735 ILCS 5/11-303
Such action, when prosecuted by a citizen and taxpayer of the State, shall be commenced by petition for leave to file an action to restrain and enjoin the defendant or defendants from disbursing the public funds of the State. Such petition shall have attached thereto a copy of the complaint, leave to file which is petitioned for. Upon the filing of such petition, it shall be presented to the court, and the court shall enter an order stating the date of the presentation of the petition and fixing a day, which shall not be less than 5 nor more than 10 days thereafter, when such petition for leave to file the action will be heard. The court shall also order the petitioner to give notice in writing to each defendant named therein and to the Attorney General, specifying in such notice the fact of the presentation of such petition and the date and time when the same will be heard. Such notice shall be served upon the defendants and upon the Attorney General, as the case may be, at least 5 days before the hearing of such petition.
Upon such hearing, if the court is satisfied that there is reasonable ground for the filing of such action, the court may grant the petition and order the complaint to be filed and process to issue. The court may, in its discretion, grant leave to file the complaint as to certain items, parts or portions of any appropriation Act sought to be enjoined and mentioned in such complaint, and may deny leave as to the rest.
735 ILCS 5/11-303