Theorising the Constitutional Status of Customary International Law in Nigerian Public Law: Judicial Reception and Transformative Potential

The constitutional status of customary international law in Nigerian domestic courts remains theoretically unsettled, with the 1999 Constitution's silence on the incorporation of customary international law leaving courts to develop reception doctrines without a clear constitutional mandate. The potential for customary international law norms on jus cogens violations, environmental damage, and indigenous rights to serve as directly applicable legal standards in Nigerian courts represents an undertheorised dimension of Nigerian public law with significant transformative potential. This study theorises the constitutional status of customary international law in Nigerian public law, examining the judicial reception history of custom in Nigerian courts, the theoretical bases for direct application, and the conditions under which customary international law can supplement constitutional rights protections. The methodology combines a systematic doctrinal analysis of all identified Nigerian court decisions referencing customary international law from 1960 to 2023, with comparative theoretical analysis of customary international law reception in the United Kingdom, South Africa, and India. The Transformation Doctrine, Adoption Doctrine, and Monist Incorporation Theory provide the theoretical counterpoints for original framework development. International Law Scholarly Theories from Brownlie, Cassese, and Chimni provide the international law theoretical foundations. The study's original contribution is a Customary International Law Reception Theory for Nigerian Public Law that clarifies the constitutional basis and judicial conditions for domestic application of customary international norms. Findings provide a judicial practice guide and a proposed Supreme Court Practice Statement on custom. Keywords: customary international law, judicial reception, constitutional law, international law, Nigeria.