Article 50d, paragraph 8, sentence 1 of the EStG is intended to prevent foreign income from being taxed at all, for example because it has not been properly reported abroad.  If the foreign state does not exercise its taxing rights, the German state taxes the income. However, the agreement does not provide for such a right of taxation (therefore, Article 50d, paragraph 8, first sentence, of the EStG, regardless of the agreement). The Override Treaty is contrary to international law as a violation of the treaty and entails the right of termination of the other state.  DBAs are international treaties between two states and are transposed into national tax legislation according to the German conception. These contracts can be renegotiated, terminated or amended by mutual agreement. However, if rules are unilaterally introduced into national tax law that are at odds with the regulations of each DBA, we are talking about an override treaty.  An override treaty unilaterally violates the DBA as an international treaty. The BFH  and some representatives of the literature were convinced of the unconstitutionality of the convention. In reference to Klaus Vogel , this decision was mainly justified by the principle of respect for international law of the Fundamental Law.  It should require Parliament to respect the law of the international treaty through the rule of law principle of Article 20, paragraph 3 of the GG.  Exceptionally, an override Treaty may, on an exceptional basis, be justified if necessary to avoid a violation of the fundamental principles of the Constitution.  However, it is difficult to imagine that this exemption could ever apply to double taxation conventions.
 The exception would therefore be empty in the case of tax agreements, which would mean that they would still be unconstitutional. Moris Lehner also cites the general rule of international law pacta sunt servanda as a reference. The latter, through Article 25 of the GG, has priority over the simple law and therefore does not bind the content of the agreement, but the condition of validity of the agreement.  According to pacta sunt servanda, treaty violations should be avoided, as far as possible, for example through renegotiations, and the Override Treaty is therefore an ultima ratio.  According to Lehner, if this provision were flouted, it would not lead to the unconstitutionality of the convention, but would violate a general rule of international law which, in accordance with Article 25, second sentence, of the law.  However, the breach of the agreement may in turn be justified by the constitutional requirement for fiscal justice in Article 3, paragraph 1, of the GG, in order to be able to act effectively against non-taxation.  Contrary to the few general rules of international art law.