5 ILCS 220/5

Any one or more public agencies may contract with any one or more other public agencies to perform any governmental service, activity or undertaking or to combine, transfer, or exercise any powers, functions, privileges, or authority which any of the public agencies entering into the contract is authorized by law to perform, provided that such contract shall be approved by the governing bodies of each party to the contract and except where specifically and expressly prohibited by law. Such contract shall set forth fully the purposes, powers, rights, objectives and responsibilities of the contracting parties.