ST. PAUL — A contentious fight over union organizing among certain home-based child care and home health care workers is headed back to court.

Opponents say they will challenge a law signed just days ago. It gives the American Federation of State Counties and Municipal Employees and the Service Employees International Union a window to press for a unionization vote. Advocates argue the unions could secure higher reimbursement rates and better industry standards.

The Democratic-controlled Legislature approved the organizing after an earlier attempt by Gov. Mark Dayton to allow it through executive order was overturned in court.

A group calling itself Childcare Freedom planned to file the lawsuit Wednesday. Foes have complained that a union would compel independent business owners to join and pay dues regardless of their stance.