In the case of Percy Dillon v. United States (2009), the U.S Supreme Court ruled that federal judges have discretion to reduce sentences for crack cocaine offenses below new minimum levels established by the U.S Sentencing Commission. The decision was based on a 7-2 vote, with Justice Sonia Sotomayor writing for the majority. The case involved Percy Dillon who had been sentenced in 1993 to more than 26 years in prison for selling and possessing crack cocaine. In light of changes made by Congress and the Sentencing Commission which reduced penalties for such crimes, he sought a sentence reduction but was denied because his original sentence fell within both old and new guidelines ranges. However, this ruling clarified that while courts are required to consider guideline ranges when modifying a defendant's term, they can also take into account other statutory factors including nature of offense or characteristics of defendant thereby allowing them some leeway in reducing sentences.

In the dissenting opinion for Percy Dillon v. United States, Justice Stevens argued that the majority's interpretation of 18 U.S.C §3582(c)(2) was too narrow and failed to fully consider Congress' intent in passing the statute. He contended that Congress intended to give judges discretion when reducing sentences under this provision, not limit them as the majority suggested. The decision should be based on factors such as a defendant’s behavior while incarcerated or other relevant considerations rather than strictly adhering to now-rejected sentencing guidelines. By limiting judicial discretion in these cases, he believed it contradicted both legislative intent and previous court rulings which emphasized individualized sentencing decisions based on all available information about a defendant's conduct and potential for rehabilitation.