A spat between Cleveland and one of its labor unions over when firefighters should start work each day has escalated to a case before the Ohio Supreme Court over who should referee the fight. The high court this week ordered Cuyahoga County Common Pleas Judge Nancy Margaret Russo to file a brief by Friday that explains why she should be allowed to have a part in the case. The root of the court fight is a decision by fire Chief Angelo Calvillo to change the start time for firefighters working 24-hour shifts from 8:30 a.m. to 7 a.m. The case arises at a time when tensions between the union and the chief are smoking hot. City Council President Kevin Kelley has said he intends to hold a hearing to listen to the union’s concerns. Meanwhile, the city’s three-year collective bargaining agreement with the firefighters will expire March 31.