The diffusion of constitutional rights

Constitutions are commonly regarded as uniquely national products, shaped by domestic ideals and politics. This paper develops and empirically investigates a novel hypothesis, which is that constitutions are also shaped by transnational influence, or “diffusion.” Constitutional rights can diffuse through four mechanisms: coercion, competition, learning and acculturation. To analyze diffusion in the constitutional realm, we traced the historical documents of all post-WWII constitutions and documented the presence of 108 constitutional rights. With this data, we first demonstrate and analyze the rapid global spread of constitutional rights over the past six decades. We then estimate a spatial lag model to explain their adoption. Our results show that the decision of countries to adopt a right is correlated with past adoption by their former colonizer, countries with the same legal origin, the same religion, the same former colonizer, and the same aid donor. These transnational correlations are strongest when a nation adopts its first constitution.