Horizontal by design: A systematic analysis of the application of human rights to private actors in the text of world constitutions

Abstract Legal scholarship has so far assumed that the horizontal application of constitutionally protected human rights—that is, the application of these rights to private relations, rather than purely to the state/individual relationship—is an exceptional feature of only a handful of constitutions. Through a systematic textual analysis of 195 written constitutions, the present article disproves this assumption. It shows that 76% of contemporary world constitutions envisage not only rights but also corresponding obligations for their subjects, thus justifying an understanding of rights as “horizontal by design.” The article makes two principal contributions to the academic conversation on this topic. First, it develops a typology of horizontal effect clauses within world constitutions, opening up this field of academic inquiry to constitutional design and allowing for a better understanding of how constitutions themselves speak about the application of rights to private relations. Second, the article shows that the clearest horizontal effect clauses are found in young and post-dictatorial constitutions in the Global South, and that the states that employ them are more likely to be members of regional human rights protection systems. It thus suggests that horizontal effect clauses should be considered a central feature of contemporary constitutional design with transformative aspirations.