The CAFA Mass Action Numerosity Requirement: Three Problems with Counting to 100

56 Pages Posted: 23 Mar 2010

See all articles by Guyon Knight

Guyon Knight

Fordham University School of Law

Date Written: March 1, 2010


This Note examines the mass action provision of the Class Action Fairness Act of 2005 (CAFA) and the difficulties courts have encountered when applying its seemingly simple 100-person numerosity requirement. “Mass actions” are a broad category of nonclass aggregate litigation over which CAFA extended federal jurisdiction. This Note examines three interpretations of the numerosity requirement advanced in recent cases. These interpretations have advocated, in turn, not finding a mass action when a case has more than 100 formally joined plaintiffs, recognizing the existence of a single mass action broken up among parallel suits with fewer than 100 plaintiffs, and finding a mass action in cases with only a single, representational plaintiff. These arguments concerning the meaning of the mass action numerosity requirement stem from the confluence of three factors: Congress’s intent for courts to interpret CAFA broadly, the similarities between class actions and nonclass aggregate litigation, and ambiguities in the mass action statute. Although no perfect reading of the statute is possible, this Note suggests that courts strictly interpret the statute going forward, only counting formal parties to a single action in order to determine if CAFA’s numerosity threshold has been achieved.

Keywords: CAFA, mass action, mass actions, complex litigation, Class Action Fairness Act

Suggested Citation

Knight, Guyon, The CAFA Mass Action Numerosity Requirement: Three Problems with Counting to 100 (March 1, 2010). Fordham Law Review, Vol. 78, p. 1875, 2010, Available at SSRN:

Guyon Knight (Contact Author)

Fordham University School of Law ( email )

140 West 62nd Street
New York, NY 10023
United States

Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Abstract Views
PlumX Metrics