Role of a national court in implementing the European Union law and vulnerability of the principle of legal certainty

Straipsnyje analizuojamas nacionalinio teismo vaidmuo įgyvendinant Europos Sąjungos (ES) teisę, ypač atkreipiant dėmesį į Europos Sąjungos teisės viršenybės ir teisinio saugumo principų galimą koliziją bei jų suderinamumo problematiką, kuri straipsnyje atskleidžiama remiantis Europos Teisingumo Teismo (ETT) praktika. Nagrinėjamas ETT Lucchini sprendimas, šio sprendimo išvadų reikšmė res judicata principui jo ribojimo požiūriu.The article deals with the role of national court in implementation of the EU law. National court has to consider a lot of principles developed in the ECJ case-law, such as the principle of supremacy of the EU law, the principle of direct applicability of the EU law (in this regard there are certain exceptions, for instance, horizontal direct effect of directives is not possible), as well as the principles that in certain circumstances provisions of the EU law may grant rights for private persons and that under certain conditions one can rely on these rights as the ground for claims submitted before a national court, and the principle that national court is obliged to ensure supremacy of the EU law, etc. The situation when a court adopting a judgment or the already adopted administrative decision do not comply with the EU law raises important issues regarding relations between the principles of legal certainty and res judicata, on the one side, and the supremacy of the EU law, on the other side. Therefore the author of the article pays attention in particular to the problem of possible collision and compatibility between the principles of supremacy of the EU law and legal certainty and reveals this problem relying on the ECJ case-law. Legal certainty is one of a number of general principles recognised by the EU law. Relying on the ECJ case-law the author makes the conclusion that, with the exception of instances provided by the Kühne & Heitz judgment, finality of an administrative decision, which is acquired upon expiry of the reasonable time-limits for legal remedies or by exhaustion of those remedies, contributes to such legal certainty and it follows that the EU law does not require that administrative bodies be placed under an obligation, in principle, to reopen an administrative decision which has become final in that way. The ECJ Lucchini judgment is also analysed in the article as well as significance of its outcomes to the principle of res judicata in regard to the limitation of the latter. In the opinion of the author, this case does not raise the collision between legal certainty and a clear definition of res judicata, on the one side, and the supremacy and effectiveness of the EU law, on the other side. In this case the ECJ did not rely on the principles of effectiveness and equivalence, but it rather underlined the principle of supremacy and that state aid felt into the exclusive competence of the EUJ