Unions sue to stop Chicago pension overhaul

Current and retired city workers and their labor unions have filed a lawsuit arguing a law overhauling Chicago's pension systems is unconstitutional.

The lawsuit filed Tuesday in Cook County circuit court also asks a judge to stop the law from taking effect Jan. 1.

Chicago has the worst-funded pension system of any major U.S. city.

Legislation approved last year seeks to eliminate a $9.4 billion unfunded liability in two pension systems by increasing contributions and cutting benefits. It would affect about 57,000 laborers and municipal employees.

The plaintiffs are 12 current and former workers and four unions, including AFSCME Council 31 and the Illinois Nurses Association.

Mayor Rahm Emanuel says the law is constitutional. He says the changes are needed to ensure pension funds remain solvent and retirees receive benefits.