This book is divided into three parts. The first part con­tex­tu­alizes the cou­tu­miers and their authors in the legal land­scape of thirteenth- century northern France in three ways. I con­tex­tu­alize them within the struggle to define custom from late antiquity up to the time of the first cou­tu­miers and discuss prece­dents for written secular law before the cou­tu­miers (Chapter 1). I then examine the pre­dom­inant choice of the first cou­tumier authors to write in the ver­nacular and, to the extent that they can be dis­cerned, their per­cep­tions of laymen who par­tic­i­pated in lay courts (Chapter 2).

Unwritten law, or ius non scriptum, was a prominent defi­nition of custom in the later medieval period developed espe­cially in learned circles. Though ‘written custom’ should be acon­tra­diction, this was unevenly per­ceived. Unlike the authors of the Bracton treatise in England, for instance, the cou­tumier authors did not seek to under­stand or legit­imate their writing of custom within this learned framework. Those cou­tumier authors who addressed the question of writ­tenness viewed the idea of ‘written custom’ as unprob­lematic. Instead, they saw writ­tenness and its lack through a prac­tical lens, as an aspect of custom’s potential to be retained in memory. This does not mean they viewed written custom as ‘fixed’. Writing in a time of fun­da­mental legal change, they under­stood that even the custom expressed in written text was mutable. While writing custom could help to keep it in memory, it was poten­tially changeable in future ver­sions of the text (Chapter 3).

The second part extends the argument about the devel­opment of ver­nacular law by looking at issues of juris­diction and authority.The cou­tu­miers expose real anx­i­eties about the bound­aries of power. Expressed either tacitly or explicitly, these anx­i­eties appeared in con­cerns over juris­diction, and espe­cially eccle­si­as­tical juris­diction (Chapter 4). In con­trast to legal his­tories that usually approach the issue of authority in written custom by exam­ining the reliance on and influence of Roman law, I look instead at Roman law within the general use of sources and their asso­ciated citation prac­tices in order see what the authors of cus­tomary law them­selves counted as author­ities (Chapter 5). Roman law was cer­tainly an important source for some cou­tu­miers, but rather than treat it rev­er­en­tially as an authority, their authors used Roman law to build some­thing new, lay, cus­tomary, and ver­nacular. The question, then, is not so much about the influence of Roman law as it is about the agency of cou­tumier authors who cus­tomized some­thing dif­ferent out of this as well as other sources.

As the third part of this book con­tends, ‘ver­nacular law’ was not only law expressed in a ver­nacular lan­guage but also a dis­tinct con­cep­tu­al­ization of law that itself created new pos­si­bil­ities for legal thought. The three final chapters explore these pos­si­bil­ities. I begin with the rela­tion­ship­be­tween the cou­tu­miers as texts that describe custom and custom as it is reflected in other remaining records of practice (Chapter 6). I demon­strate how the cou­tu­miers rep­resent practice dif­fer­ently from other con­tem­porary records of practice and how, in part, their authors used what they saw in practice to extract prin­ciples and artic­ulate norms. By offering this form of gen­er­al­ization, the cou­tumier authors helped transform ‘custom’ into ‘cus­tomary law’. I argue that the goal of these legal texts was to change pat­terns of thought and teach lay people a set of ideas and skills that would permit them to perform con­vinc­ingly in lay court (Chapter 7). The last chapter then examines the larger effect of written custom on legal culture. The new tech­nology of writing com­bined with the social choice of the ver­nacular per­mitted cus­tomary legal ideas to be trans­mitted and­shared outside their local setting. This increased cir­cu­lation of ideas was a com­ponent setting the stage for thede­vel­opment of a French ‘common law’ (Chapter 8).