The Indiana Supreme Court has unanimously upheld the state's right-to-work law, which bars employers from requiring workers to join unions or pay union dues as a condition of employment, in a victory for business groups.
Thursday's 5-0 decision reversed a lower court ruling that had found the law violated Indiana's constitution.
Prior to the law's adoption in 2012, there had been protests by hundreds of union supporters outside the statehouse in the capital of Indianapolis.
Indiana Attorney General Greg Zoeller had defended the law, while plaintiffs including Local 150 of the International Union of Operating Engineers (IUOE), which represents about 4,000 workers in northwest Indiana, had opposed it.
"We are deeply disappointed," said James Sweeney, IUOE Local 150's president and business manager, in a statement. "Because this decision is based on what we firmly believe to be a misinterpretation of federal law, we will consider petitioning the United States Supreme Court to hear this case."
In a statement, Zoeller said the decision "confirmed that the people's elected representatives in the legislature were within their legal authority to craft an economic policy prohibiting involuntary union dues."
On Sept. 2, a three-judge panel of the federal appeals court in Chicago also let the law stand, saying it did not violate the U.S. Constitution or federal labor law.
That court said that 24 U.S. states had some form of a right-to-work law, most with language resembling Indiana's.
In the state case, a state court judge in Lake County had concluded that the Indiana Right to Work Law violated a state constitutional ban against forcing anyone to provide "particular services," such as union representation for non-members, without being paid. A violation would be deemed a misdemeanor.
Writing for the Indiana Supreme Court, however, Justice Brent Dickson said the right-to-work law "merely prohibits employers from requiring union membership or the payment of monies as a condition of employment."
He concluded: "Any compulsion to provide services does not constitute a demand made by the State of Indiana."
The case is Sweeney et al v. Zoeller et al, Indiana Supreme Court, No. 45S00-1309-PL-596.
(Reporting by Jonathan Stempel in New York; Editing by Kevin Drawbaugh and Richard Chang)