The reform goal of promoting reasonable consistency and reducing disparity in sentencing is meaningless without a frame of reference--consistency or disparity relative to what underlying principles? In order to decide that two offenders are similarly situated and thus should receive similar sentences (or that they are dissimilar and should receive different sentences) we must first define the relevant sentencing factors (the offense and offender characteristics that judges should consider in determining appropriate sentences) and the weight to be given to each of these factors. The choice and weighting of sentencing factors depends, in turn, on the punishment purposes which the sentence is supposed to serve.

Sentences can serve many purposes, and these purposes are often in conflict. Some of the most difficult conflicts are between proportionality principles, on the one hand, and case-specific crime-control or restorative-justice purposes, on the other. Proportionality serves both retributive (just deserts) and practical (utilitarian) sentencing purposes. Under a retributive theory, sanctions should be scaled in proportion to each offender's blameworthiness, and equally culpable offenders should receive equally severe sanctions. Sentencing proportionality and uniformity also have practical benefits, such as reinforcing public views of relative crime seriousness and maintaining public respect for criminal laws and the criminal justice system...