Federal Sentencing publications
This report by the Government Accountability Office suggests that despite the increased sentencing authority afforded to tribes by the Tribal Law and Order Act, none are exercising this authority. Only about a third of tribes have plans on exercising this increased sovereignty.
The United States Sentencing Guidelines form a basis for all sentences in federal court. In certain circumstances, federal judges can give a sentence lower than the suggested guideline range. For the most part, however, only those sentences within the guideline range are considered reasonable. To calculate a sentence, first look up the federal crime committed and see what the base sentence for that crime is. Then, look to see whether any "enhancements" apply.