This book provides a genealogy of the concept of ‘prool’ in government. It examines the functions that different prools play in the contemporary world, and how they act as devices which regulate delicate and strategic fields of politics and society. The book opens by assessing the historical origins of the word ‘prool’, proposes a typology of prools, and highlights the three main actions of these devices: formalising, standardising, and certifying. It then stresses the ways in which prools are employed as governing devices, their use as policy instruments, and their role within capitalism. The book concludes by analysing prool as a method for managing various aspects of social life. The politics of prools and the dilemmas they present, especially within crisis and emergency scenarios, are also discussed. The book will appeal to scholars and students of public policy, sociology, political philosophy and the theory of law.