The constitutional role of the German Bundestag in the conclusion of mixed agreements by the EU and its Member States has been an open question for decades. This has been due to a certain pragmatism in dealing with these issues. Growing tensions between Government and Parliament, however, especially concerning controversial treaties like TTIP, CETA or the Economic Partnership Agreements with Western African States, press for an answer at last. The participation prior to the actual conclusion of the treaty is determined by Article 23, of the Grundgesetz (GG). Mixed Agreements are »matters concerning the European Union« in the sense of its para. 2; the Federal Government has to keep the Bundestag informed in such matters, »comprehensively and at the earliest possible time.« As far as they fall within the competences of the EU, mixed agreements also qualify as »legislative acts of the European Union« in the sense of para. 3. Insofar Article 23 GG obliges the Federal Government to give the Bundestag »an opportunity to state its position« which than has to be »taken into account« during the negotiations in the Council. According to Article 59 para. 2 GG, international treaties concluded by the Federation require the consent of the Bundestag and Bundesrat in the form of a federal statute in two cases: if they »regulate the political relations« of the Federation or if they relate to subjects of federal legislation. The traditional, restrictive understanding of »political relations« as referring only to the existence and security of the German State, is outdated. Only those treaties should be excepted that are »unpolitical«, i.e. mere »executive agreements« (cf. Article 59 para. 2, cl. 2). Based on such an up-to-date interpretation of the »political«, many mixed agreements will need parliamentary consent already because of those provisions alone which fall within the Member States' competences. It does not follow automatically that in all other cases there is no need for parliamentary consent. A model based on a separation of the spheres of competence does indeed have regard to the legitimising role of the European Parliament (cf. Article 218 para. 6 TFEU); applied strictly, however, it risks of missing the specific qualities of the EU system of competences, especially in the case of mixed agreements. Here, competences are not so much relevant for a demarcation of political spheres, but as a basis for political empowerment. In practice, any clear demarcation is deliberately avoided. Mixed agreements only rarely contain a declaration on competences, thus leading to a joint responsibility and liability of the EU and its Member States under international law. Therefore, an adequate model has to introduce some correctives to the basic idea of a separation of competences. Interpreting Article 59 para. 2, cl. 1 GG in the light of the Bundestag's »responsibility for integration« (Integrationsverantwortung) as derived from Article 23 GG, all mixed agreements need parliamentary consent if they are of a particular political importance. Indicators might be that they either concern fundamental questions of membership in an international organisation or for the relations to third states; if they further reduce the Member State's scope of action in areas where competences have already been transferred to the EU to a large extent; if they impact individual rights; if they are subject to an intense and controversial public debate. Conforming to German state practice, parliamentary consent does not only cover those parts of the agreement falling within national competences, but they cover the treaty as a whole.