Any system of justice purporting to be civilized must pursue two basic principles: (1) that people similarly circumstanced are to be treated equally under the law; (2) that people administering the law are not permitted to act arbitrarily or to prescribe individually the rules governing their actions and decisions. Both of these principles were persistently violated through well over half the twentieth century in the sentencing of people for crimes in the United States. The steady violations were produced by a combination of sentimental good intentions, puritanical severity and irrational misconceptions concerning the effects of punishment and the capacity of those commissioned to administer punishment. As the century wanes, the long course of error has been identified. This is a time of intensive sentencing reform. We are vexed now in a familiar way by doubts about the efficacy and the side effects of the reforms.