Thousands of Philadelphia landlords will be eligible to join a federal lawsuit in which a judge found the city's method of placing liens on rental properties is unconstitutional.

U.S. District Judge J. Curtis Joyner this week certified a lawsuit filed by five landlords against Philadelphia Gas Works as a class action. That would open the action to potentially thousands of property owners who got socked for their tenants' unpaid gas debts.

The plaintiffs have asked Joyner to nullify all outstanding gas liens linked to deadbeat tenants, a move PGW said could cost it millions of dollars.

Joyner, in a memorandum dated Wednesday and distributed among parties on Friday, said he would rule on the requested relief at a later date.

"From our point of view, this is really good news," said David Wolf, whose commercial real estate company, Richmond Waterfront Industrial Park LLC, is one of the five landlords who filed the suit in 2014.

PGW spokesman Barry O'Sullivan said it would be premature to comment until the judge issues his final order.

Joyner in March issued a summary judgment in the landlords' favor, saying PGW's method of placing liens on landlords for tenant bills without adequate notice violated due process and constituted an unlawful taking of property. In some cases, landlords did not discover the liens on their properties until after the tenants were long gone and they could do nothing to recover the money.

Joyner also criticized PGW for referring aggrieved landlords to the Public Utility Commission, which typically dismissed their complaints because it has no jurisdiction over PGW's practice of filing liens.

Unlike investor-owned utilities, PGW as a government agency has the authority to place liens on property for unpaid bills. The lawsuit did not challenge the legality of liens, but focused instead on PGW's failure to give landlords adequate notice that their tenants had run up debts that could blow back on the landlords.

The case is Augustin et al v. City of Philadelphia in U.S. District Court. It was filed by landlords Lea and Gerard Augustin, Thomas and Donna McSorley, and Richmond Waterfront Industrial Park.

Their lawyers, the firm of Langer, Grogan & Diver, will serve as counsel for the class. The city is represented by the Archer & Greiner firm.