The creation of the Appellate Body (AB) of the WTO entails an unprecedented delegation of power to an international adjudicator, since the WTO requires states to ensure compliance of their domestic regulations with the sweeping obligations in WTO agreements. This is legitimized in some academic analysis and much political rhetoric in terms of the rule of law, suggesting that the role of the adjudicator is merely to apply the precise words of the texts agreed by states, according to their natural meaning. The AB has supported this, by adopting a formalist approach which combines an objectivist view of meaning with a legalistic style of judgement. However, both the general structure and many of the specific provisions of the WTO agreements are indeterminate and raise issues of interpretation which were known to be highly contestable. Although the delegation of adjudication in its early phase was considered to be of a narrow technical function, in the current phase interpretation is more clearly seen to involve a flexible application of principles to cases in the light of the policies involved. The role would be better legitimized by adopting a more open epistemology and reasoning which could be accessible to a wider constituency. However, it is constrained by fear of usurping the political legitimacy of the governments to which it is primarily accountable, and they in turn are motivated by a reluctance to admit to their domestic constituencies how much power has been transferred to supranational instances such as the AB.