In the literature on secession, there are two broad positions. On the one hand, some think there is a direct or primary right to secede. That is, groups always have a right to choose to leave an existing state provided that they, as a group, meet some criteria. The usual criteria are (a) being a ‘people’ with a shared set of cultural traditions or heritage distinct from those of the wider nation of which they are presently a part or (b) democratic election (e.g., by majority vote). On the other hand, some think that there is ‘only’ a default or secondary right to secede. Groups have this right only if their present government mistreats them in certain ways. Here, the right to secede is like the right to revolution. It is ‘activated’ if governments abuse citizens’ most basic rights, by, for example, torturing them or imprisoning them for their political beliefs.
My view is that secession cannot be a primary right. It seems to me too permissive to allow groups such broad discretion on leaving an existing state. In certain cases, this would permit patently unjust possibilities, such as the white South Africans responding to the end of Apartheid by voting to form an independent nation. More generally, we surely think that there are limits on what a people can choose. People do not have a right to disenfranchise part of the existing population of a nation on matters that concern them all, so why should they have a right to vote for border changes that would have the same effect?
Thus, my sense is that any right to secede from a political association must exist only on the condition that the political association surpasses a certain threshold of injustice. If this line of reasoning is applied to the case of the EU, the UK clearly does not have a right to vote on its membership.
I guess that there are two possible objections to this view. First, it might be argued that the EU is beyond a threshold of injustice. I find it difficult to see how such a position could be substantiated. Indeed, given some of its decisions, such as voting rights for prisoners, I am inclined to think it propagates less injustice than the UK. But, at any rate, it clearly does not fall foul of grave human rights abuse or anything that would permit rebellion. Second, it might be argued that there is a difference between seceding from a state and seceding from a supranational organisation. I cannot say that I disagree with this thought, but I do not think that the difference will be sufficient to challenge my central claim. Whatever the differences, the EU is a political association with binding rules of membership subject to demands of justice. The parallels are not so far from much decentralised federal structures like Switzerland. So, just as I believe the people of Zug do not have a right to choose independence from the Confœderatio, I do not think the UK should be granted a referendum on European Union membership.