Mapping the scope for flexible implementation in EU directives

Studies of EU implementation and customization have revealed wide differences among member states in the way EU legislation is being implemented. This type of diversity is often allowed (or even actively facilitated) by EU law. To that end, EU legislation includes different types of flexibility, for instance by providing for minimum harmonization, by allowing member states further to specify certain provisions, by offering a choice between options or by allowing member states to expand or restrict the scope of the legislation. These types of flexible implementation may offer a way to cope with diversity among member states. In that sense, they may serve as an alternative or complement to forms of differentiated integration, in which some member states are excluded from parts of EU law altogether. The room for flexible implementation by member states is determined by the limits set in EU legislation. This paper sets out to map systematically how much flexibility EU legislation offers. Based on an original dataset of 163 hand-coded directives adopted in all areas of EU policy-making in the period 2006-2015, it analyses the occurrence and extent of provisions allowing for flexible implementation, as well as associated constraints on member states. In addition, it links the levels and types of discretion to a number of key theoretical variables, in order to obtain a better understanding of what determines the scope for flexible implementation offered in directives. By taking EU legislation as its starting point, the paper offers a valuable complement to studies that look at the way member states implement EU law. Moreover, it contributes to existing studies of discretion in EU law by the combination of a detailed analysis of types of discretion and a large number of cases in the dataset. This allows for a more fine-grained and systematic assessment of the way discretion is incorporated into EU law.