"Our investigation has found merit in the verified complaints, which allows us to commence this litigation," says Ozanne in a statement. "This litigation does not address the merits or the wisdom of the legislation."

Senate Republicans had been stymied by 14 Democrats who fled the state last month to deprive the GOP-controlled Senate of the 20-member quorum needed to pass Gov. Scott Walker's budget repair bill, which included a measure to effectively end collective bargaining for public employees. A week ago, Republicans hastily called a joint conference committee, including members of both legislative houses, to consider a bill that was stripped of fiscal elements, allowing the legislation to be passed by a simple majority.

State law requires 24 hours notice for such meetings unless "good cause" exists. The Republicans' notice was short of two hours.