70 ILCS 1710/12
A majority of the Commissioners duly appointed at each time quorum is at issue shall constitute a quorum for the transaction of business of the Commission and the concurrence of a majority of the Commissioners present at any meeting where business is conducted is necessary for the Commission to take any action authorized by this Act, except that the executive committee, selected as hereinbefore provided, shall exercise such powers and authority of the Commission as are delegated to such committee by the bylaws and regulations adopted by the Commission or as is authorized the executive committee by Section 9 of this Act. Any Commissioner shall have authority and it shall be valid for him or her to vote by written proxy at any meeting of the Executive Committee or other committees of the Commission on which such Commissioner may serve, provided that proxies shall never be valid at any meeting of the full Commission and, provided further that no Commissioner shall be privileged to vote by written proxy at more than 2 successive meetings of the Executive Committee or other committees of the Commission on which such Commissioner may serve.
70 ILCS 1710/12