CUSTOM, in general, a habit or practice. Thus a tradesman calls those who deal with him his "customers," and the trade re sulting as their "custom." The word is also used for a toll or tax levied upon goods (see CUSTOMS).
In law, such long-continued usage as has by common consent become a rule of conduct is termed custom. The adoption of local customs by the judiciary has undoubtedly been the origin of a great portion of the English common law. Blackstone divides custom into (1) general, which is the common law properly so called, and (2) particular, which affects only the inhabitants of particular districts. The requisites necessary to make a particular custom good are : It must have been used so long that the memory of man runneth not to the contrary ; (2) it must have been continued, and (3) enjoyed peaceably; (4) it must be rea sonable, and (5) certain; (6) it must be compulsory, and not left to the option of every man whether he will use it or not ; (7 ) it must be consistent with other customs, for one custom cannot be set up in opposition to another. Customs may be of various kinds, for example, customs of merchants, customs of a certain district (such as gavelkind and borough English), customs of a particular manor, etc. The word custom is also generally em ployed for the usage of a particular trade or market ; for a trade custom to be established to the satisfaction of the law it must be a uniform and universal practice so well defined and recognized that contracting parties must be assumed to have had it in their minds when they contracted.
In the history of France the term "custom" was given to those special usages of different districts which had grown up into a body of local law, as the "custom of Paris," the "custom of Nor mandy" (see FRANCE : Law and Institutions).