As multiple actors have become involved in the development of European private law, interdependence has developed. Multilevel governance theories and pluralist insights imply that the coexistence of actors may lead to both problems and benefits for European private law.
Case studies of one specific area of law should make these perspectives more specific. Thus, the case studies in subsequent chapters 4 and 5 will ask whether a lack of deliberation between interdependent actors is reflected in the extent to which a specific area of law complies with benchmarks of predictability, accessibility, consistency and responsiveness or whether actors have benefited from one another's involvement.
In the choice of an area of law for a case study, several dilemmas have arisen. Choosing a national area of law, such as property law, may not make apparent whether the involvement of multiple actors is problematic. Yet opting for hybrid areas that develop functionally, such as labour law or company law, may be problematic because the development of law in these functional areas could be considered atypical for areas of traditional private law. Alternatively, in highly Europeanised areas of law, many actors coexist, which may lead to arguments that this area is similarly atypical and that the conclusions with regard to this area are not relevant for other, more traditional areas.
Arguably, choosing an area of European private law where many actors coexist provides an opportunity to look at the simultaneous development of European private law by different actors. Furthermore, the number of actors involved in the development of European private law is not likely to become smaller over time. Accordingly, European initiatives have started developing in traditional areas of private law. Eventually, mandatory rules in traditional areas such as property law may also be difficult to reconcile with the right to free movement within the European Union and they may become harmonised. Thus, national areas of private law can also look to the development of other areas of private law if and when increased international trade necessitates the development of, for example, European initiatives on the registration of immovable property in national registers.