The aim of this article is to provide a comprehensive analysis of the legal and economic effects of ECJ case law on inheritance and gift taxation. The results show that ECJ case law has had a significant influence on the development of inheritance and gift tax legislation in the European Union in terms of reducing discrimination between purely national and cross-border cases. One problem, however, is that the economic effects of the decisions are ambivalent, which leads one to question the efficacy of the Court in contributing to the establishment of an internal market.