MADISON, Wis. (AP) -- A Dane County prosecutor has asked the state Supreme Court to reopen his lawsuit challenging Gov. Scott Walker's contentious collective bargaining law.

District Attorney Ismael Ozanne filed the suit in March alleging Republican lawmakers violated open meetings laws during the run-up to passing the measure. The case ended up in the Supreme Court. The court's four-justice conservative majority ultimately upheld the law in June.

But word broke earlier this month that one of the conservative justices, Michael Gableman, accepted free legal services from the law firm that defended the union measure.

Ozanne argued in filings Friday Gableman's participation in the union decision voided it. He asked the Supreme Court to vacate the ruling and disqualify Gableman from further proceedings if he doesn't remove himself.