Can invocation of human rights enhance justice and social legitimacy in investment adjudication?

How should investment arbitrators and judges respond to the criticism that the legal privileging of foreign investors in international investment law (IIL) and arbitration risks undermining the human rights of citizens? Justice, the customary law rules on treaty interpretation, and the universal recognition of human rights require construing IIL in conformity with the human rights obligations of states rather than only in terms of economic utility and autonomy (e.g. of investors, arbitrators and states). Prioritizing foreign investments risks undermining ‘constitutional justice’ and human rights law (HRL), as emphasized by the European Court of Justice (section I). In investor-state arbitration, complainants, respondents, third parties (e.g. amici curiae) and arbitrators increasingly invoke human rights as procedural ‘due process rights’, part of the applicable law or relevant context for ‘systemic interpretation’ (II).Yet, just as the adoption of the proposed UN Agreement on Business and Human Rights remains contested, so remain judicial references to human rights – as applicable law or ‘systemic interpretation’ - in the settlement of investment disputes controversial. This contribution argues that judicial references to HRL can increase the source- and processbased ‘normative legitimacy’ and result-oriented, internal and external ‘social legitimacy’ of economic adjudication. Yet, judicial ‘administration of justice’ is no substitute for legislative reforms of IIL, which are necessary for protecting ‘constitutional and human rights integrity’, ‘deliberative’ and ‘constitutional democracy’ and public reason in multilevel governance of public goods (like sustainable development). HRL requires legislative and judicial reforms aimed at limiting neo-liberal interest group politics and authoritarian state-capitalism in IIL and adjudication (III)