Federal sentencing is governed under the United States Federal Sentencing Guidelines. Each year, the guidelines are updated and/or amended. Federal sentencing guidelines took effect in 1987. The guidelines apply only to crimes convicted in the federal court system. They are not mandatory. The description of each type of federal sentencing and the levels of offense seriousness appear in the document or guide along with an in depth sentencing table. Under federal sentencing guidelines, each specific crime has a base level. There are 43 different levels. These base levels increase or decrease in accordance with the consideration of different factors. These include the amount of loss involved, the conduct of the accused, the offender's role in the crime and the criminal history of the defendant.