Who has final say in the duration of the offender's prison stay in a determinate sentence?

A "Judge" has final say in the duration of the offender's prison stay in a determinate sentence.

A judge is a man who directs court procedures, either alone or as a part of a board of judges. The forces, capacities, strategy for arrangement, discipline, and preparing of judges change generally crosswise over various jurisdictions. The judge should lead the trial in an unbiased way and, commonly, in an open court.

can you explain it better

answer; regard the action of other people negatively;