In the period spanning nearly a decade from the beginning of the financial crisis to the present, the constitutional state and state system in Europe has been affected by a series of challenges to its authority and legitimacy. With regard to the European Union, these challenges are fundamental in that they go to the very existence of the project and to the values it professes to be founded on. They seem increasingly interconnected to the EU and the trajectory of integration rather than merely external to it. For the moment, the EU remains relatively resilient; outside of the UK, appetite for ending the experiment mostly inhabits the political fringes, although even in core countries, anti-European pressures are mounting and Eurosceptic parties are on the ascendency. What is clear is that the challenges to the current system go as much to the legitimacy of domestic regimes and their political authority as to the EU itself, not least from the fragmentary pressures on the state from below in the context of subnational claims to autonomy. In short, the crisis of authority is not merely of the EU but of the regional state system and the governing order in Europe.