Contracting Sustainability: International Investment Contracts as Governance Instruments for Sustainable Investment

While the ongoing debates on sustainability reform in international investment law (IIL) have largely centred on procedural amendment, treaty recalibration, and domestic regulation, the role of international investment contracts (IICs) in this agenda has remained comparatively underexplored. This thesis argues that IICs can function not as mere commercial arrangements, but more as governance instruments capable of accommodating normative demands of sustainability at the project level. Based on such premise, the core research question is how, and to what extent, IICs can and can better perform governance functions for sustainability good. This research is primarily descriptive and evaluative, while also normatively oriented. The main objective is to reconfigure IICs as governance instruments for sustainable investment, and to clarify their distinctive capacities, limits, and proper position within a multilevel legal framework regulating investment. Methodologically, this project adopts doctrinal analysis as the principal approach. Its doctrinal inquiry is guided by an analytical framework that conceptualises the normative demands of sustainable development in temporal, distributive, and integrative terms, and use these dimensions for diagnosis, evaluation, and analysis throughout the thesis. This framework is firstly applied to picture the research background, diagnosing why the prevailing IIL architecture is limitedly capable of accommodating the pressures from sustainable development, and why existing procedural, treaty-based, and domestic-law reforms remain inadequate. The framework also structures the substantive analysis of the sustainability clauses in contemporary IIC practice, as both a categorizing device and an evaluative benchmark. This analysis draws on an original dataset of around 200 publicly available post-2012 investor-State contracts, primarily in the natural resource sectors and supplemented by other public-project contracts. Within this dataset, the “sustainability clauses” are grouped according to the functions they perform in respond to the temporal, distributive, and integrative dimensions of sustainability. Further analysis examines how sustainability is contractualised, through which clauses, and what recurring or sector-sensitive patterns emerge, and evaluates how effective or limited these arrangements are in addressing the corresponding normative demands. Some normative implications will be drawn from this qualitative analysis for more effective sustainability-oriented contractual design. The final part pursues a systematic doctrinal analysis on the interaction between IICs and investment treaties, domestic laws, and other relevant international obligations. It examines their overlaps and conflicts for clarifying how IICs’ governance role of should be understood, bounded, and coordinated within the broader legal framework regulating international investment. This project contributes to the ongoing IIL sustainability reform in three ways. Firstly, it brings IIC into the reform discussions and redefines it as a distinct though bounded site of sustainability-oriented investment governance. Such reconfiguration shifts from an ex post adjudication-centred logic to a governance-centred logic of ex ante anticipation, adjustment, and coordination. Secondly, it reframes the way sustainability is analysed in IIL discourses. Rather than approaching sustainability through the logic of public-interest justification or through broad eco-social claims, this research analyzes this notion from its temporal, distributive, and integrative normative demands, which is more capable of evaluating IICs’ governance function. Thirdly, it repositions IICs within the broader legal framework to consider how IICs can better practice its governance role in pursing sustainable development. It goes beyond the abstract “public-private” ontological debates over the IIL itself, but relies on a more systematic and functionalist perspective on what can or cannot be done at the IIC level for practical good of the IIL reform.