Proportionality as a Global Standard of Constitutional Review: Convergence and Divergence

Abstract

This review paper examines the global diffusion of proportionality as a standard of constitutional review, analyzing both its convergent doctrinal vocabulary and the divergent practices through which that vocabulary is operationalized. It first traces the historical origins of proportionality in German administrative and constitutional jurisprudence and its subsequent migration to European, common law, and Global South jurisdictions. The paper then identifies a convergent core: a shared set of four functional categories-legitimate aim, suitability, necessity, and balancing-together with shared judicial practices of justification and rights discourse. Yet significant divergence persists in the intensity of review, the margin of appreciation afforded to legislative choices, the order and weight of the stages, the effect of failure at each stage, and the application to socio-economic rights and positive obligations. Drawing on a core sample of six systems-Germany, Canada, the United Kingdom, South Africa, the European Court of Human Rights, and Brazil-the paper highlights theoretical critiques concerning incommensurability and rationality, as well as institutional and democratic legitimacy concerns. It further considers emerging adaptations in supranational and hybrid regimes and potential alternative standards. The paper concludes that while proportionality has become a lingua franca of rights adjudication, its global standardization is incomplete and contested, marked by a dynamic interplay of convergence and divergence. This duality has profound implications for comparative constitutional theory and the future of rights-based judicial review.