Which is NOT one of the four prerequisites for filing a class action?

• A. Commonality
• B. Adequacy
• C. Numerosity
• D. Predominance

Answer: (D)

In class-action practice, four requirements under Rule 23(a) must be met to bring a class action: numerosity (so many people that joinder is impracticable), commonality (shared questions of law or fact), typicality (the representative’s claims are typical of the class), and adequacy (the representative can fairly protect the class’s interests). Predominance is not one of these filing prerequisites; it’s a separate standard used when deciding whether a class should be certified under Rule 23(b)(3). Predominance asks whether common questions truly predominate over individual issues, and it governs certification—not the ability to initiate the action. So the item that is not a four-prong filing prerequisite is Predominance.