205 ILCS 610/4
Any day on which a bank, or any one or more of its offices, is closed during all or any part of its normal banking hours under Section 2 of this Act shall be, with respect to such bank or, if not all of its offices are closed, then with respect to any office or offices which are closed, a legal holiday for all purposes with respect to any banking business of any character. No liability, or loss of rights of any kind, on the part of any bank, or director, officer, or employee thereof, shall accrue or result by virtue of any closing authorized by this Act.
The provisions of this Act shall be construed and applied as being in addition to, and not in substitution for or limitation of, any other law of this State or of the United States, authorizing the closing of a bank or excusing the delay by a bank in the performance of its duties and obligations because of emergencies or conditions beyond the bank's control, or otherwise.
205 ILCS 610/4