This thesis examines the relationship between state identity and pacific blockade, a nineteenth century custom involving the stopping of traffic to a coast without a declaration of war. Drawing on via median constructivism, diplomatic history and international law’s histories, it attempts to explain how pacific blockade emerged despite contradicting contemporary international law, what significance it had for blockading states, and how it could disappear without an explicit rejection. The thesis argues that this practice acquires legitimacy for British decision-makers by performing multiple, conflicting identities in the Ottoman Empire and Latin America. It links pacific blockade to cultural and material hierarchies that legitimized ignoring blockaded states’ interpretations of events. When the institutional and normative context of the practice changes, the thesis argues that pacific blockade loses its legitimacy to states and international law. Thus it provides an example of an exclusive norm disappearing despite its performance of multiple state identities.