This book offers the first comprehensive comparative study of how political polarization reshapes the role and functioning of supreme and constitutional courts. Drawing on case studies from the United States, the United Kingdom, Brazil, India, Israel, Germany, Spain, and other jurisdictions, it examines how courts are transformed when deep political and social divisions meet powerful judicial institutions. The book identifies the factors that drive courts toward partisanship, the mechanisms through which polarization alters judicial nominations, decision-making and public trust, and the broader implications for the rule of law and democratic stability. It also analyzes reform proposals aimed at reducing the political stakes surrounding courts or balancing their internal composition. Combining theoretical analysis with rich comparative materials, the book will be of interest to scholars, students, and readers seeking to understand the challenges that polarized democracies face in maintaining legitimate, independent, and effective courts.