The ruling came in the case of Marvin Peugh, who helped run two farm-related businesses in Illinois. After experiencing cash flow problems, he was convicted on five counts of bank fraud for conduct occurring in 1999 and 2000.
He was sentenced to 70 months in prison under the 2009 Sentencing Guidelines range, but his lawyers argued he should have been sentenced under the more lenient 1998 guidelines in effect at the time of his violations -- 30 to 37 months.
They cited the ex post facto clause of the U.S. Constitution -- defendants can't be punished by retroactive laws.
The federal courts ruled that since the guidelines were just that -- guidelines, not laws -- his sentence was constitutional.
But the Supreme Court, in the majority opinion written by Justice Sonia Sotomayor, said the ex post facto
clause "is violated when a defendant is sentenced under guidelines promulgated after he committed his criminal acts and the new version provides a higher sentencing range than the version in place at the time of the offense."
The opinion reversed the lower courts and sent the case back down for a new hearing in line with the Supreme Court opinion.