Primacy, that is the precedence EU law takes over any national laws in cases of conflict, is one of the most fundamental aspects of EU law. The primacy doctrine elaborated in Costa/ENEL by the Court has not always been fully endorsed by various constitutional courts in the Member States (the Solange judgment of the Bundesverfassungsgericht is the most well known example). However, to date national courts have always applied the doctrine, albeit with reservations.
That has ended with a recent ruling by the Czech Constitutional Court. In a case concerning an alleged discrimanatory pension scheme in the Czech republic that resulted from the dissolvation of Czechoslovakia, it held that the Court in its judgment in Case C-399/09 Landtová acted ultra vires and subsequently gave Czech national law precedence over EU law. This is a quote from the press release of the Czech Constitutional Court:
In its judgement, the Constitutional Court first expressed its view on the conclusions following from the judgement of the Court of Justice of the EU. In the introduction, the Constitutional Court summarized its previous case-law concerning the relationship between national and European law and above all emphasised the thesis (which follows also from the doctrine of the Federal Constitutional Court of Germany) under which constitutional courts maintain their role of supreme guardians of constitutionality even in the realms of the EU and even against potential excesses on the side of EU bodies. In this respect, the Constitutional Court believes that a European regulation which governs co-ordination of pension system among the member states may not be applied to an entirely specific situation of a dissolution of the Czechoslovak federation and to consequences stemming thereof. The Constitutional Court wishes to emphasise that the period of employment for an employer based in the territory of today´s Slovak Republic cannot be considered a period of employment in abroad (besides, social security had been subject to federal competence in the entire period of existence of the Czechoslovak federation). Therefore, the Constitutional Court expressed the view that matters of social security and claims following from them did not in the case of so-called Slovak pensions contain a foreign element which is a prerequisite for the application of the co-ordination regulation. This issue cannot be compared to consideration of social security claims with respect to acknowledgement of periods obtained in different states, whilst it is the issue of consequences of dissolution of the Czechoslovak federation and of division of costs on social security between the successor states.