This chapter examines the application of the prohibition of abuse of rights under the EU fundamental freedoms in tax matters with a focus on artificial transactions. When analysing the case law of the Court of Justice the concept of artificiality represents one of the few firm points of the abuse test. However, although this principle appears somewhat self-evident, the methods by which it is enforced leave some doubt, as the Court’s approach does not appear to be entirely consistent across the various areas of tax law (in particular harmonized and non-harmonized areas). In this respect, the lack of certainty is particularly evident when the Court attempts to assess the compatibility of a taxpayer's conduct with the objectives of the EU's fundamental freedoms in direct tax cases.