Desuetude, in Scots law, that repeal or revocation of a legal enactment which is effected not by a subsequent contrary enactment, but by the establishment of a contrary use, sanctioned by the lapse of time and the consent of the community. Neither the word nor the idea attached to it is familiar to the law of England—where the corresponding term is non-user. The rule in England is, that a statute once formally enacted by the legislature, remains in force, however unsuited it may be to the altered conditions of society, till it be repealed by another statute. The repeal may be by implication, but here the law watches with a jealous eye. Such repeal 'is to be understood,' says Blackstone, 'only when the matter of the later statute is so clearly repugnant that it necessarily implies a negative.' So far was this principle carried, that it was formerly the rule, that if a statute repealing another was itself repealed afterwards, the first statute was revived without any formal words for that purpose. But this rule was changed by 13 and 14 Vict. chap. 21. In Scotland, an opposite principle prevailed, and it is still held that acts of parliament made before the Union may lose their force by disuse, without any express repeal, or 'go into desuetude,' as it is commonly said. The same may be said of the general orders (Acts of Sederunt, as they are called) of the Court of Session. But by desuetude is meant something more than mere non-use for a period of time, however great. There must be contrary use of a positive kind, inconsistent with the statute, and of such a kind as to prove the altered sense of the community; there must, in short, be consuetudinary law in a negative sense; and the so-called desuetude thus amounts to a repeal of statute law by consuetudinary law.
Both rules are liable to objections. The result of that followed in England has been that statutes have remained on the statute-book without formal repeal after their enforcement had become morally impossible. A curious example of this occurred in the early part of this century, in which one of the parties to an ordinary civil suit challenged his adversary to 'judicial combat,' founding his claim to do so upon an unrepealed statute, and it was held that in point of form his right could not be disputed (see DUEL). But since 1869 the English statutes have been by the Statute Law Revision Acts weeded to a great extent of all obsolete and inconsistent enactments, and a new edition of Revised Statutes has been published, containing as far as possible only such enactments as are in force. The rule in Scotland is the same as the English as regards all statutes made since the Union; but as regards the older Scotch statutes, the difficulty still exists, in dealing with enactments more or less forgotten or violated, how to determine what constitutes such contrary use as to support the plea of desuetude. The effect of the plea of desuetude has been curiously illustrated in some modern cases, where the validity of certain old Scots acts against Sabbath profanation was questioned. In two cases, in 1870 and again in 1887 (when a person was charged with keeping open a pie and lemonade shop in contravention of the Act of 1661), the plea of desuetude was disregarded.