In Ohio, on an arcane question of election law.
To wit, whether Congress, through the Help America Vote Act of 2002, has authorized the federal courts to enforce the desires of a private party, in this case being the Republicans.
Short version: Republicans lose their bid to direct Ohio's conduct of State election procedure.
Thus spake SCOTUS (and not just Justice Stevens; the entire Court) in reversing Tuesday's en banc decision of the Sixth Circuit Court of Appeals. Howard Bashman has the links.