Article 9. Class Actions · Last amended 1975 · Last verified July 21, 2026
In one sentenceCPLR 901 lists the five prerequisites a case must meet to proceed as a class action, numerosity, common questions that predominate, typical claims or defenses, adequate representation, and superiority over other methods, and bars class treatment of statutory penalties absent specific authorization.
Full Text of CPLR 901
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a. One or more members of a class may sue or be sued as representative parties on behalf of all if: 1. the class is so numerous that joinder of all members, whether otherwise required or permitted, is impracticable; 2. there are questions of law or fact common to the class which predominate over any questions affecting only individual members; 3. the claims or defenses of the representative parties are typical of the claims or defenses of the class; 4. the representative parties will fairly and adequately protect the interests of the class; and 5. a class action is superior to other available methods for the fair and efficient adjudication of the controversy.
b. Unless a statute creating or imposing a penalty, or a minimum measure of recovery specifically authorizes the recovery thereof in a class action, an action to recover a penalty, or minimum measure of recovery created or imposed by statute may not be maintained as a class action.
Plain-English Summary
Article 9 is New York's answer to the question of when one plaintiff, or a handful of them, can stand in for a group too large to litigate claim by claim. CPLR 901(a) sets out five things a case must show before it can proceed as a class action, and a court has to find every one of them satisfied, not just some.
The class has to be so numerous that joining every member individually would be impracticable. The legal or factual questions common to the class have to predominate over questions that would need to be answered member by member. The claims or defenses of whoever proposes to represent the class have to be typical of the class as a whole, not an outlier. Those representative parties, and by extension their counsel, have to be capable of adequately protecting the interests of everyone in the class, including members who never show up in court. And a class action has to be the superior way to resolve the controversy compared with individual suits or other available procedures.
Subdivision (b) closes off one particular use of the class-action device. Unless a statute creating a penalty, or a statutory minimum measure of recovery, specifically says that penalty or minimum can be recovered in a class action, a plaintiff can't use Article 9 to aggregate individual statutory penalties into one class-wide award. The concern is proportion: a modest per-violation penalty can turn into a liability wildly out of scale with the underlying conduct once multiplied across a class, and the legislature reserved that outcome for the statutes that expressly authorize it.
Frequently Asked Questions
What are the requirements for a class action in New York?
CPLR 901(a) requires numerosity, common questions that predominate over individual ones, typical claims or defenses among the representatives, adequate representation, and a finding that a class action is the superior method for resolving the dispute.
How many people need to be affected to bring a class action in New York?
There's no fixed number. CPLR 901(a)(1) asks whether the class is so numerous that joining every member individually would be impracticable, which courts assess case by case.
What does typicality mean in a New York class action?
It means the representative plaintiff's claims or defenses arise from the same conduct or course of events as the rest of the class, so a ruling on the representative's case meaningfully resolves the class's case too.
Can a class action be used to recover a statutory penalty in New York?
Only if the statute creating the penalty, or setting a minimum recovery, specifically authorizes recovering it through a class action; CPLR 901(b) otherwise bars class treatment of statutory penalties.
How does CPLR 901 compare to Federal Rule of Civil Procedure 23?
The two share a similar structure, numerosity, commonality, typicality, and adequacy all appear in the federal rule too, and CPLR 901(a)(5)'s superiority requirement tracks the federal rule's predominance-and-superiority test for damages classes, though New York courts apply CPLR 901 as state law, independent of federal case law construing Rule 23.
What does it mean for common questions to predominate over individual ones?
It means the legal or factual issues shared across the class outweigh, in significance, whatever individual issues would still need resolving for each member, which is what makes one class-wide proceeding more useful than many separate suits.
Who decides whether a proposed class action satisfies these five requirements?
The court decides, typically on a certification motion under CPLR 902, and the case may proceed as a class action only after the court finds all five CPLR 901 prerequisites met.
Amendment History
Add, L 1975, ch 207, § 1, eff Sept 1, 1975.
Source & verification. Provision text, History, and Advisory
Committee Notes are reproduced verbatim from the Consolidated Laws of New York.
Last verified July 21, 2026.
· Official source
Also known as:New York class action requirementsCPLR class certification standardnumerosity commonality typicality adequacy superiority New Yorkclass action prerequisites New Yorkcan I file a class action in New YorkNew York class action lawsuit requirementsNew York equivalent of federal Rule 23