65 ILCS 20/21-10
The city council shall have the power to fix the amount and penalty of the bonds of all city officers and of all municipal employees charged with the custody of money or property. It shall also have the power to require the giving of additional bonds, and to increase or decrease the amount and penalty of the bonds of any officer, and to require the giving of a new bond where the security of an original bond has become either insufficient or in any way impaired, upon penalty of removal from office. The power vested in the city council by this Section shall be so administered as to protect the interests of the city from danger of financial loss, and shall never be used as a means of removing any person from the civil service of the city without a hearing before the Civil Service Commission, in accordance with law. In any such case the city employee or official whose office is sought to be declared vacant by reason of a failure to give a new, additional, or increased bond, shall have the right to have a hearing before the Civil Service Commission upon the question so involved.
65 ILCS 20/21-10