We are witness today, within a context of an increasingly integrated European Union, to the making of a new common legal order which is that of the European Community but also, and intertwined therewith, that of the ECHR. For lawyers that entails the necessity to work towards a ius commune that must be based as much as possible on legal foundations which the cooperating States have in common. Because of the limited competences attributed by the EC Treaty to the Community legislature and the Community courts, it will not be possible to achieve that goal only by means of EC legislative instruments and related case law. For indeed, whereas those instruments and case law will lead to harmonisation of national rules (the bright side of harmonisation), as a result of the limited attribution of competences, that harmonisation will only occur in limited sectors and, therefore, cause new disparities to arise, within each national legal system, between rules affected by European harmonisation and rules in the same area of law which are not affected so (the dark side of harmonisation). In consequence, in order to bring about overall convergence in those sectors of societal life which are to benefit from harmonisation (which is for private law mainly in the areas of contract and tort law), it will be indispensable to uncover, by all means, commonalities in concepts, principles and solutions between the domestic legal systems of the Member States. Only then will it be possible to build the emerging ius commune on common ground, and not to be perceived as a Fremdkörper in the participating States. That is a task of 'strategic importance' which comparative law research in the broadest sense, and by all those involved, must fulfill now and in the future.
In the author's view comprehensive binding codification of relevant areas of the law can be achieved only, for reasons of legal basis, democratic legitimacy and acceptability, by way of a multilateral treaty. Obviously, such Treaty must be prepared by experts from all Member States but on the basis of guidelines as to underlying policy questions and value judgments which have been discussed in European and national parliamentary assemblies in consultation with representative professional and non-professional interest groups. It would then be adopted by the Member States in accordance with constitutional procedures and, once ratified by, e.g. half of the Member States, the codification contained therein, or attached thereto, would enter into force in the ratifying States. In order to maintain uniformity, the Treaty should provide in a preliminary ruling procedure with an existing or a newly established Community court. To avoid the codification work to be carried out, and once in force to prevent it from operating, in the abstract, there is an urgent need to combine the 'top-down' approach inherent in codification, with the 'bottom-up' approach inherent in Source and Casebooks in which materials from all legal systems involved in the codification enterprise are collected. Only by making such materials available, at an early stage, will it be possible to make lawyers of all vintage familiar with each others' legal system and with the legal heritage which they share, and with the underlying societal developments and internal 'moralities'.European Review of Private Law