International economic relations are often compared to a sports game. Within this game, states and private companies compete for influence, market shares, and resources. Competition is unfair when the field has a slope. In keeping with this sports analogy, the ‘game’ of international economic relations depends on a level playing field (LPF). International economic exchange is fair only when this playing field lacks a slope. This article argues that the LPF in international economic law does not require fully equalizing the regulatory burden across market actors, even when incorporating sustainability considerations. Instead, whether regulatory divergences lead to an uneven playing field depends on the nature, intensity, and source of such divergences, and varies on a case-by-case basis. This is important because countries have increasingly introduced LPF measures that seek to achieve comparable regulatory burdens. LPF measures cover a wide range of matters, including environmental and labour standards, subsidies, competition law, and state-owned enterprises.