A court hearing Friday stemmed from a proposal to build a waste-to-energy plant in Allentown.
A group called Allentown Residents for Clean Air is suing the Lehigh County Elections Board.
The group wants voters to decide if a clean air ordinance is necessary to monitor the planned Delta-Thermo Energy plant, but the board denied the group's request for a referendum, so the group is asking a judge to overturn that ruling.
The judge heard arguments Friday from the board, the group and attorneys for Delta-Thermo.
The judge said she will issue her decision Monday.