One of the principal constitutional functions of the European Court of Justice (ECJ) is to secure legitimacy of the European Union (EU) system of governance by protecting the fundamental values on which this system is said to rest. This role of the ECJ – as a guardian of democracy, fundamental rights and the rule of law – is complicated by the multi-layered nature of the EU's sources of legal authority: the EU institutions and the law-making bodies of Member States (MSs), and by the heavy reliance on the co-operation of National Courts (NCs) in building up and maintaining the EU's legal system. I focus on providing an overview of selected problems that are directly related to the ECJ's legitimising role, and I will do so from the perspective of the ECJ's constitutional politics.
First, I will consider whether the alleged prioritising – by the ECJ – of the principles of integrity of the EU legal system and economic regulations over constitutional values – such as fundamental rights and democracy – amounts to an ideological project that undermines the legitimacy of the EU law. I will focus on instances where the ECJ failed to recognise concerns of the NCs related to the standard of protection of these values in the EU law for the sake of protecting its own authority and the uniformity of the EU law. Historically, these concerns were most famously identified in the so-called ‘supremacy’ challenges, but there was also a string of other cases where the protection of market freedoms clashed with fundamental rights and other constitutional principles. Th is period of the ECJ jurisprudence took a more rights-friendly turn in cases such as Omega and Schmidberger. The more recent NCs challenges yet again put the ECJ under pressure, this time because of its reluctance to recognise the higher standards of fundamental rights protection related to criminal trials in national constitutions over those existing in the EU law. The string of the European Arrest Warrant (EAW) cases seems to suggest that the ECJ yet again entered a path of prioritising the supremacy of the EU law over substantive constitutional objectives.