Power - the use or threat of force - addresses the compliance problem by closing the gap that can arise between interest and the requirements of justice and the rule of law. At times it may be the only measure that can close this gap. Yet using power to address the compliance problem creates its own quite serious set of difficulties - difficulties that may be viewed as particularly acute problems of knowledge and interest. In this chapter, I shall explain how using power creates serious problems of knowledge. Innocent errors of judgment are possible, indeed inevitable, whenever fallible human beings are called upon to use force justly.

Apart from the problem of innocent errors, using force to address the compliance problem gives rise to serious problems of interest in which those authorized to use force to ensure justice use it instead to aggrandize themselves and their allies. In Chapters 12, 13, and 14, I discuss this problem and how it argues for a structure of law enforcement that constrains abuse. In this part, we shall see not only that these twin problems of power reinforce the need for the liberal conception of justice and the rule of law, but also that, we may do better to tolerate some compliance problems than to suffer the full brunt of the problems of power.