A class action lawsuit is a lawsuit brought by one or more people who are similarly situated to all other people who may have been injured by the same defendant in the same way.
Class Action lawsuits must meet requirements of numerosity (There are enough potential class members that simply adding each of them as a named party to the lawsuit would be impractical.), commonality (There are common questions of law and fact among all of the plaintiffs.), typicality (The claims or defenses of the named plaintiffs are typical of those of everyone else in the class.), and adequacy (The named plaintiffs fairly and adequately represent the interests of the absent class members.).
A class action lawsuit is often the only cost-effective means to remedy an injustice committed by powerful, multi-million dollar corporations and institutions. Some examples of successful class actions are in the area of discrimination in the workplace, environmental disasters, defective products, false advertising and deceptive practices, and securities fraud.