How does a lawsuit become a class action? Under Federal Rule of Civil Procedure 23, the plaintiff must first satisfy the four class-prerequisites — a class so numerous that joinder is impracticable, questions of law or fact common to the class, claims typical of the named plaintiff's claims, and a representative who will fairly protect the class — and then fit the case into one of Rule 23(b)'s three class types, the overwhelmingly dominant one being (b)(3): common questions predominate over individual ones and a class is superior to other methods of adjudication. Certification is decided by the judge on evidence, often with a full hearing and expert battle, and it is the case's fulcrum: certified, settlement value multiplies; denied, the claims scatter into individual suits or die.
Political Digest publishes information, not legal advice.
What does each prerequisite actually require?
Numerosity is mechanical — classes of 40-plus generally qualify. Commonality asks for at least one common question capable of class-wide resolution; the Supreme Court's reading in Wal-Mart v. Dukes (2011) requires the common contention to be capable of a common answer — in employment discrimination, a policy or practice, not a mosaic of individual decisions. Typicality screens representatives whose own facts diverge from the class. Adequacy tests both the representative's interests and class counsel's competence and independence.
Why predominance decides most modern cases
Predominance is where class actions live or die: if liability or damages turns on individualized inquiries — each consumer's reliance, each patient's medical history, each worker's specific circumstances — common questions do not predominate. The Supreme Court's Comcast v. Behrend (2013) tightened the match between the damages theory certified and the trial theory, and TransUnion v. Ramirez (2021) pushed a parallel Article III question: every class member must have a real, de facto injury, thinning classes of uninjured members that once padded certification.
What happens at the certification stage procedurally?
- Motion and briefing: plaintiffs move, defendants oppose — certification battles frequently outspend later merits litigation.
- Evidentiary hearing: the court may consider merits evidence to the extent it overlaps the Rule 23 questions (Eisen limits conditioning certification on merits, but the line blurs in practice).
- Interlocutory appeal: Rule 23(f) permits defendants an immediate appeal of certification grants — discretionary, but frequently exercised in high-stakes cases, adding a year of appellate gatekeeping.
- Notice and opt-out: certified (b)(3) classes trigger individual notice to members, who may exclude themselves.
Settlement classes and objectors
Most certified classes settle, and settlement certification flips the incentive: both sides now favor certification, so Rule 23(e) arms objectors — class members who challenge the deal — with rights to discovery on the negotiation and a court duty to test adequacy against a «second-sweep» of the class's interests. The objector bar is entrepreneurial, courts are skeptical of coupon settlements, and attorney-fee allocation triggers its own litigation (the «common fund» doctrines).
Arbitration's shadow
Because class certification is the leverage, companies increasingly contract around it: arbitration clauses with class-action waivers, enforceable for consumer and employment disputes since AT&T Mobility v. Concepcion (2011) and Epic Systems v. Lewis (2018), move these disputes into individual arbitration. The practical consequence for reading class-action news: check first whether the defendant's contracts contain arbitrations clauses — many headline-worthy claims never reach Rule 23 at all.
FAQ
What is a (b)(3) class?
The dominant class type — common questions predominate and class treatment is superior — with notice and opt-out rights for members.
Can a certification ruling be appealed immediately?
Yes, by permission under Rule 23(f), routinely sought in significant cases.
What killed the Wal-Mart class?
Absence of a common policy: a discretionary employment system could not yield a common answer to the discrimination question.
For more context, read How Congress Counts Electoral Votes Under the Reformed Rules.
For more context, read state attorneys general.
For more context, read qualified immunity.