This article develops an institutional understanding of borders. Drawing on constitutive constructivism and theories of practical communication we argue that bordering as a process is a form of sorting through the imposition of status-functions on people and things, which alters the perception of that thing by setting it within a web of normative claims, teleologies and assumptions. Studying any border, therefore, extends to include the rule structure that constitutes it as well as the sources of that structure’s legitimacy. Furthermore, rule structures are both restrictive and facilitative and importantly they overlap while retaining different sources of legitimacy: actors bring different constitutive perspectives on the border depending on the particular rule structure they are drawing on in order to make legitimate claims about what that border produces. This recognition sensitizes analysis to the interplay between different sense-making regimes and their authoritative underpinnings. Methodologically it points researchers towards the practical and discursive methods actors use when making arguments about what a particular border can and does do