As a key battleground in this year’s presidential election, Ohio has already seen its share of voting-related litigation. The U.S. Court of Appeals for the Sixth Circuit has already weighed in with several rulings on the counting of provisional ballots and on expanded early voting hours.

But there is another important legal issue peculiar to Ohio that hasn’t gotten much attention so far, though it will be a significant factor should the state’s election tally spark litigation. Under a little-noticed provision of Ohio law, federal election results cannot be challenged in state court.

The provision is relatively new. Before 2006, legal challenges to the results of any statewide or federal race went to the state Supreme Court first under a statutory procedure. But early that year, Ohio legislators passed a law prohibiting federal election results from being contested under state law. Such challenges must now be brought under federal law.

What’s not clear is how that would work. “There is no federal statutory law that creates the same sort of election contest as under Ohio law,” says professor Steven Huefner of The Ohio State University’s Moritz College of Law. A plaintiff might, for example, bring an equal protection claim in federal court, Huefner says, though there does not appear to be a precedent for pursuing such a claim.

Huefner notes that both of the big federal election litigation battles the country has seen in recent years—Bush v. Gore in Florida in 2000, and the fight that dragged on after the 2008 election for a U.S. Senate seat in Minnesota between Norm Coleman and Al Franken, who ultimately prevailed—began in state court.

Ohio’s state court exclusion was adopted amid a sweeping overhaul of voting laws passed by Republican lawmakers in the wake of the fierce battle between President George W. Bush and John Kerry for the state’s 20 electoral votes in 2004. Citing a host of alleged problems with Ohio’s election procedures, Kerry supporters contested the vote tally in a case that the state Supreme Court summarily rejected. (As a result of the 2010 census, Ohio now has 18 electoral votes.)