As experiments with class actions spread to more distant shores, especially in countries of civil law backgrounds, a recurring question arises: what is the relation of the private class action to the customary regulatory power of the state? The response offered here is that, in fact, the class action stands in three different postures to state authority: as a direct challenge, as a complement, and as a rival. Recent class action cases in the U.S. are analyzed to examine these three functions and to give a distinct justification for each. At bottom, each justification turns on a contested commitment to a diversity of regulatory authority-—here termed “regulatory pluralism”-—that lends coherence to all three forms of interaction between the state and private authority, claiming the mantle of the “private attorney general.”

First Page