In principle, the relationship between national and Community law is given concrete form in the national legal context in which the provisions of Community law take effect. This has the effect of limiting the penetration of Community law. Most of these limitations however have to answer to a 'minimum stan-dard' set by Community law, such as the requirement for effective legal protection: the national laws through which Community law is put into effect must ensure the effective legal protection of rights arising out of Community law. While the requirements formulated in Community law as such are acquiring settled form, their foundation on the one hand, and their scope on the other hand is far from clear. Another important consequence of the restrictions by Community law upon national procedural law is the partial harmonization of the relevant national law. How far this harmonization will or should go, and whether this is a desirable process, remains a moot point.
Examples of this are: the role of Community law in providing constraints and hence influencing national law on evidence and other national procedural law, doctrines such as the abuse of law, and arbitration rules. Another example is the question of the public policy nature of Community law, a question on which there has been hardly any theoretical work.