The The British decision to leave the EU in the referendum held on the 23rd of June 2016 was made possible by article 50 in the Lisbon Treaty which allows member states to the leave the EU on their own decision. Before the Lisbon Treaty EU membership was in principle for eternity. The Brexit decision has been criticised for being based on a democratic process of poor quality due to manipulation of facts and unrealistic promises for the future. But few have questioned the democratic legitimacy of the British people unilaterally deciding on whether or not to remain in the EU. In this article, as part of a general argument, we will do exactly that. We argue that withdrawal from the EU by any member state cannot be defended from the perspective of fundamental democratic principles.Withdrawal violates basic democratic commitments and undermines the possible democraticness of relationships that should be democratic. The main reason for this assessment is that EU citizens across 2 borders mutually affect each other's fundamental interests and that the EU affords citizens with a status of individual rights holders and co-rulers that would be seriously affected by unilateral withdrawal by one state. The problem is twofold. First, all those whose status is affected by the decision to withdraw are not included in making it. Second, by withdrawing from the EU, citizens will be less able to rule together democratically with regard to the issues that affect them and their status across borders. While some degree of national self-determination is called for by democratic principles, national selfdetermination cannot be absolute; that is, it cannot trump the democratic right (of other citizens) to participate in decisions that significantly affect them as individuals and as citizens; a right which is (otherwise) institutionalized by the EU. We therefore conclude that unilateral and even mutually agreed withdrawal from the EU cannot be defended on the basis of democratic principles as easily as some believe.We build our case against withdrawal from the EU on a development of the all affected principle, which says that all those affected by a decision should be included in making it. In the literature, there has been a discussion about what is the relevant understanding of being affected; what the currency of affectedness is. A central notion is that it is the affectedness of individual interests, either actually or potentially, that explains why and when people should be included in decisions. This results in the all affected interests principle. Another idea is that it is not the fact that one's interests are affected that is decisive for whether one should be included in decisions or not but that one is subjected to potential coercion. This results in the all-subjected principle. Building on the criticism of these two principles and taking inspiration from the literature on non-domination, we develop our own conception of the currency of affectedness and formulate the all affected status principle, which states that pe...