Sentencing has two prominent purposes: punishment and rehabilitation. After a jury or judge determines that the defendant is guilty, the punishment or sentencing phase of the criminal trial begins. There is no constitutional right to have a jury impose punishment. In federal court, only the judge determines the sentence under complex federal sentencing formulas. Many states follow the federal court's lead and do not allow a jury to determine punishment.
Each crime has a range of punishments that may be imposed after conviction. In some states, the defendant makes the choice whether to have a jury impose a sentence or leave it in the hands of the judge. This decision is generally strategic, since juries can become inflamed and impose the harshest sentence available. Likewise, some judges are tougher than others on convicted defendants and the defendant may choose to take his chances with a jury.
The convicted defendant must be present when his punishment is announced. In some states, the punishment must be announced orally by the judge to the defendant. Once the punishment is pronounced and the defendant leaves the courtroom, he begins serving his sentence, which cannot be changed