Recent years have seen a new, by now almost normalized, openness towards empirical,interdisciplinary approaches within international law scholarship; in part driven by research conducted within the Nordics. Scholarship that bridges International Law and International Relations has been a key example, promising new insights on how power dynamics shape international law, and how international law in turn constitutes global order. However, interdisciplinary work combining both disciplines has also been met with critique, including accusations of disciplinary hegemony, a priori theorising, and not accounting for international law’s normativity. This article argues that practice theory provides one possible way to address these challenges. Focusing on day-to-day legal practices, especially at the intersections of legal regimes, we identify three examples of particularly promising research avenues: state responses to international legal developments; international lawyers navigating overlapping communities of practice; and data-driven approaches for understanding how legal interpretations are negotiated across different groups of practitioners. All
three avenues offer important insights on how international law develops and changes in practice.