PORTLAND — A judge on Tuesday allowed three state employee unions to join the Maine Association of Retirees in its lawsuit against the Maine Public Employees Retirement System over the elimination last year of cost-of-living adjustments for Maine state employee retirement benefits.

The Maine State Employees Association, Maine Education Association and Maine State Troopers Association were granted permission by U.S. District Judge Nancy Torresen to intervene in the lawsuit, according to a media release.

The 15,000-member Maine Association of Retirees filed the original lawsuit in February.

The unions claim the elimination of cost-of-living adjustments for retired employees violated the Constitution as an unlawful taking of property without just compensation, and a violation of the contract clause.

“We are very pleased with Judge Torresen’s decision to allow my clients to intervene,” Jeffrey Neil Young, an attorney at McTeague Higbee in Topsham, said in a statement. “The unions represent a large number of individuals affected and are in the unique position to provide important information about the suit due to their longstanding representation of state employees, their expertise in these cases and their historical involvement with state employee retirement benefits.”

The court will issue a scheduling order shortly for this case to be heard.