This article examines the relationship between solidarity and territorial boundaries, both of which are critical focal points in relation to the process of European integration. With that focus on boundaries and solidarity, the article will take a fresh look at cross-border movement of patients by conceptualising the field in a more abstract and theoretical manner which aims to be of value in relation to welfare systems in general. In particular, the article will examine the role of free movement and human rights as instruments for overcoming territorial boundaries. The degree of impact these rights have on boundaries and consequently on solidarity, by virtue of the authority they convey, is largely determined by the underlying principles, namely efficiency and dignity, which constitute the normative basis of these rights. One of the defining characteristics of the Westphalian system has been that 'the modern notion of "territory" is inextricably linked to the rights of jurisdictional authority over a territorial or geographical domain, and so is a profoundly political notion'. 2 A pivotal aim of the single market is to call this established system into question and create another 'single space'. 3 This process has both a territorial and a membership dimension. To what extent the 'territorial masters [have been] losing control of their own borders' as a consequence of European integration remains a contested question. 4 I am interested in this question with regard to solidarity and will use cross-border movement of patients, which has been linked closely to the principle of territoriality, as a paradigmatic example. 5