A divided Wisconsin Supreme Court has reinstated Gov. Scott Walker’s union-busting law curbing collective bargaining. In a 4-to-3 ruling, the court overturned a lower court’s ruling that Republican legislators failed to provide sufficient public notice before passing the measure in March. The law sharply curbs nearly all collective bargaining rights of state employees. In its new decision, the court ruled the lower court judge, Dane County Circuit Judge Maryann Sumi, had overstepped her authority. Thousands of protesters returned to the State Capitol in Madison on Tuesday as the full legislature began debating Walker’s budget.