Custom is to society what law is to the state. Each is the expression and realisation, to the measure of men’s insight and ability, of the principles of right and justice. The law embodies those principles as they commend themselves to the incorporate community in the exercise of its sovereign power. Custom embodies them as acknowledged and approved not by the power of the state, but by the public opinion of the society at large. Nothing, therefore, is more natural than that, when the state begins to evolve out of the society, the law of the state should in respect of its material contents be in great part modelled upon and coincident with the customs of the society. When the state takes up its function of administering justice, it accepts as true and valid the rules of right already accepted by the society of which it is itself a product, and it finds those principles already realised in the customs of the realm. As those customs develop and alter with change of circumstance and the growth of public enlightenment, the state is wisely content to allow such development and modification to reflect themselves in the law which it administers. This influence of custom upon law, however, is characteristic rather of the beginnings of the legal system than of its mature growth. When the state has grown to its full strength and stature, it acquires more self-confidence, and seeks to conform national usage to the law, rather than the law to national usage. Its ambition is then to be the source not merely of the form, but of the matter of the law also. But in earlier times it has perforce to content itself with conferring the form and nature of law upon the material contents supplied to it by custom.
A second ground of the law-creative efficacy of custom is to be found in the fact that the existence of an established usage is the basis of a rational expectation of its continuance in the future. Justice demands that, unless there is good reason to the contrary, men’s rational expectations shall, so far as possible, be fulfilled rather than frustrated. Even if customs are not ideally just and reasonable, even if it can be shown that the national conscience has gone astray in establishing them, even if better rules might be formulated and enforced by the wisdom of the judicature, it may yet be wise to accept them as they are, rather than to overturn all those expectations which are based upon established practice.
§ 57. The Requisites of a Valid Custom.
In order that a custom may be valid and operative as a source of law, it must conform to certain requirements laid down by law. The chief of these are the following:—
1. Reasonableness.—A custom must be reasonable. Malus usus abolendus est.[[123]] The authority of usage is not absolute, but conditional on a certain measure of conformity with justice and public utility. It is not meant by this that the courts are at liberty to disregard a custom whenever they are not satisfied as to its absolute rectitude and wisdom, or whenever they think that a better rule could be formulated in the exercise of their own judgment. This would be to deprive custom of all authority, either absolute or conditional. The true rule is that a custom, in order to be deprived of legal efficacy, must be so obviously and seriously repugnant to right and reason, that to enforce it as law would do more mischief than that which would result from the overturning of the expectations and arrangements based on its presumed continuance and legal validity. We shall see, when we come to discuss the theory of precedent, how the authority of judicial decisions is, in general, similarly conditional rather than absolute; a precedent which is plainly and seriously unreasonable may be overruled instead of followed. We are told in the old books that a similar rule obtains in respect of the authority of acts of Parliament themselves. It was once held to be good law, that an unreasonable act of Parliament was void.[[124]] This, indeed, is no longer so; for the law-creating authority of Parliament is absolute. Certain forms of subordinate legislation, however, are still subject to the rule in question; an unreasonable by-law, for example, is as void and unauthoritative as an unreasonable custom or precedent.
2. Opinio necessitatis.—The second requisite of a valid custom is that which commentators on the civil law term opinio necessitatis.[[125]] By this is meant the conviction on the part of those who use a custom that it is obligatory, and not merely optional.[[126]] Custom, merely as such, has no legal authority at all; it is legally effective only because and in so far as it is the expression of an underlying principle of right approved by those who use it. When it is based on no such ethical conviction or opinio necessitatis—when those who use it hold themselves free to depart from it if they will—it is of no legal significance. The only customs which are a source of law are those which are observed by the community as determining the rights and duties of its members.
3. Conformity with statute law.—The third condition of legal validity is that a custom must not be contrary to an act of Parliament. We shall see that certain forms of custom possess not merely constitutive, but also limited abrogative power, being capable of derogating from the old law, as well as of creating new. But no custom of any sort is of any validity as against statute law. The authority of legislation is in English law higher than that of custom. By no length of desuetude can a statute become invalid, and by no length of contrary usage can its provisions be modified in the smallest particular. The common law will yield to immemorial usage, but the enacted law stands for ever.[[127]]
It must not be supposed that this rule is one of necessity, derived by logical inference from the nature of things. It is nothing more than a positive principle of the law of England, and a very different rule was adopted by Roman law,[[128]] and by the various Continental systems derived from it. There the recognised maxim is Lex posterior derogat priori. The later rule prevails over the earlier, regardless of their respective origins. Legislation has no inherent superiority in this respect over custom. If the enacted law comes first, it can be repealed or modified by later custom; if the customary law is the earlier, it can be similarly dealt with by later enacted law. “If,” says Savigny,[[129]] “we consider customs and statutes with respect to their legal efficacy, we must put them on the same level. Customary law may complete, modify, or repeal a statute; it may create a new rule, and substitute it for the statutory rule which it has abolished.” So Windscheid:[[130]] “The power of customary law is equal to that of statutory law. It may, therefore, not merely supplement, but also derogate from the existing law. And this is true not merely of rules of customary law inter se, but also of the relations of customary to statute law.”[[131]]
4. Immemorial antiquity.—The fourth requisite of the validity of a custom relates to the length of time during which it has been established. Here it is necessary to distinguish between two kinds of customs, namely, those which are general—the customs of the realm, prevailing throughout the whole territory governed by the legal system—and those which are local, being limited to some special part of the realm.[[132]] The rule of English law with respect to the necessary duration of a custom is that one which is merely local must have existed from time immemorial. In the case of other customs, however, there is no such requirement. It is there sufficient that the usage should be definitely established, and its duration is immaterial. A local custom must make up for the limited extent of its application by the long duration of its existence, but other customs derive from their generality such a measure of authority as does not require to be supplemented by length of days.
We shall see later, how the idea of immemorial custom was derived by the law of England from the canon law, and by the canon from the civil law. Time immemorial, or time whereof the memory of man runs not, means in the civil and canon law, and in the systems derived therefrom, and originally meant in England also, time so remote that no living man can remember it, or give evidence respecting it. Custom was immemorial, when its origin was so ancient that the beginning of it was beyond human memory, so that no testimony was available as to a time when it did not as yet exist.[[133]] In the thirteenth century, however, a very singular change took place in the meaning of the term. The limit of human memory ceased to be a question of fact, and was determined by a very unreasonable rule of law which still remains in force. In consequence of the interpretation put by the judges upon the Statute of Westminster I., passed in the year 1275, it became an established legal principle that the time of memory reached back as far as the commencement of the reign of Richard I. and no further. From that day to this the law has remained unaltered. The discordance between the memory of man as it is in fact, and as it is in law, has been steadily growing with the lapse of years, so that at the present day the law of England imputes to living men a faculty of remembrance extending back for seven centuries. There is perhaps no more curious example of the conservatism of our law.[[134]]