As a general matter, federal courts are forbidden to modify a sentence after it has been imposed. However, there are a few narrow exceptions to that rule. One such exception is Rule 35(b) of the Federal Rules of Criminal Procedure. This rule allows for a sentence reduction if the defendant has provided substantial assistance to the government in the investigation or prosecution of another person. Under Rule 35(b), upon a government’s motion made within one year of sentencing, a federal court is allowed to reduce a sentence if, after sentencing, the defendant provided substantial assistance. If the government brings a substantial assistance motion more than a year after sentence had been imposed, the court may reduce the sentence if the assistance involved one of the following:
- The information provided to the government was not known to the defendant until more than one year after sentencing;
- The information was given within one year of sentencing, but the information that was provided did not become useful to the government until more than a year after sentencing; or