The sources of EU law and their relationships: Lessons for the field of taxation

The thesis provides a systematic analysis of the relationship of the various sources of EU law with the aim of deducing, primarily, from the Union Court's case law rules and principles governing the interactions, conflicts and overlaps of such sources and advocate for their consistent application. The thesis is divided into three parts. First, the general features of the EU's normative order are described. Second, the relationship of primary law, specifically, the TFEU's free movement provisions and secondary law is examined. It is concluded that the Union Courts use a very low standard for substantively scrutinizing Union legislation which weakens the hierarchy between primary law and secondary law. Third, the interaction between the TFEU's free movement provisions and the State aid rules is analysed. A comparison is provided of the methods of analysis applied by the Union Courts when they test the compatibility of national tax measures with the free movement provisions, on the one hand, and the State aid rules, on the other. The analysis shows a gradual but clear convergence of these two methods which leads to overlaps between the scopes of these two regimes. It is suggested that the State aid rules should be considered as general rules in relation to the more specific free movement provisions.
The relationships of various sources of EU law is examined in the thesis with a focus on the field of taxation the specific characteristics of which make it especially a suitable context to demonstrate the multiple aspects of these relationships.