In 1982, in his monograph on custom in the Middle Ages, the Belgian scholar John Gilissen remarked on the lack of studies in English concentrating on the subject. The situation has not improved significantly. Apart from two articles by Albert Kiralfy and one by Paul Brand, such attention as has been given to the topic has been concerned with particular customs, especially manorial customs, borough customs, and the custom of merchants. The present paper will not fill this gap, but will try to set the uses of the idea of custom in England against the better-studied continental background.

Custom in Roman law

Although the part played by custom, consuetudo, in Roman law is outwith the scope of the present paper, many of the ideas found in the Middle Ages were rooted in Roman soil. It cannot therefore be wholly ignored. Two texts in particular were influential, one in the Digest attributed to Julian, but generally regarded as having suffered some post-classical or compilatorial alteration, and one in the Code ascribed to Constantine. Out of these texts, together with some others of less central importance, we may distil a number of points. First, stress is laid on the long-standingness of a practice: it is referred to, for example, as inveterata, longa, or diuturna. Secondly, it is described as flowing from the (tacit) agreement of the people. Thirdly, it is unwritten, contrasted with written lex. Fourthly, it may or may not prevail over a contrary lex.