For custom to be regarded as law, more than simple usage is required, even if the usage is general and has long flourished. 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 is determining the nature of the additional factor required to transform custom into law. Here you will study this issue by considering some five theories of customary law, namely the tacit consent theory, the theory of opinion necessitaties, the common spirit of the people, sovereign recognition and judicial recognition.

The tacit consent of all: Can you guess how this theory of customary law might define customary 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 custom is the tacit consent of the people, deeply rooted through long usage. Another Roman source document states that unwritten law is that which usage has approved. For long-practiced customs, endorsed by the consent of the users, take on the appearance of statute. In this instance, the additional factor is expressed by "endorsed by the consent of the users. The element that transforms custom into customary laws is deeply rooted custom is observed as a statute, not undeservedly; and this is what is called law established by usage. For since legislation binds because it has been accepted by the judgment of the people; then those things that the people have approved without writing will bind all. Thus, custom is law because the people accept it as law.

Can you state the problems of this theory? The theory of the tacit consent of all tells that custom would be transformed into customary law if and only if all members of a given community agree on such transformation. Thus, one problem is that it is almost impossible to get the consent of all members of a given community on each and every custom to be upgraded to customary law. Is it not impractical to obtain the assent of all? It is almost impossible to obtain the unity of minds of all to the transform of custom into customary law. The second criticisms directed against the tacit consent of all theory is that customary law binds every member of a given community; its breach would entail sanctions. But this serious matter is reduced by the tacit consent theory of customary law to a covert consent not an open and explicit consent. The point is that the idea of explicit consent makes more sense that the idea of tacit consent in such type of serious matters.

Theory of Opinion Necessitatis: For opinion necessitatis, individuals purposely follow a certain rule simply because they believe it to be a rule of law. 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 judgment of those sharing the same law. 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.

Can you comment on this theory? Assume 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? The theory of opinion necessitatis fails to adequately answer these questions.

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, 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. The theory of opinio necessitatis contains no mechanism for deleting law that no longer commands approval. 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.

the doctrine of opinio necessitatis 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. The point is not that customary behavior does not change; rather, under the doctrine of opinio necessitatis, when a rule of customary law exists and is remembered, the rule cannot become obsolete by desuetude. In other words, acts that are known to be contrary to the rule cannot affect the rule's efficacy

There is another problem in the doctrine of opinio necessitatis. 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. People may have gradually adopted a very different lifestyle with respect to the past custom, e.g., perhaps as a result of migration. We 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. When the people completely forget a rule of customary law, the doctrine of opinion necessitatis does not explain how a subsequent contrary practice has, as law, replaced previously existing customary law. Thus, the doctrine of opinion necessitatis excludes the possibility of changing customary law by subsequent practice, both when the customary law is remembered and when it is forgotten.

The Common Spirit of the People: This theory was developed by von F. Savigny. 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.

The common spirit of the people is criticized for its several failings. First, this theory presents a nation as a corporate entity; it assumes that a nation manifests unity of action when it comes to developing customary laws. Second, the theory hides several historical instances where the minority has imposed its will on the majority in the form of laws. Third, the theory dismisses the possibility of a country borrowing laws from other countries. Finally, the theory is criticized for being narrow or ethnocentric.

Sovereign Recognition: John Austin suggests that 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. 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 implicitly assumes that all law is legislation and that judges, insofar as they create law, are legislators. Austin's theory is consistent 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. Scholars who do not accept Austin's 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. 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.

A second objection to Austin's theory concerns societal treatment of judicial decisions. Societies that do not treat judicial 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.

Therefore, the defects of the sovereign recognition theory of customary law are that the state has no moral authority to validate or invalidate the wishes of the communities as reflected in their customary laws, that the state may distort the authenticity of customary laws in the course of validating them, that it is unsound to state that the state is the only valid source of legal rules and that customary laws are already valid by the assent of the community and thus not need to validate them any more.

Judicial Recognition: 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. This treatment raises a question about the role of judgments in creating customary 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 demonstrating that custom as a means of making law is not simply subsumed into binding precedent. 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.

In sum, 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 opinion necessitatis generally has replaced earlier consent theories, but a major flaw of the opinion necessitatis doctrine remains. The doctrine fails to adequately incorporate the creation of new customary law or the deletion of obsolete customary law. Savigny's theory of the common consciousness fails to resolve the logical failings of opinion 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 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.

The theory of Desuetude: Can you explain the theory of desuetude? A full appreciation of this theory warrants asking the following four questions. First what is desuetude? This term is a generic term. Desuetude means anything that is no longer in use; but originally designed to serve a given purpose. As applied to customary law, what is the meaning of this term?  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. It simply means the customary law in force has lost its obligatory force. The third question is the reasons why customary law may lose its obligatory force. Customary law may lose its obligatory force owing to internal and external changes in the community that developed the customary law in the first place. The community has developed the customary law in order to solve a given legal problem and when the context in which the customary law changes the customary law itself must disappear or be modified. The final question in respect of theory of desuetude is whether the outdated customary law might revive.

History of Customary Laws:

This sub-section describes certain information relating to the origin and development of customary laws in different legal traditions.

Origin and Development: The history of customary law is as long as the history of human kind. In those early times where there was no codified law by institutionalized organ of the state, people were governing themselves in a certain way. The evaluation of law began before history was recorded with laws built upon one by one as disputes were settled. In fact the development of rules in society predates both courts and the written law. For thousands of years, customary and private legal systems alone ordered human activities. The obligation to behave in a certain way in a particular community became a customary law in that particular community the failure to observe result in a sort of sanction from the community against the deviant. This is so because behind customary law there is moral force to behave in a certain way. They became compulsory and have acquired the force of law with respect to the place or subject matter to which it related.

“… Rules (i.e., customary laws) can evolve and emerge spontaneously as the unintended outcomes of individuals separately seeking their own goals. Such laws are less likely to be violated than enacted authoritarian laws because they require voluntary acceptance by individuals in recognition of reciprocal benefits received, As a result, customary law is less likely to require adjudication.

Since its inception, customary law has undergone considerable change as the society is always in a constant motion. Customary rules also respond to the particular needs and interests of the social group. When these change, customary rules tend to change though the way they change is influenced by the nature of previous   rules…  Some customary law lost its power as there is a constant mobility and interaction of the society. As a result, there is a move from old customary law to modern law. As certain activities of human beings are beyond the reach of customary law, it is supplemented by modern law. In ancient societies a greater degree of psychological conformity was necessary. So custom is stronger in ancient than modern societies. In the present world, custom is conserved in the rural districts among less developed groups than in the cities.” Circumstances were slowly changing that people themselves were unaware of the change. So law and custom change with those circumstances. The old practice were forgotten, however, people believe that they are still following the percepts of their ancestors, when the truth is that they have long since abandoned them.

Customary Laws in Some Legal Systems: Customary law is one of the elements of the civil law tradition. The modern law of merchant, whose origin is usage, has passed three successive historical stages.  The first stage was the situation where by the existence of certain usage in particular business was proved by the witnesses called by the party before the court; the second stage was the time when the court took cognizance of the existence of certain custom in particular transaction. This is so by referring to earlier decisions of similar question of facts and /or laws. The second stage of development is reached when the courts take judicial notice of the custom in question, so that it no longer requires to be specially pleading or proving in the particular case. It has already been sufficiently proved in the previous cases, and has received the authority of the precedents established by those earlier cases.

The last stage of merchant law is its incorporation into the formal national laws. This law has its first source in the conventional law, and secondary source in the precedent. The law of bill of exchange, and the law of marine insurance which were both in their origin part of the customary law merchant, have now completed its normal course of legal development.

It is said that conventional custom is the source of modern law merchant. The bulk of the law as to bills of exchange and other negotiable instruments, bills of lading and marine insurance, has originated in this manner as customary law. Law so derived from the conventional customer of merchants is known as the law merchant.

Prior to codification, Germany used customary laws. European countries regulated themselves, among other, by customary practices and customary laws in the Middle Ages.

Before the French Revolution, traditional customary laws prevailed in the north. The rules were Germanic customs while Roman law influenced the southern part of France. Roman law gradually spread northwards. The French legal system was not sharply divided because there were written rules influenced by Roman law but containing strong Germanic elements in the south. And Roman law was not entirely rejected in the North.

France received Roman law not because it had been laid down by Rome, but on the ground that it had been accepted by custom or by reason of its quality.  The existence of diverse customary rules and edicts created some degree of legal uncertainty in France.

France’s need for a single, unified code of laws had been keenly felt even before the collapse of the ancient regime. Whereas, southern France had inherited Roman law, northern France was ruled by a system based on customary law. The two systems were fundamentally different. The laws differed not only from province to province but also from town to town. Nor were the laws always rational. Louis XIV, the Sun King, had summed up his approach to lawmaking with his famous phrase “It is legal because I wish it.”

Before the introduction of the Civil Code, a patchwork of customary laws based on tradition and the whim of the monarch had ruled throughout the continent. The new Code introduced the concept of a unified, logical system based on general principles of law. This facilitated the export of the ideas of the French Revolution beyond French borders.

In their move to eliminate legal uncertainty, some practitioners attempted to record customary laws of particular regions in France. It remained true, however, that the customary laws of Northern France depended principally on oral tradition. The judge who did not know the appropriate rule of the relevant area had to discover it by interviewing local inhabitants. The proliferation of custom and the difficulty of discovering their content led to great legal uncertainty.  As a result, a French king in the 15^th century declared that the customs of the various territories should be written down. The king also ordered that those, which were already recorded, should be drafted anew.

The intervention of the kings in having the customs recorded met with opposition from some territories. The intervention and the effort to write down the various customs in France strengthened the power of the traditional customary laws to withstand Roman Laws. The recording of customary rules saved France from the massive reception of Roman law, which took place in Germany. The codification of customary laws created conflict of different customary rules. Recording of customary law in France had brought about legal certainty. Yet, it could not diminish the substantial differences between them. The recoding efforts of French customary laws made the difference among such rules sharp and conspicuous.

Case law grew up in England because of the accident of the early English judges being Normans.  They were foreigners to England and they were bound together by an ESPRIT DE CORPS, which made them respect each other's decisions, especially when these decisions dealt with matters, which were strange and unfamiliar to them. If  half a dozen of you were to be sent to the wilds of  Africa as judges, naturally when you meet together you would discuss the strange customs of the Africans, and if in a case you feel that what you heard from another judge would help in solving the problem. You would naturally remember that example and follow the precedent. In this fashion in England the Norman judges when they used to meet at the Temple discussed their cases, and started the practice of following each other’s decisions. Once the Bar discovered that the best argument in favor of a particular case was the decision of a brother judge in a similar case, they began to take notes of cases by these judges and in that manner law reporting came in to existence. Law reporting became an established practice in this manner, and now as you know the opinions of one judge are regarded as an authority binding on  the other judges. The growth of case law in England was also accelerated by the reaction that set in against the reception of Roman law. On the continent, particularly in countries like Germany and France, the indigenous or local law was found to be unsatisfactory as society progressed, and whenever a complex case came up, to which the local law could supply no remedy, it was the practice of the judge to apply Roman law, with the result that at the present day, a large part of Germany and French law is nothing more than Roman law.

Also in England the local law was found to be unsatisfactory with the advance of civilization, and the same remedy of introducing Roman law was attempted. But the common lawyers in a body resisted it, and to meet the exigencies of the situation, the judges resorted to a fiction, namely, that there was no legal problem that could not be solved by the application of customary law, and that every judge carried about in his brains a complete body of such law ''of amplitude sufficient to furnish principles which would apply conceivable combination of circumstances''. A judgment or declaration of a judge was supposed to be in conformity with the custom of the land, and when such declarations were followed by subsequent judges for the sake of conformity, there grew up in England the practice of following precedents. It is possible as Maine points out, that the judges were influenced by Roman law principles, and that they borrowed in large quantities from the Roman law, but what is important for us to note, is that they did not rest the authority of their pronouncements on either the Roman law or on the theory of IPSE DIXIT, but on the fiction that their judgments indicated the custom of the land. It was always as indicating the custom of England, and not as an authority, that these decisions were acted upon and followed during the 13^th and the 14^th centuries.

Customary laws that were legitimatised when found out to be in line with the teaching of the Holy Veda. There are factors that led to the differing interpretation of the teachings of the Holy Veda; one of which was customs and practices surrounding the others affected their respective version of Veda. Islamic law was also subjected to different interpretations owing to, among others, the customary laws and practices of the Muslim communities living in different geographical conditions.