This paper argues the case for the right of secession in Western democracies. I suggest that the winners gain more than the losers may lose. Indeed, the external effects of secession may well be positive. However, the political economy of secession is highly problematic. Ideally, the rules for secession should be set at the international level but international organisations have a vested interest in preventing secession. It is easier to establish the right of secession at the national level. The opinion of the European Union institutions that Catalonia and Scotland, after seceding, would have to reapply for EU membership has no basis in the European treaties. Nor has this question been settled in any UN agreement or Vienna Convention. There are merely practices, and they vary among international institutions. The paper concludes with suggestions on how secessions from EU member states and withdrawals of member states from the EU might be implemented.
