75 ILCS 10/9
The board of directors of any tax-supported public library, or the contracting authority of other types of libraries which are eligible for membership in a library system and according to the rules and regulations of the State Librarian and such regulations established by that library system, may, with the approval of the State Librarian, join the library system in which the contracting authority is located or where the facility desiring to participate is located. All member libraries shall assume and maintain the rights, privileges and duties of system membership established by the board of directors of the system. The right to suspend a library from membership for failure to fulfill its obligations under law or by agreement is vested in the system board with the concurrence of the State Librarian. However, the board of library directors or trustees of any public library, or the contracting authority of any other type of library that is a member of any library system, will retain all powers specified by law or in articles of incorporation, except as otherwise provided in this Section.
75 ILCS 10/9