It seems a common view in European political practice that the state’s broad sovereign right to exclude noncitizens from its territory at the border releases it from any special obligations toward irregular immigrants, who reside on its territory without its consent. In this article the author reflects on the validity of that view. In so doing, she begins with the common-sense doctrine that special obligations are generated by significant interactions. On conventional accounts of special obligations, a significant interaction between the state and immigrants arises if and only if (a) the state enters into a formal relationship with them, by issuing, for instance, a residence permit, or (b) the state can be blamed or held liable for harm that they have suffered. Contrary to this account, the author argues that the state inevitably interacts with immigrants through the process of enforcing its borders. This presumes a relational account of borders as a space of interaction rather than as a fixed line of separation that divides a domestic realm of state action from an international realm. In the process of enforcing its borders, the state necessarily interacts with immigrant in this space, and thereby assumes special obligations to them.