Inherent Powers of the WTO Appellate Body and ICSID tribunals – a tale of cautious convergence

The discharge of the ‘international judicial function’ is among the many forces that cause international judicial bodies to converge. Key to the exercise of the international judicial function is the principle of inherent powers. Inherent powers are conferred upon judicial bodies to safeguard the judicial function. Yet, for the WTO Appellate Body (AB) and ICSID tribunals (collectively, the tribunals), it is often assumed that while ICSID tribunals have broad inherent powers, the AB’s inherent powers are restricted. Does this mean that these tribunals are fragmented in the exercise of their judicial function, and consequently their
inherent powers, and if so, what factors contribute to such fragmentation? This chapter answers the above questions by examining the manner in which the AB and ICSID tribunals perceive their authority to exercise inherent powers through the examples of (a) objections to admissibility of a case; and (b) amicus curiae submissions. Using these examples, this chapter challenges absolutist assumptions about the inherent powers of the AB and ICSID tribunals.
Instead, it develops a nuanced understanding of the scope of the inherent powers of these tribunals through a study of their respective judicial functions. First, the meaning of ‘international judicial function’ is explored. Secondly, convergences in the judicial functions of the AB and ICSID tribunals are analysed. Thirdly, the factors that contribute to the adoption of divergent judicial policies by these tribunals are identified. Finally, the particular approaches of these tribunals towards their inherent powers is rationalized by highlighting the unique interplay between, and balancing of, the international judicial function and the structural and institutional limitations of these tribunals. In doing so, the chapter highlights the converging nature of the judicial function of these tribunals and dispels the notion that these tribunals are responsible for fragmenting the law on inherent powers. Alongside, by drawing on the divergences in the judicial framework of the tribunals, this chapter cautions against promoting convergence at the cost of carefully structured differences in the functioning of these tribunals.