International Investment Law and the Right to Regulate in Nigeria’s Petroleum Sector: Developing an Original Calibration Framework

This study develops an original calibration framework for balancing international investment law obligations and Nigeria's regulatory right to reform its petroleum sector in the public interest, responding to the growing conflict between Nigeria's investment treaty commitments and its sovereign policy space under the PIA 2021. Nigeria's bilateral investment treaties (BITs) with over 30 countries expose the government to investment arbitration claims whenever petroleum law reforms adversely affect investor expectations, yet maintaining complete regulatory stasis to avoid arbitration undermines democratic governance. The research employs a doctrinal and theoretical legal methodology, combining analysis of Nigeria's full BIT portfolio, ICSID and ad hoc petroleum arbitration awards involving Nigeria, the PIA 2021's transitional provisions, and international investment law doctrines including legitimate expectations, fair and equitable treatment, and proportionality. Theoretical engagement draws on international investment law scholarship, regulatory takings theory, and policy space literature from global health and trade law contexts. The original calibration framework developed distinguishes between protected stabilisation interests and legitimate regulatory reform space, and proposes model BIT renegotiation language for Nigeria. This framework makes original theoretical contributions to international investment law and Nigerian petroleum law scholarship. Keywords: international investment law, right to regulate, Nigeria, BIT, petroleum sector.