The Time of Custom and the Medieval Myth of Ancient Customary Law

Medieval custom has been variously described as old, long, repeated, remembered, or immemorial. These notions of the time of customary law can be traced to Fritz Kern’s “good old law.” While scholars have finessed or critiqued Kern’s conception, the assumption that custom had to be viewed as old or ancient law remains. This article examines the temporal framework of custom in lawbooks from late antiquity to the fourteenth century, as well as in modern history and historiography, to trace how and when the language of age and antiquity came to frame custom. When and how, in other words, did a medieval myth of an old, ancient, and even immemorial customary law form? Jurists who tried to define the term, first in late antiquity and then in the high Middle Ages, deployed various notions of time to separate a legal custom that worked like law from habitual practice. The lawbooks that described custom, on the other hand, tended to see it as current or presentist, and it was only around the turn of the fourteenth century that learned definitions worked their way into customary lawbooks. The medieval myth that customary law necessarily had to be old law turns out not to be medieval but modern.