1. Enforcement of EU Law
Supremacy

2. How to solve conflicts in a federal system of law
Hierarchy of norms: supremacy of EU law over national law
European perspective: All Union law prevails over all national law
National perspective: the supremacy of EU law is relative – some national law is considered to be beyond the supremacy of EU law
Conflict with national fundamental rights (controlimiti, counter-limits in the Italian Constitutional Court doctrine)
Ultra vires control (Kompetenz-Kompetenz, BVerG)

3. Declaration 17 attached to the Lisbon Treaty
«The Conference recalls that, in accordance with well settled case law of the Court of Justice of the European Union, the Treaties and the law adopted by the Union on the basis of the Treaties have primacy over the law of Member States, under the conditions laid down by the said case law».

4. Costa/ENEL, 1964
«By contrast with ordinary international treaties, the EEC Treaty has created its own legal system which, on the entry into force of the Treaty, became an integral part of the legal systems of the Member States and which their courts are bound to apply… The integration into the laws of each Member State of provisions which derive from the Community, and more generally the terms and the spirit of the Treaty, make it impossible for the States, as a corollary, to accord precedence to a unilateral and subsequent measure over a legal system accepted by them on a basis of reciprocity. Such a measure cannot therefore be inconsistent with that legal system. The executive force of european law cannot vary from one State to another in reference to subsequent domestic laws, without jeopardizing the attainment of the objectives of the Treaties… it follows from all these observations that the law stemming from the Treaty, an independent source of law, could not, because of its special and original nature, be overridden by domestic legal provisions, however framed, without being deprived of its character as European law and without the legal basis of the Community itself being called into question».

5. Disapplication of conflicting national law – Simmenthal, 1978
«In accordance with the principle of precedence of European law, the relationship between provisions of the Treaty and directly applicable measures of the institutions on the one hand and the national law on the Member States on the other is such that those provisions and measures not only by their entry into force render automatically inapplicable any conflicting provisions of current national law but – in so far as they are an integral part of, and take precedence in, the legal order applicable in the territory of each of the Member States – also preclude the valid adoption of new legislative measures to the extent to which they would be incompatible with European provisions».

6. National challenges: Fundamental rights and counter-limits theory
In Internationale Handelsgesellschaft (1970, the Court said that the validity of European measures can only be judged in the light of European law (absolute supremacy). The case moved back to the German Constitutional Court, which expressed its theory of relative supremacy. «The part of the Constitution dealing with fundamental rights is an inalienable feature of the valid Constitution of the Federal Republic of Germany and one which forms part of the constitutional structure of the Constitution». The Court affirmed in particular that so long as the European legal order had not developed an adequate standard of fundamental rights, the German Constitutional Court would disapply European law thet conflicted with the fundamental rights guaranteed in the German legal order. (Solange I, 1974).

7. Italian Constitutional Court: Frontini, 1973
Counter-limits to the limits to sovereignty accepted under article 11 Italian Constitution and the European Treaties In the improbable case of violation, by EEC institutions, of the fundamental principles of the Italian Constitution, or the fundamental rights of the human being, the judicial control of the Constitutional Court would be always assured. This judicial control would have as object the compatibility of the Treaty with said fundamental principles.

8. National challenges: Kompetenz-Kompetenz and competence limits (the judicial control on ultra vires acts
ECJ, Foto-Frost, 1987: national courts cannot disapply nor invalidate European law

9. National challenges: Kompetenz-Kompetenz and competence limits (the judicial control on ultra vires acts
BVerGE, MaastrichtUrteil, 1994: «The Federal Constitutional Court will review legal instruments of European institutions and agencies to see whether they remain within the limits of the sovereign rights conferred on them or transgress them». EU law adopted ultra vires could be disapplied by the German Constitutional Court.

10. National challenges: Kompetenz-Kompetenz and competence limits (the judicial control on ultra vires acts
BVerGE, LissabonUrteil, 2010: As long as, and insofar as, the principle of conferral is adhered to in an association of sovereign states with clear elements of executive and governmental co-operation, the legitimation provided by national parliaments and governments complemented and sustained by the directly elected European Parliament is sufficient in principle».