The Constitutional Dimensions of Private Law: Horizontal Application of Fundamental Rights in Nigerian Private Litigation

The question of whether constitutional fundamental rights apply horizontally between private parties in Nigeria, compelling courts to interpret and develop private law in conformity with constitutional values, represents one of the most profound and theoretically underdeveloped questions at the intersection of public and private law. This study examines the constitutional dimensions of private law in Nigeria, developing an original theoretical framework for the horizontal application of fundamental rights in private litigation, drawing on the Dworkinian theory of rights as trumps, South African constitutional law's transformative constitutionalism, and German indirect horizontal application doctrine. Using a multi-level theoretical and empirical methodology, the research analyses 60 Nigerian cases from 2015 to 2024 in which fundamental rights arguments were raised in private law contexts including defamation, property, employment, and family disputes, supplemented by interviews with 25 constitutional law scholars and practitioners in Abuja and Lagos. The study maps the current state of horizontal application in Nigerian law, identifies cases where constitutional values have influenced private law outcomes without explicit doctrinal articulation, and constructs a theoretical model for principled constitutional influence on private law development. This research constitutes a genuinely original contribution to Nigerian constitutional law and private law scholarship by providing the first comprehensive theoretical treatment of the constitutional dimensions of private law. Recommendations include judicial guidelines on fundamental rights in private litigation, academic curriculum reform, and a landmark Supreme Court reference on horizontal effect. Keywords: fundamental rights, horizontal application, constitutional law, private law, transformative constitutionalism