This Time it's Different: Legitimacy and the Limits of Differentiation after Brexit

British political debate since the EU referendum has hinged on what type of Brexit to pursue: hard or soft. Yet, unlike in instances of treaty rejection, the EU made no counter offer to avoid a breakdown in relations that would follow the hardest of exits. This remarkable unity in not discounting the possibility of a hard Brexit demonstrates that UK withdrawal is very distinct from previous wrangles over EU reform. Drawing on the work of Kissinger, this article argues Brexit is a revolutionary act that denies the legitimacy of the EU order. Hence this process does not conform to other episodes of differentiation. When Westminster sought opt-outs, it did not reject the core principles of integration. By not seeking to oppose a hard Brexit, Brussels has forced the UK government to find a new legitimizing principle to govern EU-UK relations, transferring the burden of adjustment to London.