In Wal-Mart, Inc. v Dukes (2011), the United States Supreme Court sharply limited the scope of class-action litigation by denying certification to a class of approximately 1.5 million current and former female employee alleging systemic sex discrimination. The Court’s decision turned fundamentally on the legal principle of “commonality,” as defined under Rule 23(a)(2) of the Federal Rules of Civil Procedure, which requires plaintiffs to demonstrate that their claims depend upon a common contention capable of classwide resolution.

Writing for the majority, Justice Scalia articulated a demanding standard: it is not enough for class members to allege that they suffered similar harms; they must also show that those harms stem from the same underlying policy or practice whose legality can be adjudicated uniformly across the class. In this case, the plaintiff contended that Wal-Mart’s decentralized system of managerial discretion, coupled with a corporate culture allegedly permissive of gender bias, resulted in widespread discrimination. However, the Court found that the discretion granted to local managers severed the necessary thread of commonality. Without a centralized, uniformly applied discriminatory policy, the plaintiffs’ grievances were too individualized to satisfy the requirements for class certification.

The Court’s reasoning reflects a broader skepticism toward expansive class-action mechanisms, particularly in employment discrimination cases where subjective decision-making predominates. By insisting on a tightly defined, common question of law or fact, the decision in Wal-Mart v. Dukes raised significant procedural barriers for plaintiffs seeking to aggregate claims of institutional discrimination. It underscored the judiciary’s role in policing the boundaries of collective litigation and reaffirmed the principle that procedural cohesion is a prerequisite to accessing the powerful mechanisms of the class-action device.