Duhaime's Law Dictionary

Commonality Definition:

A feature of a group of people seeking to be certified for a class action, that there are questions of law and fact common to the prospective group (class).

Related Terms: Class Action, Community of Interest

Commonality is a requirement in some jurisdictions for certification of a proposed class action by a proposed group.

In the United States, for example, the procedural rule for certification includes, inter alia, this requirement: that "there are questions of law and fact common to the class".

Known as the commonality, Justice Pregerson of the United States Court of Appeal, in Dukes v Wal-Mart summarized the law of commonality as follows:

"Commonality focuses on the relationship of common facts and legal issues among class members. (The requirement for commonality) has been construed permissively. All questions of fact and law need not be common to satisfy the rule. The existence of shared legal issues with divergent factual predicates is sufficient, as is a common core of salient facts coupled with disparate legal remedies within the class.

"The commonality test is qualitative rather than quantitative — one significant issue common to the class may be sufficient to warrant certification.... [P]laintiffs may demonstrate commonality by showing that class members have shared legal issues by divergent facts or that they share a common core of facts but base their claims for relief on different legal theories."

In Re Wells Fargo, Justice Patel added these words:

"To fulfill the commonality prerequisite ... plaintiff must establish that there are questions of law or fact common to the class as a whole. (The) Rule ... does not mandate that each member of the class be identically situated, but only that there be substantial questions of law or fact common to all. Individual variation among plaintiffs' questions of law and fact does not defeat underlying legal commonality, because the existence of shared legal issues with divergent factual predicates is sufficient...."


  • Dukes v. Wal-Mart, Inc., 509 F. 3d 1168 (2007)
  • In re Wells Fargo Home Mortgage Overtime Pay Litigation, 527 F. Supp. 2d 1053 (2007)

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