Customary Law

History

The first scholars to undertake a serious attempt at conceptualizing customary law were ancient Romans faced with the obvious differences between the statutes created by central authorities and the customary law that preceded them, as well as differences between Roman law and the indigenous customary law used in outlying parts of the empire. For all their discussion of what we now call customary law, however, the Romans never developed a single set of attributes pertaining to it; in fact, there is no single Latin term that translates as “customary law.” Further, different scholars emphasized different elements of the larger concept. Emperor Justinian categorized Roman law as either written or unwritten: Written law included senatorial decrees, statutes, plebiscites, imperial decisions, and juristic replies, whereas unwritten law was based on use and experience (usus). Cicero maintained that the legal use of custom requires the consent of the people, although the Romans themselves never achieved this. The great codification of Roman law, the Corpus Iuris Civilis, used the terms mos (manners or habit), mores (morals, conduct or character) and consuetudo (custom, established practice). All of these ideas persist in modern discussions of customary law.

Although most Roman customary law originated in legal decisions, it formed the basis for a great many statutes, as it is believed to have done for the Twelve Tables, the earliest Roman legal codification (450 BCE.). The Roman judiciary incorporated a great deal of non-Roman customary law into the general law (ius gentium) that it developed to govern the non-Roman peoples of the empire. The process of incorporating customary law into legislation has taken place throughout Western history as well.

When Europeans revived Roman law in the twelfth century, some scholars attempted to clarify the received principles. In the thirteenth and fourteenth centuries one such group, the Commentators, arrived at two conditions that have since stood as the hallmark of customary law: longa consuetudo (long use) and opinio necessitatis (the popular conviction that the law supporting the custom be necessary and binding).

A number of later Western legal theorists expressed opinions concerning customary law. Many of these concerned themselves with the evolution of legal systems, and usually considered customary laws to be the earliest of laws. In the view of the social philosopher Thomas Hobbes (1588–1679), customary law had no special power or status by virtue of its age or popular support. If it existed as law at all, it did so only by virtue of legislative action. John Locke (1632–1704) placed legislative authority far above customary law as a desirable social force in his ideal world.

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