2-801.Prerequisites for the maintenance of a class action.

Section 2-801 is Illinois's own class-action statute, separate from the federal class-action rule, even though its four requirements will look familiar to anyone who knows Rule 23. Before a court lets a case go forward as a class action, it must find that joining every affected person as an individual party would be impracticable because there are too many of them — the numerosity requirement.

The court must also find that common questions of law or fact tie the class together, and that those common questions outweigh whatever questions apply only to individual class members. A class where each member's claim turns on its own distinct facts is a poor fit for this device, no matter how many people share a grievance.

Third, the people bringing the case on the class's behalf must be capable of protecting the interests of everyone else in the class — adequacy of representation. A representative with interests that conflict with the class, or without the resources or incentive to litigate the whole class's claims, does not satisfy this element.

Finally, the court must find that a class action is an appropriate method for the fair and efficient adjudication of the controversy. This last requirement lets a court weigh whether the class device serves the case better than individual suits, even after the first three boxes are checked, and it is the court — not the parties — that decides whether all four findings can be made.