The tribunal in the arbitration Suez and Others v The Argentine Republic (ICSID Case No ARB/03/19) has exercised its discretion to permit five non-governmental organisations, who are not parties to the arbitration, to submit amicus curiae briefs. The discretion to permit amicus curiae briefs was exercised pursuant to a power which the tribunal found it had under the ICSID Convention, in 2005. The ICSID Arbitration Rules were subsequently revised in 2006 to include an express power to allow amicus briefs, but the revised rules do not apply in this arbitration.

The tribunal considered that the five petitioners were respected non-governmental organisations who had expertise in human rights, the environment and the provision of public services. Given the high stakes in this arbitration the tribunal considered that the final award may have some influence on how governments and foreign investor operators of the water industry interact when faced with difficulties. The case presented sufficient aspects of public interest to justify an amicus curiae brief.