55 ILCS 5/2-6010
The said board of commissioners shall have no power or authority to delegate to any committee or other person or persons the "power to act", when such "power to act" shall involve the letting of any contract or the expenditure of public money exceeding the sum of $2,500; and any action of said board, or of any committee thereof, or of any other person or persons in violation of this Section shall be null and void. No money shall be appropriated or ordered paid by said county commissioners beyond the sum of $2,500, unless such appropriation shall have been authorized by a vote of at least two-thirds of the members elected to the said county board. And no officer of Cook County, or other person, shall incur any indebtedness on behalf of the county, unless first authorized by said board of commissioners.
55 ILCS 5/2-6010