DETROIT (AP) -- A judge blocked a new Michigan law Wednesday that's aimed at ending union dues paid by home health care workers who are private contractors and not public employees.

The decision by U.S. District Judge Nancy Edmunds was a defeat for Republican lawmakers and GOP Gov. Rick Snyder, who have been trying to unwind unusual labor deals arranged during the administration of Gov. Jennifer Granholm, a pro-union Democrat who left office in 2011.

Edmunds said the April law as it applies to SEIU Healthcare Michigan is illegal because it interferes with a contract that doesn't expire until February.

"What's the hurry?" said the judge, who ruled from the bench and promised to issue a written order later.

SEIU Healthcare represents 42,000 home health care aides, although they are self-employed and not government workers. Some are family members of the sick, who need help with bathing, meals, medication and other tasks.

Union dues, totaling $400,000 to $500,000 per month, are deducted from taxpayer subsidies that go to home workers. In a court filing, the union said it would be "ruinous" to the organization if it lost the money.

The union in 2005 won the right to represent the home-based workers after the Department of Community Health, under the Granholm administration, struck a deal with a three-county agency that serves the elderly. That led to a creation of another group to coordinate services and come up with a registry of home-care providers.

More than 80 percent of the 8,000 ballots cast were in favor of a union. SEIU Healthcare said its members are making at least 33 percent more than before the union stepped in.

"It's not just about dues. It gives people a voice," union lawyer John Canzano said Wednesday.

Critics, especially conservatives, complain that the Granholm administration was simply helping her allies in organized labor at a time when union membership was slipping. A similar arrangement involving thousands of independent day-care workers who got state subsidies and paid union dues ended in 2011 without a change in law.