Consuetudo ex certa causa rationabili usitata privat communem legem

Author: Rishi Tibrewal, Damodaram Sanjivayya National Law University


The literal meaning of the maxim ‘Consuetudo ex certa causa rationabili usitata privat communem legem’ is, a custom founded on a certain and reasonable ground supersedes the common law.[1]


A custom is an ongoing pattern of behavior which may be viewed as setting the standard of conduct for members of society by the consent or express agreement of the community observing it. If people find that any action is desirable, useful, fit and acceptable to its nature and disposition, from time to time it is used and practiced, by which the custom is frequently used and multiplied. Custom is a norm of behavior that society naturally respects, as tradition, custom and practice, but is not codified in the law. There are, however, several requisites to the validity of a custom, which can here be but briefly specified. First, it must be certain, or capable of being reduced to a certainty. Secondly, the custom must be reasonable in itself. Thirdly, the custom must have existed from time immemorial. Fourthly, the custom must have continued without any interruption.

The fact that the custom is contradictory to a specific maxim or rule of common law does not cause the custom to be unjustified. Under that principle, custom is not always unreasonable, when is to the benefit of the people at large, even if it is harmful to the interests of the individual person. On the other hand, a particular custom which contradicts the public good, or which is detrimental or damaging to many, and which exclusively benefits a specific person, is opposed to the law of reason, for it could not have had a reasonable origin.

Muggleton v. Barnett

This case established the maxim of Consuetudo ex certa causa rationabili usitata privat communem legem.[2] The facts of this case were as such – Edward Muggleton purchased a manor in 1772 which had a custom that upon death of the owner, it shall go to the youngest son. In the absence of a son, it would go to the daughters as parceners, and in the absence of any children, to the youngest brother. Muggleton died in 1812, leaving behind two granddaughters, the daughters of his only son. One of the granddaughters died unmarried and the second died leaving a single son who died in 1854. On his death, the youngest son of the youngest brother of the purchaser brought an ejectment.

The judges agreed that the law of inheritance could not be applied here. Chief Justice Cockburn stated in the judgment “local customs are remnants of the older English tenures, which, though generally superseded by the feudal tenures introduced after the dominion of the Normans had become firmly established, yet remained in many places, probably in manors which instead of passing into the possession of Norman lords remained in the hands of the English proprietors. These customs, therefore, are not merely the result of accident or caprice, but were originally founded on some general principle or rule of descent.” Thus, the plaintiff succeeded.

[1] Litt. 169; Co. Litt 113; Broom, Max. 919.

[2] Muggleton v. Barnett, 2 H. & N. 681.