Supranational influence in EU enforcement: the ECJ and the principle of state liability

Existing research on supranational autonomy in the European Union (EU) is predominantly concerned with political and judicial agenda-setting, whereas the supranational institutions' capacity to exert independent influence in post-decisional enforcement has received more limited attention. Employing principal-agent analysis, this article explores an important component of the supranational institutions' efforts to boost EU enforcement during the last decade - the European Court of Justice's (ECJ's) establishment of the principle of state liability in conflict with the explicit wishes of national governments. This case suggests that the supranational institutions may exercise independent influence not only through agenda-setting, but also by moving the enforcement of state compliance beyond governments' original intentions when delegating supervisory competences. Tracing the attempts of member states to undo or limit the effects of the ECJ's actions, the article confirms the limits of treaty revision as a sanction, but suggests that state inaction at the national level constitutes a form of sanction which should not be neglected.