What is the test for maintaining a class action?

In the U.S., civil rights class actions are brought under Rule 23(b)(2), which was created specifically for the purpose of dealing with civil rights actions where a defendant is charged with discriminating unlawfully against a class. A class action under Rule 23(b)(2) may be maintained if the general criteria for a class action is satisfied and if the party opposing the class has acted or refused to act on grounds that apply generally to the class, so that final injunctive relief or corresponding declaratory relief is appropriate respecting the class as a whole. Thus, the relief is limited to injunctive or declaratory relief. Monetary relief, unless it is incidental to injunctive or declaratory relief, is not permitted. See Walmart Stores v. Dukes, 564 U.S. 338 (2011).