Moving from the era of the New Deal into the 1980's and beyond, the book examines how developments in moral philosophy and political science, changes in administrative law, the 'green movement' of the 1980's and 1970's, and current struggles between proregulatory and deregulatory forces have affected perceptions of both power and duty among administrators and judges. Focus is on three basic dynamics established in the past: a shift from demanding that administrative decisions summate group preferences to demanding that these decisions be right; conflict over what is right (i.e., technically or rationally correct versus an ethically informed prudential best guess); and uncertainty over whether the decision should be arrived at by some less adversarial and formal deliberative process than has been the practice. The jurisprudential movement of the 1960's and 1970's demanded that regulatory agencies engage in synoptic adjudicatory processes. The movement denied that agencies exercised discretion, and, therefore also denied that the courts reviewing them did. There now is a movement toward prudential deliberation for the agencies, and the only way courts can check on agency discretion is by themselves engaging in prudential deliberation, that is, exercising discretion. Chapter notes and index.