WTO members must incorporate TSDCs and new analytical frameworks into WTO rules to enable panels to apply sustainability tests. Constitutionalising the WTO appears to be a promising approach for integrating these necessary elements into its legal framework. However, while desirable, the constitutionalisation of the WTO faces significant challenges associated with global constitutional theories. Given this, several doubts arise regarding the constitutionalisation of the WTO. The first doubt concerns its utility and whether the WTO should possess constitutional features, particularly in terms of its structure. The second doubt pertains to the institutional structure of global governance and the relationship among international governmental organisations. Can there be a hierarchical or fragmented global constitutional system that allows international organisations to govern global affairs? For the WTO, this raises the question of whether the current global governance system permits it to address non-trade issues and, if so, how. The third doubt involves the harmony of WTO constitutional norms, specifically whether WTO rules can reconcile economic freedoms with human rights. The final doubt relates to the ideology of economic constitutionalism. Constitutionalism can be used to defend various liberal ideologies and protect different legal values. What legal values should the constitutionalisation of the WTO aim to protect? In this Chapter, I will discuss the role of constitutionalisation in integrating the UN SDGs into WTO law and address these critical issues associated with this global constitutional theory.