No ex post facto law, or law impairing the obligation of contracts of or making an irrevocable grant of special privileges or immunities, shall be passed. (Source: Illinois Constitution.)
EX POST FACTO LAWS AND IMPAIRING CONTRACTS
Ill. Const. art. 1, § 16 — under BILL OF RIGHTS.
Ill. Const. art. 1, § 16
EX POST FACTO LAWS AND IMPAIRING CONTRACTS