40 ILCS 5/22-307
Whenever any city or village enacts an ordinance pursuant to this Division, no common law right to recover damages against such city or village for injury or death sustained by any policeman or fireman while engaged in the line of his duty as such policeman or fireman, other than the payment of the allowances of money and of the medical care and hospital treatment provided in such ordinance, shall be available to any policeman or fireman who is covered by the provisions of such ordinance, or to anyone wholly or partially dependent upon such policeman or fireman, or to the legal representative of the estate of such policeman or fireman, or to anyone who would otherwise be entitled to recover damages for such injury or death. Nothing in this Division 3 relieves any municipality with a population under 500,000 of its duties under the Workers' Compensation Act or the Workers' Occupational Diseases Act. Nothing in this Division 3 prevents any policeman or fireman in a municipality with a population under 500,000 from recovery under the Workers' Compensation Act or the Workers' Occupational Diseases Act.
If any action against such city or village to enforce a common law right to recover damages for negligently causing the injury or death of any policeman or fireman is pending, for trial or on appeal, at the time this Division shall come in force or is so pending at the time such ordinance is enacted, the amount of any award or allowance of money made pursuant to such ordinance shall not be paid while such action is so pending and shall be reduced, before payment, by the amount of any judgment obtained against such city or village in such pending action; or such allowance of money, if already paid, together with all moneys expended pursuant to such ordinance for medical care and hospital expenses, may be set off against such judgment, either in such pending action or through other appropriate action by such city or village.
40 ILCS 5/22-307