In 1986, Congress adopted a 100:1 ratio for prosecuting crack cocaine and powder cocaine offenses. If I was caught dealing 10 grams crack to James, I would receive the same penalty that I would if I was caught dealing him a kilo of powder cocaine. The US Sentencing Committee has long tried to persuade Congress to change this policy but Congress has always rejected the idea. The Supreme Court has also been reluctant to rule on the issue until now.
The Supreme Court accepted review in the straightforward case Kimbrough v. US. The district judge handed down a sentence that was below the standard sentencing guidelines because he felt the guidelines were excessively long. The circuit court rejected the district judge’s ruling and remanded the case for resentencing.
This case seems like a textbook political issue. The Court is more likely to rule on the constitutionality of a judge issuing a below-guidelines sentence than the constitutionality of the crack/powder ratio. I think a lot of the reason the court took on this case has to do with the Claiborne case that they had to end prematurely. Both of the cases have similar underlying issues and this could simply be a substitute.