INDIANAPOLIS — A federal appeals court upheld Indiana's right-to-work law banning mandatory union fees on Tuesday in a split decision that was delivered a few days before the state Supreme Court hears separate challenges over whether the 2012 measure violates the state constitution.

Two 7th Circuit Court of Appeal judges, Daniel Manion and John Tinder, said the state law doesn't wrongfully take property from unions and is constitutional. They also said federal law does not pre-empt Indiana's right-to-work law, as union lawyers have argued.

Chief Judge Diane Wood dissented, writing that federal labor law "does not support such sweeping force for Indiana's right-to-work law," and arguing that her fellow judges on the three-judge panel did not completely understand the universe of national labor law.

The appeals court ruling could color arguments scheduled for Thursday before the Indiana Supreme Court, where a pair of cases from Lake County will challenge the law on state constitutional grounds. Judges in those two cases have said the law violates a provision of the Indiana constitution barring anyone from being forced to provide a service for free — in this case, union representation.

Indiana became the first Rust Belt state to approve a right-to-work law in 2012. The legislative fight drew thousands of union protesters to the Statehouse in 2011 and 2012, and it was one of Indiana's most divisive and drawn-out debates.

The law bars unions from mandating that non-members pay fees to the union for representation. Supporters of the law, pushed mostly by business groups, argue that mandatory fees amount to forced unionizing. But Democrats and labor unions said the law creates a "freeloader" dynamic, because workers can gain the benefits of the union without having to pay for membership.

Not long after Indiana enacted the law, Republicans in Michigan rushed through their own measure, making the state the 24th to approve right-to-work.

Attorney General Greg Zoeller, who is defending the state in both federal and state challenges to the law, hailed the ruling Tuesday.

"Now that the federal courts have concluded the statute the people's elected representatives in the Legislature passed does not violate federal law, we will argue that the statute also complies with the Indiana Constitution and ought to be upheld," Zoeller said in a statement.