a constitutional analysis.

What type of political association is the European Union? From the start of the European integration process, this question has puzzled scholars. Many different answers have been offered, but in the absence of an agreed response, most scholars implicitly avoid the issue by suggesting that the European Union is ‘sui generis’. In contrast, this thesis maintains that the European Union is a federation (Bund): a political union of states founded on a federal treaty-constitution that does not constitute a new federal state. The thesis maintains, further, that the federation is a discrete form of political association on a par with, though differentiated from, the empire and the state. The thesis aims to make three contributions. First, to contribute to the constitutional theory of the European Union by solving the mystery of its political form. Second, to contribute to the constitutional theory of the federation through an in-depth case study of the European Union as a federal union of states. Third, to contribute to both European Union studies and federalism studies by showing, first, how some of the most profound constitutional questions of the contemporary European Union raised by the rise of authoritarianism in Poland and Hungary and the Eurozone crisis can be properly understood on the basis of the constitutional theory of the federation. Second, by demonstrating how these contemporary issues shed light on the most difficult question for the constitutional theory of the federation: whether, to what extent and under what circumstances the Union has authority to intervene in the internal constitutional affairs of its Member States.