Illinois Gov. Pat Quinn signed the pension bill on Monday.
A coalition of unions says it plans to file a lawsuit challenging the newly-signed law aimed at overhauling two of Chicago's pension systems.
We Are one Chicago is a group of unions that has also challenged the state's pension overhaul. In a statement Monday, the group says the plan addressing laborer and municipal employee pensions is unfair and unconstitutional.
The new law would affect about 57,000 laborers and municipal employees and retirees and seeks to eliminate the $9.4 billion shortfall by cutting benefits and increasing contributions.
The coalition claims the new law would slash the value of pensions and disproportionate affect minorities, women and low-income workers and retirees.