In 1984, the United States established the U.S. Sentencing Commission to develop sentencing guidelines for judges to apply in federal cases. The Federal Sentencing Guidelines incorporate the goals of sentencing (just punishment, deterrence, incapacitation, and rehabilitation); seek to provide certainty and fairness in issuing sentences, while permitting sufficient judicial flexibility to account for mitigating and aggravating factors; and reflect developments in the understanding of human behavior. Typically, the Guidelines provide a specific range of penalties (e.g., a fine between $X and $Y) for each offense. Part Q of the Guidelines addresses offenses involving the environment, conservation, and wildlife.
Although initially considered to be mandatory, the United States Sentencing Guidelines recently have been interpreted by the Supreme Court as being discretionary; however, trial courts are required to take them into account during sentencing.
For more information, see http://www.ussc.gov (which includes the Guidelines and related information).