The sixth chapter examines the relationship between coutumiers as texts that describe custom, and custom in practice. The difficulty with discussing this is that the coutumiers only begin to be cited in court records at the very end of the thirteenth century and very rarely even then. This was not unusual for the lay courts of northern France in this period, which cited ‘custom’ and not lawbooks or specific precedents. I discuss the relationship between the coutumiers and representations of practice – as filtered through its documentary record-keeping – in two ways. On one level, this chapter shows how at least some people were thinking about court cases that they presided over, took part in, witnessed or heard about. On another, this chapter demonstrates how the coutumier represents practice differently from other remaining records and how coutumier authors used what they saw in practice to extract principles and articulate general rules. Through the coutumiers, we can see how individual actors reshaped specific cases and transactions into general principles, and those general principles into a body of customary law.

This chapter addresses the unbalanced protection of private rights in land and maritime boundary-making. Based on the observation that private rights are more effectively protected on land, the study argues for a reconstruction of the maritime delimitation framework so that private interests in disputed areas are taken into account. The similarities between land and maritime delimitation processes and the common need for the protection of private interests in both settings allow for the application of legal analogy. This allows certain principles which apply in land delimitation to be extended to maritime delimitation. Against this background, the chapter provides a series of short- and long-term means which can be implemented by states and judicial bodies performing maritime delimitation, as well as by policymakers engaged in the development of international law.