This monograph utilises the case of cross-border bank crisis management in ASEAN to illustrate the challenges posed by the financial trilemma—the inherent tension between financial stability, national sovereignty, and financial integration. It provides an in-depth analysis of both legal and non-legal mechanisms employed by ASEAN member states and argues that existing frameworks remain insufficient for withstanding future financial crises. Structured across six chapters, the monograph covers key areas including the role of law in the financial trilemma, cross-border banking supervision, bank resolution regimes, deposit insurance systems, and public assistance and fiscal backstops. It concludes with seven policy recommendations aimed at guiding ASEAN toward a more robust framework for mitigating systemic risk and minimising the financial trilemma. The monograph also examines the European Union’s legal tools for cross-border bank crisis management, offering comparative insights into both the strengths and limitations of legal mechanisms in practice.