5 ILCS 465/11
The United States national flag, when flown at half-staff, should be first hoisted to the peak for an instant and then lowered to the half-staff position. The flag should be again raised to the peak before it is lowered for the day. On Memorial Day, the flag should be displayed at half-staff until noon only, then raised to the top of the staff. By order of the Governor, the flag shall be flown at half-staff upon the death of a present or former official of the government, the death of a member of the Armed Forces who dies while serving on active duty, the death of a first responder who dies while serving in the line of duty, or any other death or occurrence that the Governor deems worthy of such a recognition. An order of the Governor to fly the flag at half-staff may be for any length of time up to the greatest length of time enumerated in Section 7 of the United States Flag Code. For the purposes of this Section, "half-staff" means the position of the flag when it is one-half the distance between the top and bottom of the staff.
5 ILCS 465/11