Federal district judges have a great deal of discretion. The presumption is the that the district judge, who in effect, is the trial judge for the majority of federal criminal cases, is in the best position to evaluate the defendant, the witnesses, the evidence and the credibility of all those who appear in his or her courtroom.
These judges were able to exercise that discretion when sentencing offenders. But then Congress created the United States Sentencing Commission (USSC) to develop uniform sentencing guidelines for serious federal crimes, and in 1987 the guidelines were made mandatory.
These guidelines went from mandatory to advisory with the U.S. Supreme Court's decision in United States v. Booker. Given that federal judges had long decried the tyranny of the Guidelines, there were some expectations that Booker would result in a revolution in sentencing, since judges no long had to follow the Guidelines, and could create sentences that departed from Guideline requirements.
That has not happened. Sentences today are virtually the same as they were prior to Booker. One federal judge suggests that this is due to the cognitive effect known as "anchoring."
Because the Guideline's sentence is always presented as the first piece of information in a presentencing report (PSR), he believe this "anchors" the judges eventual sentence. He supplies studies that show that judges are subject to anchoring bias and to "blind spot" bias, which makes it almost impossible for them to recognize the anchoring biases in their own sentences.
He suggest that the simplest way to minimize this anchoring effect is to move the Guideline's recommendation to the end of the PSR and have the judge create a tentative sentence using only the section 3553(a) factors first, and then consider the Guideline's recommendation in light of the unbiased tentative sentence.
Journal of Criminal Law and Criminology, "Confronting Cognitive "Anchoring Effect" and 'Blind Spot' Biases In Federal Sentencing: a Modest Solution For Reforming a Fundamental Flaw," Mark W. Bennett, Volume 104, Issue 3, Fall 2014