Today, the Supreme Court held in Alabama Department of Revenue v. CSX Transportation, Inc. that the Court of Appeals for the Eleventh Circuit properly concluded that CSX’s competitors are an appropriate comparison class for CSX’s claim under 49 U.S.C. §11501(b)(4), but erred in refusing to consider whether Alabama could justify its decision to exempt motor carriers from its sales and use taxes through its decision to subject motor carriers to a fuel-excise tax.  The Court instructed the Eleventh Circuit to consider whether Alabama’s fuel-excise tax is the rough equivalent of Alabama’s sales tax as applied to diesel fuel, and therefore justifies the motor carrier sales-tax exemption. Justice Scalia delivered the opinion of the Court, in which Justices Roberts, Kennedy, Alito, Sotomayor, and Kagan joined.  Justice Thomas filed a dissenting opinion, in which Justice Ginsberg joined.