The transnational use of evidence in tax proceedings and criminal tax evasion proceedings with additional change of the kind of the proceeding (tax -> criminal, criminal -> tax)
I describe the constitutional standard within the European Union concerning inadmissible evidence (exclusionary rule) and the fruit of the poisonous tree doctrine and accidental discovery of evidence in case of the usage of information. I refer to German, Austrian and European law. The scope and effect of constitutional principles, fundamental rights, fiscal secret and the right against self-incrimination is described for transnational use of evidence or change of the kind of the proceeding. The mutual legal assistance in tax and in criminal matters is examined upon barriers established by the rules of mutual assistance and upon barriers in the international law itself (double tax treaties; EU mutual tax administrative assistance in the EU according to the EU rule and the national laws; EU capital gains directive, mutual legal assistance in criminal matters of the council of Europe, mutual legal assistance in criminal matters of the member states of the European union, protocol to the mutual legal assistance in criminal matters of the member states of the European union, German and Austrian law for international legal mutual assistance in criminal matters, etc.). The thesis describes structural barriers in usage of evidence in the case of falling apart of the collecting and the utilizing legal system. The usability of the Liechtenstein-DVD (DVD with tax datas illegally bought by the german secret service) as evidence is answered according to transnational aspects of law.