Summary
The departure of a member state from the European Union seems like a failure of the Union. But the right of a member state to exit can also be a part of the legitimacy of the EU. This brief explains that paradox. It also asks at what point exit becomes so difficult that it ceases to be a meaningful right that can contribute to the legitimacy of the EU. Exit is constrained by feasibility, and by the obligations a withdrawing state has accumulated throughout its membership. Brexit deepens our understanding of those constraints.