Abstract
<jats:title>Abstract</jats:title> <jats:p>This chapter examines the conditions under which international legal change succeeds or fails outside of contexts of treaty-making. Using descriptive statistics and regression analysis, the chapter tests key explanatory variables on a dataset coded on the basis of close readings of twenty-five case studies. It evaluates competing accounts of norm change—ranging from statist explanations to those focusing on norm characteristics—and finds the strongest support for an authority-based institutionalist account. More specifically, the chapter finds that traditional expectations centred on state support, great-power backing, and norm adjacency are overstated. While broad state opposition can constrain change, neither major power support nor norm adjacency significantly predicts success. Against this backdrop, state opposition appears more influential in blocking, diluting, or reversing legal change than in constructing it. By contrast, and crucially for understanding successful change episodes, the presence of support from focal authorities—an institution or body with recognized authority in a given field—emerges as the most consistent factor associated with successful change efforts. These authorities are crucial for incremental change processes; they help mitigate resistance against change and consolidate new legal understandings, even in the face of state opposition. Additional findings highlight that change initiatives around permissive norms—norms that do not require broad state consensus to be implemented—are more likely to succeed, whereas the existence of rival norms tends to undercut the likelihood of success. The chapter concludes that international legal change is shaped less by material dominance and more by authority structures and the types of norms at stake. It invites scholars to rethink the centrality of states and recognize the importance of institutional authority in facilitating legal transformation.</jats:p>