A class action is a type of lawsuit in which one or a few plaintiffs seek to represent hundreds or thousands of plaintiffs with the same or similar claims against the same defendants. Rules of procedure in state and federal courts permit class actions in limited circumstances for the purpose of resolving similar disputes more efficiently than if each plaintiff filed a separate lawsuit.

In Missouri, class action lawsuits are governed by Missouri Rules of Civil Procedure, specifically Rule 52.08, which is similar to Federal Rule of Civil Procedure 23. This rule allows one or more plaintiffs to represent a larger group, or class, in a lawsuit if the class is so numerous that individual lawsuits would be impractical, there are questions of law or fact common to the class, the claims or defenses of the representative parties are typical of the claims or defenses of the class, and the representative parties will fairly and adequately protect the interests of the class. Class actions in Missouri are used to increase the efficiency of the legal process by allowing cases with common issues to be decided together, thus conserving judicial resources and providing a uniform resolution to all class members. The court must certify a lawsuit as a class action for it to proceed as such, and this certification process is a critical stage in these cases. If certified, the class action can address a wide range of issues, including consumer fraud, corporate misconduct, and other situations where a large group of individuals has been affected by the same legal issue.