Class Actions

Class actions allow one or more representative parties to litigate on behalf of a larger group that shares common claims. Federal class actions are governed by Rule 23 of the Federal Rules of Civil Procedure.

Rule 23(a) establishes four prerequisites that every class action must satisfy: (1) numerosity — the class is so numerous that joinder of all members is impracticable; (2) commonality — there are questions of law or fact common to the class; (3) typicality — the claims of the representative parties are typical of the class; and (4) adequacy — the representatives will fairly and adequately protect the interests of the class.

Wal-Mart v. Dukes heightened the commonality requirement, holding that plaintiffs must demonstrate that the class members' claims depend on a common contention capable of classwide resolution — meaning that determination of its truth or falsity will resolve an issue central to the validity of each claim in one stroke.

Beyond the prerequisites, the class must fit one of three categories under Rule 23(b). Rule 23(b)(1) applies when individual adjudications would create incompatible obligations for the defendant or impair other class members' interests. Rule 23(b)(2) applies when the defendant has acted on grounds generally applicable to the class, making injunctive or declaratory relief appropriate. Rule 23(b)(3) — the most common — applies when common questions predominate over individual questions and a class action is superior to other methods of adjudication.

Amchem Products v. Windsor held that settlement-only class actions must independently satisfy Rule 23's requirements, particularly predominance and adequacy of representation.