Amicus curiae is a method of non-party intervention in legal disputes in place in several national procedural rules. Currently present in common law jurisdictions, amicus curiae is an old practice whose functions have evolved over the years. It has its roots in Roman law, where at the time an amicus curiae was a learned, respected, independent appointee of the court whose role was to advise and assist the court in reaching a just decision. However, over the years in common law systems, it developed into a means of counter-balancing the adversarial nature of the proceedings. Now, amicus’ primary objective is to represent a trade association or a public advocacy group to influence the outcome of a decision.

The utility and convenience of this method has been heavily debated since 2000 in the investment arbitration context. While remaining lively, the debate eventually led to the inclusion of specific provisions regulating non-party interventions in the revised version of some arbitration rules (see for instance Article 37 (2) of the 2006 ICSID Arbitration Rules and Article 1128 and 1129 of the NAFTA). Doors have been explicitly opened to the intervention of amicus curiae in investor-state proceedings in response to the request for further transparency in proceedings where public interests are by definition involved.

The amicus curiae allowed under the ICSID arbitration rules can be seen as a compromise between the Roman original amicus curiae and the final common law development of it. The wording of Article 37(2) is revealing in this respect: “ determining whether to allow such a filing, the Tribunal shall consider, among other things, the extent to which: (a) the non-disputing party submission would assist the Tribunal in the determination of a factual or legal issue related to the proceeding by bringing a perspective, particular knowledge or insight that is different from that of the disputing parties; [...] (c) the non-disputing party has a significant interest in the proceeding”.

Jul-Sep 2015 issue

ICC International Court of Arbitration