205 ILCS 5/43
When a notice is required to be given to stockholders or directors under this Act, or by the charter or by-laws of any state bank, a waiver thereof in writing, signed by the person or persons entitled to said notice, whether before or after the time stated therein, shall be deemed equivalent thereto. Whenever the vote of the stockholders or the directors, as the case may be, at a meeting thereof is required or permitted to be taken in connection with any corporate action, by any section of this Act, the meeting and vote of stockholders or directors may be dispensed with, if all of the stockholders or all of the directors who would have been entitled to vote upon the action if such meeting were held, shall consent in writing to such corporate action being taken. In the event that the action which is consented to is such as would have required the filing of a certificate under any of the other sections of this Act, if such action had been voted upon by the stockholders or directors at a meeting thereof, the certificate filed under such other section shall state that written consent has been given hereunder, in lieu of stating that the stockholders or directors have voted upon the corporate action in question, if such last mentioned statement is required thereby.
205 ILCS 5/43