In a 5-4 ruling, the U.S Supreme Court held that a defendant may not be sentenced under guidelines put in place after the crime was committed. In Peugh v. United States, the petitioner was convicted in federal court on five counts of bank fraud committed between 1999 and 2000, but was sentenced based on the 2009 version of the U.S. Sentencing Guidelines, resulting in a sentence of nearly twice the length as that outlined in the Guidelines from 2000.
Peugh’s attorneys argued that the Ex Post Facto Clause – which prohibits among other things the passage of laws that impose a greater penalty than the punishment in effect at the time of the crime – should have shielded him from the longer sentence. The argument was rejected by lower courts, but in a majority opinion written by Justice Sotomayor, the Court held that it was a violation of the Clause to sentence the defendant based on the newer Guidelines when the new iteration provides for a higher sentencing range.
The Court debated whether the Guidelines, which are no longer binding, are subject to the Ex Post Factor Clause. The dissenting opinion held generally that since the Guidelines are not mandatory, the Clause is not relevant. Justice Sotomayor – who asked some of the most pointed questions during oral arguments and seemed to be the swing vote on the case – opined that the Guidelines exert enough influence on the sentencing judge to be covered by the Ex Post Facto Clause.