This volume challenges conventional interpretations by demonstrating that Hans Kelsen was far from being a purely formalist thinker. Instead, it highlights his profound and enduring engagement with the threats facing constitutional democracies. The political and institutional upheavals of interwar Europe significantly influenced Kelsen's evolving vision of democracy, as this volume shows. His contributions to 20th-century democratic theory include groundbreaking insights into multiparty systems, mechanisms of moderation, minority protections, and judicial review. Furthermore, Kelsen's reflections on the crises and collapses of democracies during the 1930s remain strikingly relevant, offering valuable perspectives on contemporary challenges such as polarization and populism. This title is also available as Open Access on Cambridge Core.