Much Ado about Pluto? The 'Unity of the Legal Order of the European Union' Revisited

The European Union is commonly described as a temple-like construction resting upon three pillars. Whereas the first pillar, Community law, constitutes a "new legal order" of supranational character, the second and third pillar are considered to be of intergovernmental kind, i.e. traditional public international law. However, some commentators have advocated a more integrated view, claiming the "unity of the legal order of the European Union". The more recent case-law of the European courts has increasingly to deal with the relationship between the pillars as well as the legal nature of Union law. The present paper analyses this case-law and takes the opportunity to revisit the "unity thesis" as put forward in learned writings, the overall conclusion is that the claim of unity is poorly suited to solve interpretative questions that concern the aforementioned questions.