IOC Divestment and Historical Environmental Liability in Nigeria: Can International Oil Companies Escape Legacy Pollution Obligations after Asset Transfer?

Between 2024 and 2025, every major international oil company (IOC) that had operated onshore in Nigeria for half a century walked away. Shell completed the sale of the Shell Petroleum Development Company of Nigeria Limited (SPDC) to the Renaissance Africa Energy consortium in March 2025; ExxonMobil transferred Mobil Producing Nigeria Unlimited to Seplat Energy; Eni divested the Nigerian Agip Oil Company to Oando; Equinor sold to Project Odinmin Investments; and TotalEnergies signed a USD 860 million agreement with Chappal Energies. Behind these transactions lies a deeper, unsettled legal question that this article confronts directly: Does the assignment of an oil mining lease (OML) extinguish the assignor's liability for historical environmental damage that pre-dates the transfer? Working from the text of the Petroleum Industry Act 2021 (PIA), the Upstream Petroleum Environmental Regulations 2022 (UPER), the Oil Pipelines Act 1956, common-law tort doctrine, and the most recent rulings of Nigerian and English courts, including the landmark Alame v Shell Plc [2025] EWHC 1539 (KB), this article argues that legacy environmental liability is not extinguished by divestment. It is, however, badly under-regulated, and the gap between the polluter-pays principle and the contractual architecture of these sales is now the central vulnerability of Nigeria's environmental governance framework.