What is commonality?

Commonality is a Rule 23(a) certification requirement that there be at least one question of law or fact common to all class members, capable of generating a common answer that resolves an issue central to the case. The Supreme Court's decision in Wal-Mart Stores v. Dukes (2011) tightened this standard, holding that shared questions must be capable of class-wide resolution, not merely raise the same general topic.

Commonality failed in Dukes itself because the plaintiffs alleged discretionary, store-by-store pay and promotion decisions with no company-wide policy tying them together, meaning no single answer could resolve the claims of all class members at once. Cases built around a single standardized policy, form contract, or uniform product defect tend to satisfy commonality more easily than cases involving individualized decision-making by different managers or salespeople. This requirement overlaps heavily with predominance, though predominance sets a higher bar that applies specifically to damages classes.

Last reviewed 2026-08-22.