IN OTHER articles, we have examined the issues and problems arising from arbitrations which have been (or are purported to be) initiated by or against a limited number of individuals or companies which have in common being (or having been) involved in the same or related project(s) or transaction(s). In contrast, this article will be devoted to another aspect of complex arbitrations: that is, arbitrations initiated by groups of individuals (which may be thousands) or in other words, group actions.1 For obvious reasons, explained below, it will mainly focus on the US practice of class actions. Group actions may be injunctive or remedial, meaning that they can seek injunctive relief as well as money damages. They are still relatively rare and unknown in civil law countries. Most of the statutes authorizing multiparty actions in Europe concern consumer protection. For example, in a number of countries,2 independent administrative authorities or consumer organizations have for many years been recognized as having locus standi to apply to the courts for an injunction or a prohibition order in relation to forbidden or unfair commercial practices. On the other hand, the legislation of EU Member States has also been (or is about to be) amended to incorporate the provisions of Directive 98/27/EC which permits consumer organizations to apply to courts in fellow Member States for an injunction against an infringement of any of a number of consumer trading Directives, covering areas such as misleading advertising, unfair contract terms, consumer credit, package holidays, and consumer guarantees, that are committed in the organization’s own state by an entity in the fellow state. But these actions are representative proceedings, quite different from group actions. Although some EU and non-EU states also have legislation on group litigation,3 its scope and impact remains quite limited. The only …