Understanding Class Action Litigation In The US

What defines a class action lawsuit under U.S. law?

A class action lawsuit is a procedural device that allows one or more representative parties to litigate on behalf of a larger group (a "class") whose members share common legal or factual issues. Under U.S. federal law, the defining authority is Rule 23 of the Federal Rules of Civil Procedure (FRCP), which sets the requirements for certification and management. A class action differs from joinder or consolidation because unnamed class members are represented collectively without needing to file individually; the result binds all class members unless they opt out. Class actions are commonly used in contexts involving small individual damages, systemic harms, or widespread consumer or employment injuries, such as antitrust conspiracies, securities fraud, product liability, and wage-and-hour violations.