An employer, including a home rule unit, that employs a full-time law enforcement, correctional or correctional probation officer, or firefighter may not provide benefits to persons covered under this Act in a manner inconsistent with the requirements of this Act. This Act is a limitation under subsection (i) of Section 6 of Article VII of the Illinois Constitution on the concurrent exercise of powers and functions exercised by the State.
820 ILCS 320/20