extent this must be upheld for those constellations. In the case at hand, however, what is at issue is not the validity or applicability of EU law, but the proper application of fully harmonised EU law in light of the fundamental rights of the Charter, which must be specified in the individual case. The constitutional complaint concerns a decision of a German ordinary court, which must be reviewed as to whether, in applying EU law in line with its role, the court observed the requirements of the Charter that must be met in this case. At least in such cases, the Federal Constitutional Court cannot entirely refrain from conducting a fundamental rights review; rather, it is called upon to ensure fundamental rights protection on the basis of EU fundamental rights. 52 d) The Federal Constitutional Court’s competence for conducting a review on the basis of EU fundamental rights follows from Art. 23(1) GG in conjunction with the provisions of the Basic Law concerning the Federal Constitutional Court’s role with regard to fundamental rights protection. In conducting a review on the basis of the fundamental rights of the Charter in constitutional complaint proceedings pursuant to Art. 93(1) no. 4a GG where the scope of application of fully harmonised EU law is concerned, the Federal Constitutional Court exercises its responsibility with regard to European integration (Integrationsverantwortung) under Art. 23(1) first sentence GG, which is in line with its role to provide comprehensive fundamental rights protection vis-à-vis German state authority. 53 aa) According to Art. 23(1) GG, the Federal Republic of Germany participates in the realisation of a united Europe and may transfer sovereign powers to the EU to that end. Together with the other Member States, Germany has transferred powers to the EU, by way of the Treaties, to allow the EU to adopt its own legal acts. The Member States have worked together to create the Charter of Fundamental Rights, which stands alongside EU law and the powers transferred to the EU. On this basis, the German acts of approval to the EU Treaties open the German legal order to EU law, recognising EU legal acts as directly applicable at the domestic level. Thus, the German legal order also respects, in principle, EU law’s claim to precedence of application vis-à-vis domestic law, including German constitutional law (cf. BVerfGE 129, 78 <100>; 142, 123 <187 para. 118> with further references). 54 The Basic Law’s openness to EU law under Art. 23(1) GG does not relieve the German state of its responsibility in matters for which competences have been transferred to the EU; to the contrary, this provision provides for the participation of Germany in developing and giving effect to European integration. This presupposes a close interlinking of the legislative levels, in accordance with the substance of the Treaties. These provide that the implementation of EU law falls only to a limited extent to EU institutions and to a large extent to the Member States. Thus, effect is given to EU law at the domestic level in Germany in accordance, in principle, with the requirements concerning the organisation of the state as set out in the Basic Law. It provides that all state organs have a responsibility with regard to European integra- 55 11/36