WASHINGTON (AP) - The Supreme Court on Monday stepped into a dispute between the state of Idaho and labor unions over payroll deductions for political activities.

The state asked the justices to take the case, which involves an Idaho law that prohibits cities, counties and school districts from making payroll deductions for donations to political candidates or parties.

Five labor unions and the Idaho state AFL-CIO successfully challenged part of the law in lower federal courts.

A federal judge and the 9th U.S. Circuit Court of Appeals in San Francisco concluded that local units of government and school districts could choose to stop making the payroll deductions, but that the state could not force them to do so.

The dispute centered on the free-speech rights of labor unions stems from Idaho's Voluntary Contributions Act, passed by the state Legislature in 2003.