In the typical class action brought pursuant to Rule 23 of the Federal Rules of Civil Procedure, a single plaintiff brings claims on behalf of a group of absent plaintiffs. This structure provides the necessary mechanism to litigate claims where a defendant is alleged to have harmed a large group of individuals in a small enough amount that no single plaintiff has sufficient incentive on its own to pursue the wrongdoing individually.

But Rule 23 of the Federal Rules of Civil Procedure not only permits a representative plaintiff to sue on behalf of a class of persons or entities harmed by defendants, but also provides that a defendant may be sued as a member of a class: “one or more members of a class may … be sued as representative parties.” Fed. R. Civ. P. 23(a).