Taking stock: a review of quantitative studies of transposition and implementation of EU law

This paper presents a literature review of all quantitative (statistical) studies of compliance with EU law. The paper introduces and makes use of a new online database http://www.eif.oeaw.ac.at/implementation/ which presents a detailed and comprehensive overview and classification of the existing quantitative research on transposition and implementation of EU directives in the member states. The study discusses and compares the different conceptualizations and operationalizations of compliance used, the list and specifications of the explanatory variables included in the models, the hypotheses proposed, and, most importantly, the findings of the literature. While the academic field has made progress in terms of assessing the scale and dimensions of the transposition failures in the EU, the causal inferences advanced in the existing literature are often weakly supported and sometimes contradictory when all studies are considered. The literature review suggests that only causal relationships that are specific for a certain time period, policy area, country, or type of legislation can be supported by empirical data, which means that broad generalizations about compliance in the EU might be impossible to uncover. The paper also suggests that decomposing the implementation process into its component stages, incorporating more rigorously the interactions between the Commission and the member states, and paying closer attention to the multilevel structure of the data in the statistical models can benefit future research on compliance in the EU.