In recent decades, high courts in many nations have taken on dramatic new roles in governance. This chapter notes five recurrent domains of political conflict into which high courts have been pushed, or asserted themselves, to play new roles: disputes between political incumbents and challengers, intragovernmental disputes about who governs, challenges to government stasis and maladministration, cultural and religious cleavages, and disputes about rights and equality. Exploring these judicial roles, the authors provide examples from countries around the globe. The chapter then synthesizes three factors which affect increases (and retractions) in judicial assertiveness: national institutional and political structures, contemporary political dynamics, and court-related factors. Finally, the authors identify trends which help account for the expansion of judicial roles: the spread of constitutional democracy, globalization and economic liberalization, increases in government activism, and evolving conceptions of law.