In the case of Keith Lavon Burgess v. United States, 2007, the Supreme Court ruled that a prior state felony conviction for drug distribution constitutes a "serious drug offense" under federal law even if it would be classified as a misdemeanor under federal standards. The defendant, Mr. Burgess was convicted in South Carolina on two counts of distributing cocaine and later federally indicted for being a felon in possession of firearms and ammunition. He argued that his previous convictions should not qualify as serious drug offenses because they were punishable by less than ten years imprisonment under federal law - thus making him ineligible for enhanced sentencing guidelines which require such qualifications to apply. However, the court unanimously disagreed with this interpretation stating that Congress intended to include all state felonies regardless of their classification at the federal level when drafting these laws.

In the dissenting opinion for Keith Lavon Burgess v. United States, Justice Souter argued that the majority's interpretation of "felony drug offense" was too broad and inconsistent with Congressional intent. He contended that Congress intended to apply enhanced penalties only to serious drug offenses, not all state law felonies involving drugs as interpreted by the majority. The term “felony” in federal law generally refers to crimes punishable by more than one year of imprisonment; however, South Carolina’s classification of simple possession as a felony is an outlier compared with other states’ laws and should not be used as a basis for applying harsher federal sentences. Therefore, he disagreed with categorizing Burgess' prior conviction under South Carolina law for simple cocaine possession as a "serious drug offense," triggering mandatory minimum sentence enhancements under 21 U.S.C §841(b)(1). In his view, this misinterpretation could lead to disproportionate sentencing outcomes based on variations in state laws rather than on offenders' conduct or criminal history severity.