INTRODUCTION

The basic idea of Art. 46 is to deal with closely related claims in one set of proceedings. Parallel or consecutive proceedings relating to different aspects of the same dispute are not only costly and inefficient but are also liable to lead to conflicting outcomes. The principles of economy and of finality militate in favour of hearing and deciding all aspects of a dispute in one set of proceedings. (Cf. Art. 26, paras. 124–131.)

An incidental claim arises as a consequence of the primary claim, such as interest or compensation for procedural costs. An additional claim is made by way of a later addendum to the original claim. A counterclaim is put forward by the respondent. The three types of claims may be referred to collectively as ancillary claims (see paras. 32–34 infra).

Provisions for a simultaneous decision on ancillary questions are not uncommon in instruments governing international adjudication. Examples may be found in the Rules of the International Court of Justice (Art. 80), in the 1958 International Law Commission's Model Rules on Arbitral Procedure (Art. 19 on counterclaims or setoff claims and Art. 20 on possible amendments to a claim or defence), in the 1998 International Chamber of Commerce Rules of Arbitration (Arts. 5(5), 19) and in the 1976 UNCITRAL Arbitration Rules (Art. 19(3)).