Berry reviews the major theories for why legislative intent differs from regulatory output including: (1) theories of commission inadequacy, (2) group theories of political science, and (3) group theories of regulation offered by economists. He reviews the salient literature in each type and concludes that none alone incorporates a sufficient explanation for the wide range of regulatory outcomes. Such an explanation, he maintains, requires an analysis of all three actors, and of the variation in the incentives, resources, and goals of each.