The Legal Reasoning of ICSID Tribunals - An Empirical Analysis

This empirical analysis of the use of interpretive arguments by ad hoc tribunals of the International Centre for the Settlement of Investment Disputes covers almost 100 cases decided during the past 10 years. The cases are analysed with a view to determining which arguments the tribunals use and how the arguments are used in light of Articles 31 and 32 of the Vienna Convention on the Law of Treaties. The analysis provides a basis for addressing the extent to which ICSID tribunals contribute to creating a predictable legal framework in which the interests of investors, states, and third parties are taken properly into account; the extent to which ICSID tribunals contribute to a coherent development of international investment law; and whether ICSID tribunals contribute to a 'fragmentation' of international law. Despite ICSID tribunals being ad hoc tribunals that solve legal disputes on the basis of heterogeneous legal sources, the article indicates that there is a tendency among ICSID tribunals to contribute to a homogeneous development of the methodology of international law. Nevertheless, the article concludes that ICSID tribunals could do significantly more to align their approaches to interpretive arguments with those of other international tribunals.