Rule 23
Rule 23 is the federal court rule that says when a lawsuit can be a class action and how a class settlement gets approved.
Also called: FRCP 23, Federal Rule of Civil Procedure 23, Fed. R. Civ. P. 23, Rule 23(b)(3)
Rule 23 is the federal court rule that says when a lawsuit can be a class action and how a class settlement gets approved.
What it means
Rule 23 of the Federal Rules of Civil Procedure is the rule that governs class actions in U.S. federal courts. It says when a case can be brought on behalf of a whole group, how the group is told about it, and how a settlement gets approved. State courts have their own class action rules, and many are similar to Rule 23.
Rule 23(a) lists four requirements. The class must be too large for everyone to join the case (numerosity). Its claims must share common questions (commonality). The representative's claims must be typical. And the representatives and their lawyers must protect the class (adequacy).
Rule 23(b) sets the types of class actions. The one behind most settlements that pay out is (b)(3), the money-damages class. Classes that mainly seek a court order, such as making a company stop a practice, fall under (b)(2). Later sections cover notice (c), settlement approval (e), appeals (f), class counsel (g) and attorney's fees (h). The rule was last amended in 2018.
What it means for you
Rule 23 shows up in the fine print of nearly every class settlement notice. When the notice says the judge found the deal "fair, reasonable, and adequate," that is the Rule 23(e) standard. For money-damages classes, the notice must be in plain language. It has to cover the class definition, your right to opt out and how, and the fact that a judgment binds you if you stay in. Rule 23(e)(5) also lets any class member object to a settlement. Knowing these points helps you read a notice and spot what is missing or looks wrong.
Example
Say a notice states that the court has "certified a Rule 23(b)(3) settlement class." That tells you three things. The case is a class action in federal court. Class members get notice and can opt out. And the class is seeking money, not just a court order. The notice should then explain who is in the class and how to claim.
FAQ
It is the type of class action most often used when the class seeks money damages. The judge must find that questions common to the class predominate over individual ones and that a class action is the superior way to resolve the dispute. Class members get notice and can opt out.
No. Rule 23 governs federal courts, and state courts follow their own class action rules. Many are similar but not identical, so details such as notice and opt-out rights can differ.
Related terms
- Fed. R. Civ. P. 23, Class Actions (Cornell Legal Information Institute)
- Federal Rules of Civil Procedure, as of Dec. 1, 2025 (U.S. Courts)
Updated Oct 18, 2026. Plain-English definitions for general information — not legal or tax advice.