What is the problem of the multiplicity of actions in class actions?

Discussing the problem of the multiplicity of actions in class actions involves considering numerous topic of civil procedure including the availability of individual actions, the availability of joinder of parties, the availability of consolidation and trial together, the nature of representative actions, the right to opt-in to a representative action, the right to opt-out of a representative action, the subject-matter jurisdiction of a court (jurisdiction simpliciter), the matter of forum conveniens, and the theory of res judicata. Further, the problem of the multiple class actions also involves constitutional law and conflicts of law rules about; (1) the joinder of foreign plaintiffs and defendants; (2) choice and proof of foreign law; and (3) the enforcement of foreign judgments. Moreover, the problem involves a consideration of the policy goals of class actions and the economics of class actions. Further still, the topic also involves several hidden agenda items including court parochialism and insularity, lawyer avarice, and lawyer conflicts of interest. The problem of the multiplicity of proceedings, particularly in the context of class proceedings, is no small problem, and as will be seen from the discussion below, carriage motions are part of the solution, but the problem is larger than carriage motions. (See also McSherry v. Zimmer GMBH, supra.)