The Indiana Supreme Court plans to hear a challenge to the state's Right to Work law on September 4.
A county judge previously ruled the law unconstitutional.
Indiana's Right to Work law bans union contracts that requires non-union employees to pay fees for representation.
State Attorney General Greg Zoeller last year appealed Lake County Judge John Sedia's ruling that the law violates a provision of the Indiana Constitution that says no person's services shall be demanded without just compensation.
Because unions are required by federal law to represent all employees in a workplace, not just members, Sedia said Right to Work forces unions to represent those non-members for free.
Both Republican and Democratic lawmakers, as well as legal experts, have said they expect the Supreme Court to uphold the law and reverse Sedia's decision.