This book offers a comprehensive reconstruction of proportionality in constitutional law, tracing its trajectory from its origins in Prussian administrative law and German constitutional adjudication to its contemporary application across diverse legal systems. Against the conventional approaches that equate proportionality with the weighing of competing values, it argues that this test was originally conceived as a dogmatic instrument for the protection of rights, not as a balancing technique. Through a detailed comparative analysis of the German and Brazilian experiences, the book reconstructs how proportionality gradually shifted from a strict limit on state power to an open formula of judicial discretion, and proposes a coherent model to restore its normative function. The book critically re-examines the philosophical and theoretical assumptions that transformed proportionality into an indeterminate balancing exercise and reconstructs it as a structured dogmatic test defined by constitutional parameters of protection. Engaging with authors such as Robert Alexy, Bernhard Schlink and Ralf Poscher, it maps how proportionality became the dominant method of constitutional adjudication and how that dominance produced both methodological uncertainty and jurisprudential uniformity. Finally, it proposes a theoretical framework that distinguishes proportionality in the singular, as a general abstraction, from proportionalities in the plural, calibrated to the specificities of each right, context and mode of judicial review. This plural and context-sensitive approach restores the analytical precision that contemporary constitutional law often lacks. By combining historical analysis, comparative dogmatics and legal theory, the study contributes to current debates on the legitimacy and limits of judicial review, the boundaries of fundamental rights and the crisis of constitutional interpretation in modern democracies.

Lucas Catib de Laurentiis is Professor of Public Law and General Theory of the State at the Faculdade de Direito de São Bernardo do Campo (FDSBC) and Affiliated Researcher at the São Paulo Law School of Fundação Getulio Vargas (FGV Direito SP) and at the School of Law of the University of Minho (Portugal). He holds a doctorate and a master's degree in Constitutional Law from the University of São Paulo (USP). During his doctoral studies, he was a visiting researcher at the Albert-Ludwigs-Universität Freiburg, with funding from CAPES. He also held a postdoctoral fellowship at the Max Planck Institute for the Study of Crime, Security and Law in Freiburg, Germany, and is currently principal investigator in research projects funded by FAPESP and CNPq.