What is Class Action?

Legal Definition
A class action, class suit, or representative action is a type of lawsuit where one of the parties is a group of people who are represented collectively by a member of that group. The class action originated in the United States and is still predominantly a U.S. phenomenon, but several European countries with civil law have made changes in recent years to allow consumer organizations to bring claims on behalf of consumers.
-- Wikipedia
Legal Definition
A class action is a procedural device that permits one or more plaintiffs to file and prosecute a lawsuit on behalf of a larger group, or "class". Put simply, the device allows courts to manage lawsuits that would otherwise be unmanageable if each class member (individuals who have suffered the same wrong at the hands of the defendant) were required to be joined in the lawsuit as a named plaintiff. See Hansberry v. Lee, 311 U.S. 32, 41, 61 S.Ct. 115, 118 (1940).

Historically, various types of so-called “representative actions” have existed “since the earliest days of English law.” Federal Rules of Civil Procedure, finally bringing into life the class action device pursuant to the original version of Rule 23. However, it was not until 1966, but a scant 40 years ago, that the class action mechanism “gained its current shape in an innovative 1966 revision.” Rule 23 requires that the district court make the following findings: (1) the number of class members renders it impracticable to join them in the action, (2) the class members' claims share common questions of law or fact, (3) the claims or defenses of the proposed class representatives are typical of those for the rest of the class, and (4) the proposed class representatives will adequately protect the interests of the entire class. FRCP, Rule 23(a).

Furthermore, in addition to the numerosity, commonality, typicality and adequacy of representation requirements of Rule 23(a), the district court must make at least one of the following findings: (1) requiring separate actions by or against the class members would create the risk of inconsistent rulings, or that a ruling with respect to individual class members may be dispositive of other class member claims thereby “substantially impair[ing] or imped[ing] their ability to protect their interests”; (2) the party against whom the class seeks relief “has acted or refused to act on grounds generally applicable to the class” so that injunctive or declaratory relief as to the entire class would be appropriate; or (3) common questions of law or fact common “predominate” over class member specific questions, and that proceeding by way of class action would be “superior to other available methods” for resolving the dispute. FRCP, Rule 23(b).
Legal Definition
Legal action involving a large group or class of people. Without having every member of the class join the action, a few individuals initiate a court case becoming representatives of the group .