Despite the vast literature on policy implementation, systematic cross‐national research focusing on implementers’ performance regarding different policy issues is still in its infancy. The European Union policies are conducive to examining this relationship in a comparative setting, as the EU member states need to implement various EU directives both legally and in practice. In this study, a first attempt is made to analyse the relationship between legal conformity and practical implementation and the conditions for practical deviations in 27 member states across issues from four policy areas (Internal Market, Environment, Justice and Home Affairs and Social Policy). In line with existing approaches to EU compliance, it is expected that the policy preferences of domestic political elites (‘enforcement’) affect their incentives to ‘decouple’ practical from legal compliance. Instead, administrative and institutional capacities (‘management’) and societal constraints (‘legitimacy’) are likely to limit the ability of policy makers to exert control over the implementation process. The findings suggest that practical deviations arise from policy makers’ inability to steer the implementation process, regardless of their predispositions towards internationally agreed policies. The results have strong implications for the effective application of international rules in domestic settings, as they illustrate that political support for the implementation of ‘external’ policy does not ensure effective implementation in practice.

Whereas quantitative studies show that the 'new' EU entrants from Central and Eastern Europe (CEE) are the forerunners in the transposition of EU directives, case studies indicate the existence of a gap between legal and practical compliance. This study aims to reconcile these divergent findings by comparing member states' performance regarding different compliance aspects: delayed transposition; legal and practical conformity. We address the following questions: Do we observe systematic variation in compliance (a) between different EU member states, (b) between different forms of compliance? To what extent do preference-and capacity-based factors explain differences in implementation between the EU-15 and the EU-10 states? Our analysis shows that the CEE member states are generally more efficient in transposing the EU rules than their Western counterparts. In addition and with the exception of social policy directives, the CEE member states do not lag behind the EU-15 countries with respect to practical implementation.

Whereas most research focuses on non‐compliant implementation, we lack understanding of implementers' incentives and abilities to outperform national legislation. This study investigates a largely under‐researched question: to what extent practical implementation exceeds levels of legislative compliance with EU requirements? To explain this phenomenon, we focus on the responsiveness of implementing actors to external (participation in transnational networks) and domestic pressures (national societal attitudes) for compliance with EU requirements and the availability of additional expertise at the implementation stage (bottom‐up). Moreover, implementing actors are unlikely to respond in the same way to different types of national legislative problems (top‐down). The findings suggest that implementers often outperform the transposition of EU laws. Practical outperformance depends on the level of societal support for external policies and is a response to incomplete or ambiguous domestic formal rules.