A class action, sometimes called a class action case, class action suit or group litigation, is a claim brought by one or more people on behalf of the interests of a large group.
Specifically, a class action lawsuit is one filed by a group of people sharing a common legal position against a defendant and which can be efficiently and fairly tried in a single action.
A class action lawsuit may be filed by shareholders, ex-employees, consumers, or any group of affected individuals. Among other things, class action claims may arise from shareholder activism, alleged securities law violations, and bankruptcy cases. In the US, Rule 23 of the Federal Rules of Civil Procedure sets out the prerequisites for having an action certified as a class action in a federal court.
The person who is named as the claimant or the defendant in a class action is called the representative.