Group IV: Parties · Last amended March 1, 2019 · Last verified July 14, 2026
Editor’s Note: Subsections (a) through (c) were amended effective September 27, 1971. Subsections (d) and (e) were added effective September 27, 1971. Amendments Effective January 1, 2005. The amendments are technical. Neither the court nor the advisory committee considered the amendments to the federal rule, effective December 1, 2003, which revised subdivisions (c) and (e) and added new subdivisions (g) and (h).
Advisory Committee Note — 2019 Amendment: The amendments retain Rule 23 and add Rule 23(b) and (d)(2). Rule 23(b) permits aggregation of the value of class members’ claims to reach the district court threshold jurisdictional amount, and Rule 23(d)(2) permits substituting a class representative when a representative party is unable or unwilling to continue as the class representative.
Amended eff. 9-27-71; Amended eff. 1-1-05; Amended eff. 3-1-19.
A class action lets one or a few people stand in for a much larger group who share the same basic dispute, instead of everyone filing their own lawsuit. Rule 23 starts with four threshold requirements every proposed class must clear: the group has to be so large that joining everyone individually would be impractical, there must be legal or factual questions common to the whole group, the representatives' claims or defenses must be typical of the class, and the representatives must be capable of adequately protecting everyone else's interests. The rule also allows representatives to add up the value of every class member's individual claim when figuring out whether the case meets the court's jurisdictional threshold.
Clearing those four requirements is not enough by itself; the case also has to fit one of three additional patterns. Separate lawsuits might risk inconsistent rulings that leave the opposing party facing contradictory standards, or might practically decide the outcome for absent class members without them ever getting a say. Or the opposing party might have acted in a way that applies to the whole class, making injunctive or declaratory relief appropriate for everyone at once. Or common questions might outweigh individual ones enough that a class action is the best way to handle the dispute efficiently, a determination that weighs things like how much class members want to control their own cases and how hard the class would be to manage.
Once a case is allowed to proceed as a class action, the court has to decide that formally, as early as practical, and that decision can be revisited before the case is over. Depending on which type of class action is involved, class members may be entitled to individual notice, along with the right to opt out, and the eventual judgment has to describe exactly who is bound by it. Courts can also manage class litigation through orders addressing notice, procedure, and how claims are presented, and a class action cannot be dismissed or settled without the court signing off and notifying the class first.
Four things: the class has to be large enough that joining everyone individually would not be practical, there must be legal or factual questions common to the class, the representatives' situations must be typical of the class, and the representatives must be able to adequately protect the interests of everyone in the class.
It has to fit one of three additional situations: a risk of inconsistent rulings or rulings that would effectively decide the case for absent members, conduct by the opposing party that applies to the whole class and calls for injunctive or declaratory relief, or common questions predominating enough that a class action is the superior way to resolve the dispute.
It depends on which basis the class was certified under. When the case proceeds because common questions predominate and a class action is the superior method, the rule requires the best practicable notice, including individual notice where feasible, along with the right to be excluded from the class.
No. Rule 23 requires court approval before a class action can be dismissed or compromised, and it requires that class members be notified of the proposed dismissal or settlement.
The court must give class members an opportunity to substitute in a new class representative who meets the adequacy requirement, unless the original representative was the one being sued rather than the one suing.