BANGOR, Maine — A federal judge has granted class action status to a lawsuit filed by Maine retirees over the elimination in 2011 of cost-of-living adjustments for Maine state employee retirement benefits.

The ruling, issued Wednesday by U.S. District Judge George Singal, clears the way for about 28,000 retired teachers, Maine State Police troopers and state employees to have their day in court.

The next step in the case will be for Singal to decide two legal issues in the case — whether the laws governing cost-of-living increases prior to a change in the law last year constituted a contract and, if so, whether the 2011 legislation constituted an “impairment” of that contract, according to court documents.

Lawyers are expected to file motions on the questions by the end of March. A date for oral arguments has not been set.

The lawsuit was filed in February in U.S. District Court in Bangor after the budget passed by the Legislature the previous year froze, then capped at 3 percent cost-of-living increases for state employees.

Originally, the 15,000-member Maine Association of Retirees sued the Maine Public Employees Retirement System. In October, U.S. District Court Judge Nancy Torresen, who on Nov. 19 recused herself from the case, allowed three state employee unions — Maine State Employees Association, Maine Education Association and Maine State Troopers Association — to join the case.

Torresen did not give a reason for her recusal but she worked from 1994 to 2001 for the Maine attorney general’s office, according to her biography posted on the Maine U.S. District Court website.