Customs as legal general rules
The generalization of customs faces obstacles associated with the publicity of law and with non-cooperative behaviours. To overcome these, Hobbes proposes a contractual solution: the sovereign power makes law a national public good and at the same time is the judge.
Contractual codification solves both the problem of induction in that law is publicly and explicitly declared to the people (Hobbes, 1966) and the problems of non-cooperation because sovereigns establish themselves in the position of final arbitrator. However, the very nature of customs precludes any contractarian device. A social contract demands explicit agreements, which obviously involve individual knowledge of the content of the covenant. Hume’s rejection of the social contract is justified by the lack of obligation it would convey, since it is plainly founded on interest. By contrast, the enforcement mechanism associated with customary rules has to respect the spontaneous nature of the latter.Customary systems of law meaningfully exemplify the transformation of customs into customary legal rules. The function of the corresponding institutional arrangements is to ensure that law can effectively be allowed to spread in the geographical space as well as in the space of preferences. First, rules of law are considered as an extension of customs. From this perspective, judges do not have the responsibility even less the capacity to create rules. They merely act as arbitrators whose role consists in discovering rules through individuals’ actions and clarifying already existing norms. In other words, it is impossible to distinguish between de jure and de facto rules (Hayek, 1980, p. 76): customs emerge de facto and may later become codified (de jure) legal norms. Obviously, judges cannot rely upon an effectively infinite knowledge of human behaviours and cannot pride themselves on being a central planner.
The required knowledge to select the best rules and, after that, to evaluate the consequences of their choices, exceed their capacities. What is identified as the major ability of judges is their experience and their ability to refer to what was previously done in the same kind of circumstances. Judges should rely on prevailing customs and progressively amended practices. This position has been defended since the very origins of the spontaneous order tradition by jurists like Sir Matthew Hale or Sir Edmund Coke. For instance, Hale prefers ‘a Lawe by which a Kingdome hath been happily governed four or five hundred years than to adventure the happiness and Peace of a Kingdome upon some new Theory on my owne’ (quoted in Barry, 1982, pp. 15-16). At the same time, since no one can behave as a central planner, the rule of precedent will carry out this task. The importance of the stare decisis principle provides a clear illustration of the role of precedent in the decisions taken by judges. Every codification decision belongs to the tradition, confirms it and reinforces it.Second, the role of oral transmission of tacit rules is particularly well developed. Iceland in the Middle Ages provides an example of such a periodical recitation of articles of law. Another part of the judicial device which is required for customs to be legal rules lies in the fact that justice is dispensed by groups of men, usually known as Leiroir (autumn assemblies). Whatever their label, these groups perform the same function, namely to gather together individual members of different communities to impart to them the rules of law. Finally, until the twelfth and thirteenth centuries, the English system of customary law exhibited many specialized courts of justice (county courts: local law; church courts: canon law; borough courts: merchant law; courts of a baronial overlord: feudal customs). This was clearly a means of dealing with a problem of induction in the space of preferences. The aim was to provide an optimal allocation of judges’ abilities between the different kinds of litigation.