The most important decision faced by the Commission was whether it should reflect existing sentencing practice in its guidelines or develop a policy for sentencing on its own initiative. The Commission chose the latter course. The Commission treated its policy choices as systemwide choices. The choice of rationale was treated as a choice of which of the various sentencing aims should be given priority in the guidelines system as a whole and of how much weight the various major sentencing factors (seriousness of the offense, extent of prior record, etc.) should carry in that system. Use of a sentencing grid in modeling the various policy alternatives facilitated this systemwide approach. The Commission adopted a prison population constraint, so as not to cause the current rated capacity of the State prisons to be exceeded. The guidelines were arrayed on a two-dimensional grid, with the vertical axis representing the seriousness of the current offense and the horizontal axis representing the prior criminal record. Great emphasis was given to the gravity of the current offense than to the criminal history. Beyond the basic structure of the guideline system, the Commission faced choices on how to rate offenders' crimes and criminal records and on the use of aggravation and mitigation. Issues resolved were the breadth of offense classifications, the number of offense-seriousness grades, assigning seriousness ratings to crimes, the omission of 'enhancements,' scoring the criminal records, exclusion of status factors, and the definition of aggravating and mitigating factors. A number of important decisions also had to be made regarding the imposition of limits on judicial discretion, including standards for departure from the guidelines and the reach of the guidelines. A total of 183 footnotes are provided.