The concept of the “level playing field” (LPF) has become a recurring metaphor in international trade negotiations, invoked by major trading powers, including the EU, the US, the UK, Japan, Brazil, and Switzerland, to characterise fairness in international economic relations. Yet, despite its widespread use, the concept remains normatively undertheorised and conceptually vague. This dissertation seeks to remedy this gap. It first maps and taxonomises the full range of LPF measures, instruments, and agreements introduced over the past decade, distilling a descriptive definition of LPF as the equalisation of competitive conditions through the internalisation of social costs and the integration of non-economic objectives (NEOs), such as environmental, labour, and human rights standards, into trade and investment policy. Building on this taxonomy, the dissertation situates LPF within theories of trade fairness, the economics of comparative advantage, and the principles of general international law. It argues that LPF operates as an “interstitial norm”: a norm that weaves together existing principles, including due diligence, permanent sovereignty, the polluter-pays principle, pacta sunt servanda, and non-discrimination, to provide coherent guidance where primary norms leave gaps. Finally, the dissertation operationalises this framework by developing a decision tree that distinguishes fair from unfair advantages, and applies it to concrete unilateral measures and treaty provisions. In doing so, it proposes a principled and coherent framework for the integration of NEOs into a competitive but fair global economy.
