5 ILCS 120/2.01
All meetings required by this Act to be public shall be held at specified times and places which are convenient and open to the public. No meeting required by this Act to be public shall be held on a legal holiday unless the regular meeting day falls on that holiday.
Except as otherwise provided in this Act, a quorum of members of a public body must be physically present at the location of an open meeting. If, however, an open meeting of a public body (i) with statewide jurisdiction, (ii) that is an Illinois library system with jurisdiction over a specific geographic area of more than 4,500 square miles, (iii) that is a municipal transit district with jurisdiction over a specific geographic area of more than 4,500 square miles, or (iv) that is a local workforce investment area with jurisdiction over a specific geographic area of more than 4,500 square miles is held simultaneously at one of its offices and one or more other locations in a public building, which may include other of its offices, through an interactive video conference and the public body provides public notice and public access as required under this Act for all locations, then members physically present in those locations all count towards determining a quorum. "Public building", as used in this Section, means any building or portion thereof owned or leased by any public body. The requirement that a quorum be physically present at the location of an open meeting shall not apply, however, to State advisory boards or bodies that do not have authority to make binding recommendations or determinations or to take any other substantive action.
Except as otherwise provided in this Act, a quorum of members of a public body that is not (i) a public body with statewide jurisdiction, (ii) an Illinois library system with jurisdiction over a specific geographic area of more than 4,500 square miles, (iii) a municipal transit district with jurisdiction over a specific geographic area of more than 4,500 square miles, or (iv) a local workforce innovation area with jurisdiction over a specific geographic area of more than 4,500 square miles must be physically present at the location of a closed meeting. Other members who are not physically present at a closed meeting of such a public body may participate in the meeting by means of a video or audio conference. For the purposes of this Section, "local workforce innovation area" means any local workforce innovation area or areas designated by the Governor pursuant to the federal Workforce Innovation and Opportunity Act or its reauthorizing legislation.
5 ILCS 120/2.01