieval and practice.

Click here to return to the footnote reference.n1. In view of the theoretical difficulties encountered in determining when a law, the nature of custom in modern "tribal societies" is not discussed here. For the development of a theory of custom in Roman law, insofar as there is one, see Norr, Zur Entstehung der Gewohnheitsrechtlichen Theorie, in FESTSCHRIFT FUR W. FELGENTRAEGER 353 (1969). For a very different view of the formation of customary rules, particularly in international law, see J. FINNIS, NATURAL LAW AND NATURAL RIGHTS 238 (1980). This paper also does not discuss custom as a source of international law.

Click here to return to the footnote reference.n2. EPITOME ULPIANI 4.

Click here to return to the footnote reference.n3. See, e.g., INST. JUST. 1.2.9.

Click here to return to the footnote reference.n4. See, e.g., DIG. JUST. (JULIAN DIG. 84). The accuracy of Julian's account of the people's role in statute-making, or of custom bringing about the deseutude of statute, need not be discussed.

Click here to return to the footnote reference.n5. Because this is not directly an article on the history of legal theory, I have done little more than read the appropriate pages in the GLOSS and typical authors such as Oinotomus, Wesembecius, J. Voet, Vinnius, and Heineccius.

Click here to return to the footnote reference.n6. See, e.g., K.C.W. KLOTZER, VERSUCH EINES BEYTRAGS ZUR REVISION DER THEORIE VON GEWOHNHEITSRECHT 189 passim (Jena 1813); S. BRIE, DIE LEHRE VON GEWOHNHEITSRECHT 1 (1899). Rudolf von Jhering described custom as the "pet" of the German Historical School. See R. VON JHERING, GEIST DES ROMISCHEN RECHTS P2.1 (5th ed. 1894).

Click here to return to the footnote reference.n7. I translated this quotation from K. LARENZ, METHODENLEHRE DER RECHTSWISSENSCHAFT 338 (2d ed. 969) (emphasis in original) [hereinafter cited as K. LARENZ, METHODENLEHRE]. See also K. LARENZ, ALLGEMEINER TEL DES DEUTSCHEN BURGERLICHEN RECHTS 10 (5th ed. 1980). In later editions Larenz is much less explicit, although he seems to hold basically the same opinion. See, e.g., K. LARENZ, METHODENLEHRE, supra, at 345 passim (4th ed. 1979). Larenz expressly adopts Norr's view that the theory of customary law, as such, is unsatisfactory.

Click here to return to the footnote reference.n8. K. LARENZ, METHODENLEHRE, supra note 7, at 338. See supra text accompanying note 7.

Click here to return to the footnote reference.n9. 1 F. SAVIGNY, SYSTEM DES HEUTIGEN ROMISCHEN RECHTS 174 (Berlin 1840).

Click here to return to the footnote reference.n10. See, e.g., Dig. JUST. 1.3.39. This view is generally accepted within the tradition.

Click here to return to the footnote reference.n11. No comparison can be drawn between desuetude of customary law and that of statutes. With statutes, there is no need for a belief that the contrary action accords with the law.

Click here to return to the footnote reference.n12. See, e.g., C.K. ALLEN, LAW IN THE MAKING 136 (7th ed. 1964).

Click here to return to the footnote reference.n13. 1 F. SAVIGNY, supra note 9, at 171.

Click here to return to the footnote reference.n14. Id.

Click here to return to the footnote reference.n15. Id. at 175.

Click here to return to the footnote reference.n16. See, e.g., C. K. ALLEN, supra note 12, at 87. Yet oddly, Austin's theory survives indirectly, without the theoretical trappings, in a number of writers. For instance, see the authors quoted in A. WATSON, SOCIETY AND LEGAL CHANGE 1 (1977); L. FRIEDMAN, A HISTORY OF AMERICAN LAW 595 (1973). In a curious way, Calabresi seems a modern distorting mirror of Savigny. For Calabresi, the judges -- like jurists -- "represent" the people at one level, the current "legal landscape" generally reflects popular desires, and legislation inhibits law from giving the people what they want and need. See G. CALABRESI, A COMMON LAW FOR THE AGE OF STATUTES (1982).

Click here to return to the footnote reference.n17. J. AUSTIN, THE PROVINCE OF JURISPRUDENCE DETERMINED 30, 163 (1954); 2 LECTURES ON JURISPRUDENCE 222 (London 1863).

Click here to return to the footnote reference.n18. Gray argues that statutes are not law but only sources of law, because their meaning is declared by the courts and "it is with the meaning declared by the courts, and with no other meaning, that they are imposed upon the community as Law." R. GRAY, THE NATURE AND SOURCES OF LAW 170 (2d ed. 1921) (emphasis in original).

Click here to return to the footnote reference.n19. C.K. ALLEN, supra note 12, at 70.

Click here to return to the footnote reference.n20. P. DE BEAUMANOIR, COUTUMES DE BEAUVAISIS 71 (n.d.).

Click here to return to the footnote reference.n21. P. DE FONTAINES, CONSEIL ch. 1, 3 (n.d.).

Click here to return to the footnote reference.n22. J. BRUTAILS, LA COUTUME D'ANDORRE (1904).

Click here to return to the footnote reference.n23. Id. at 55.

Click here to return to the footnote reference.n24. Id. at 47 passim.

Click here to return to the footnote reference.n25. KING CHARLES VII, ORDONNANCE DE MONTIL-LES-TOURS 125 (France 1453).

Click here to return to the footnote reference.n26. P. DE BEAUMANOIR, supra note 20, at 6.

Click here to return to the footnote reference.n27. The Preface is not paginated.

Click here to return to the footnote reference.n28. J. BRUTAILS, supra note 22, at 342.

Click here to return to the footnote reference.n29. P. OURLIAC, LA JURISPRUDENCE CIVILE D'ANDORRE -- ARRETS DU TRIBUNAL SUPERIEUR DE PERPIGNAN: 1947-1970, at 12 n.7 (1972).

Click here to return to the footnote reference.n30. Further reports appear in subsequent volumes.

Click here to return to the footnote reference.n31. C. TABERNER, JURISPRUDENCIA CIVIL ANDORRANA -- JUTJAT D'APPELLACIONS: 1945-1966 (1969).

Click here to return to the footnote reference.n32. See A. WATSON, SOURCES OF LAW: LEGAL CHANGE AND AMBIGUITY 45 (1984).

Click here to return to the footnote reference.n33. P. DE FONTAINES, supra note 21, ch. 1, 2.

Click here to return to the footnote reference.n34. See A. WATSON, supra note 32, at 46.

Click here to return to the footnote reference.n35. Preface to P. DE BEAUMANOIR, supra note 20.

Click here to return to the footnote reference.n36. Not all contemporaries saw borrowing of a neighbor's custom as borrowing it for the purpose of adopting it as the custom of the borrower. See G. COQUILLE, COUTUME DE NIVERNAIS (n.d.) (preface).

Click here to return to the footnote reference.n37. Of course one should not take this analysis as meaning that customary law never derives from local behavior. But where it does, there are nevertheless great difficulties in regarding opinio necessitatis as the key factor that turns behavior into law. The elaborate devices designed to discover what the nature of the custom was, such as the "enquete par tourbes" in France or the "Weistumer" in Germany, amply demonstrate that a behavior was not necessarily known to be law, or accepted and practiced as law by persons sharing the same law.

Click here to return to the footnote reference.n38. Critics may object that although official recognition transforms into customary law practices that were not previously customary, habitual normative behavior may nonetheless be law as custom prior to official recognition. This objection is especially powerful if the practice was universally regarded as the custom. The objection, though prima facie plausible, is ultimately untenable. Suppose a case involving a practice universally regarded as custom comes before a court and the court rejects the behavior as incorporating customary law. In that case, one must conclude that the custom cannot be law. Yet, if the decision does not create law then the decision cannot change the law; hence, the normative behavior was not customary law before the decision. The official recognition of normative behavior as customary law makes such behavior law.

Click here to return to the footnote reference.n39. The text of Justinian's Institutes explains that the statement "[t]he will of the Emperor has the force of statute" means that the emperor's will comes to have the force of law when it is couched in the proper institutionalized form. INST. JUST. 1.2.6. Thus, "[d]eeply rooted custom is observed as a statute," similarly means, as we have seen, that custom comes to have legal effect when it is "expressed in the proper institutionalized form, namely, in judicial decision. DIG. JUST. If the statute incorrectly specifies the will of the Emperor, however, the accepted statutory meaning prevails; likewise, if there is no custom, the accepted judicial interpretation prevails.

Click here to return to the footnote reference.n40. J. AUSTIN, supra note 17, at 31.

Click here to return to the footnote reference.n41. VINNIUS, IN QUATTUOR LIBROS INSTITUTIONUM IMPERIALIUM COMMENTARIUS ad 1.2.7.

Click here to return to the footnote reference.n42. The Bavarian civil code of 1756 expressly requires both the will of the people and the consent of the ruler for customary law. See CODEX MAXIMILIANUS BAVARICUS 1.2, 15 (n.p. 1756).

Click here to return to the footnote reference.n43. See, e.g., A. WATSON, THE NATURE OF LAW 3 (1977). One difficulty remains in accepting Austin's theory as a whole. Austin views binding judicial precedent and customary law as equivalent forms of law-making in the sense that both require the consent, acceptance, and tolerance of the sovereign to be law. Of course, that consent, acceptance, and tolerance might be withheld. Nonetheless, consent, acceptance, and tolerance are not equivalent to a command.

Click here to return to the footnote reference.n44. 2 S. MILSOM, HISTORY OF ENGLISH LAW 399 (2d ed. 1968).

Click here to return to the footnote reference.n45. Id.

Click here to return to the footnote reference.n46. For a description of this practice, see A. WATSON, supra note 32, at 31.

Click here to return to the footnote reference.n47. Of the two parts of the Sachsenspiegel, one part survives in over 200 manuscripts, and the other in almost 150. The Sachsenspiegel has been translated numerous times. See id. at ch. 2.

Click here to return to the footnote reference.n48. Id. at 47.

Click here to return to the footnote reference.n49. All this alerts us to the danger of misconstruing similarity of customary law with societal similarity. Although scholars refer to "families" of customary law, one should not deduce that the members of one legal family group are closer to each other in economic, social, and political structure than they are as a group to the members of other legal families. The legal family may result more from the choice of legal approaches than from similarities of customs.

Click here to return to the footnote reference.n50. See F. TOMAS Y VALIENTE, MANUAL DE HISTORIA DEL DERECHO ESPANOL 133 (3d ed. 1981).

Click here to return to the footnote reference.n51. Certainly the compilers of unofficial collections of customary law frequently praise the quality and the descent from their forefathers. But we cannot generalize from these writers. They wrote these works because they were attached to the customs, but this does not imply that the same feeling existed in other members of the community. Indeed, the authors often lament that the customs are not being kept.


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