Booker/Fanfan is an abbreviated reference to two separate cases that were heard together at the U.S. Supreme Court. In United States v. Booker, 543 U.S. 220 (2005), the U.S. Supreme Court decided important issues of federal sentencing guidelines in criminal cases. One portion of the opinion declared the federal sentencing guidelines to be advisory, rather than mandatory. This is referred to as the "remedy" portion of the opinion. By itself, the decision in Booker did not change the mandatory minimum laws.
The Court also declared that facts that increase sentences such as drug amount, loss amount, role, obstruction, or upward departures must be either admitted by the defendant or proven to a jury beyond a reasonable doubt. The reasoning is based upon the Sixth Amendment right to a jury trial. This part of the Booker opinion is referred to as the “merits” portion or the “constitutional violation” portion. Of the five justices who supported making the guidelines advisory, two are no longer on the court, Sandra Day O'Connor and William H. Rehnquist, then the chief justice.
