How many people do you need for a class action?

The first requirement in Rule 23(a) is known as numerosity. Rule 23(a)(1) allows a class action only if "the class is so numerous that joinder of all members is impracticable." Joinder means naming every person as a plaintiff in one lawsuit. The test is not whether joinder is impossible, but whether it would be impractical given the number of people and the circumstances.

The Supreme Court has refused to set a number. In General Telephone Co. of the Northwest v. EEOC (1980), the Court said the numerosity requirement "requires examination of the specific facts of each case and imposes no absolute limitations." In that same opinion, the Court observed that a group as small as 15 employees would be too small to meet the requirement, judged by cases where certification had been denied.

Numerosity is only the first of four Rule 23(a) requirements. See what class certification is for the others.

Although no statute sets a minimum, courts have developed rules of thumb:

The Second Circuit held in Consolidated Rail Corp. v. Town of Hyde Park (1995) that numerosity is presumed at a level of 40 members, a line that many federal courts across the country cite. These are guides, not rules: a court may certify a smaller class if members are spread across the country, cannot easily be identified, have small claims they would never bring alone, or fear retaliation (common in employment cases). It may reject a larger class if everyone is easy to find and join.

A different number matters for which court hears the case. The Class Action Fairness Act of 2005 gives federal courts jurisdiction over large interstate class actions. Under 28 U.S.C. 1332(d), a federal court has jurisdiction over a class action when the aggregated claims exceed $5 million and any class member is a citizen of a different state than any defendant, but the law does not apply if the proposed classes total fewer than 100 members.

So a class of 60 people can still be a valid class action, but it would generally need to be in state court, or in federal court on some other basis such as a federal statute. CAFA also treats "mass actions," where 100 or more people's monetary claims are proposed to be tried jointly, as removable to federal court. See class action vs. mass tort.

A common misconception is that you must gather a group before a lawyer will file. You do not. Rule 23(a) says "one or more members of a class may sue" as representative parties on behalf of all members. Many class actions are filed by a single named plaintiff, with others added later from different states or subgroups.

What the lawyer needs is evidence that many others were affected the same way, such as company-wide policies, customer counts from public filings, a breach notice listing how many people were affected, or a stream of similar complaints. The rest of the class is identified later through company records. Our guide on how to start a class action lawsuit walks through the steps.

A class action with a million people in the class can still fail. The class also needs common questions whose answers resolve everyone's claims at once, a representative whose claims are typical, and adequate counsel. For damages cases, common issues must predominate.

Class size can also shrink during a case. In TransUnion LLC v. Ramirez, decided June 25, 2021, the Supreme Court held that only 1,853 of the 8,185 class members, those whose misleading credit reports were actually sent to third parties, had the concrete harm needed to recover damages. Under Rule 23(c)(5), a court can also divide a class into subclasses, each of which is treated as its own class. Class definitions can also be narrowed to certain states, dates, or products, as with the class definitions in the Costa Del Mar repair settlement, which excludes Florida residents.

Workplace overtime claims under the Fair Labor Standards Act use a different system. Under 29 U.S.C. 216(b), no employee becomes a party to an FLSA collective action unless they give written consent and it is filed with the court. Because workers must opt in, there is no Rule 23 numerosity test for the collective itself, though courts still decide whether the workers are "similarly situated." Some FLSA collective actions involve only a few dozen workers. See unpaid overtime lawsuits.

If you think a company treated you and others unfairly, the number of people you personally know about does not need to be large. A free case review takes about two minutes and connects you with independent attorneys who handle these cases, and you can browse lawsuits attorneys are investigating or pursuing to see if a case already exists.