Ill. Admin. Code tit. 92, § 3000.1060 – Subpoenas

a) The Secretary, or any individual whom he has designated to preside over a hearing convened in accordance with this Part, may sign and issue subpoenas either on his own initiative or, upon the request of any person participating in that proceeding where that person makes an adequate showing that the information sought will materially advance the proceeding.
b) A subpoena may require the attendance of a witness or the production of relevant documentary or other tangible evidence in the possession or under the control of the person served, or both.
c) Service of a subpoena upon the person named therein shall be made by delivering a copy of the subpoena to such person. Delivery of a copy of a subpoena to a natural person may be made by handing it to the person, leaving it at his or her office with the person in charge thereof, leaving it at his dwelling place or usual place of abode with some person of suitable age and discretion then residing therein, or by mailing it by registered or certified mail to the person at the person's last known address. When the person to be served is not a natural person, delivery of a copy of the subpoena may be effected by handing it to a registered agent for service, or to any officer, director, or agent in charge of any office of the person, or by mailing it by registered or certified mail to that representative at his last known address.
d) The original subpoena bearing a certificate of service shall be filed with the Department official having responsibility for the proceeding in connection with which the subpoena was issued.
e) Any person to whom a subpoena is directed may, prior to the time specified therein for compliance, but in no event more than 10 days after the date of service of such subpoena, apply to the presiding officer who issued the subpoena, or if he is unavailable, to the Secretary, to quash or modify the subpoena. The application shall contain a brief statement of the reasons relied upon in support of the action sought therein. The Secretary, or the presiding officer, as the case may be, may:
1. 1) Deny the application;
2. 2) Quash or modify the subpoena; or
3. 3) Condition denial of the application to quash or modify the subpoena upon the satisfaction of certain just and reasonable requirements. The denial may be summary.
f) If there is a refusal to obey a subpoena served upon any person under the provisions of this section, the Department may request the Attorney General to seek the aid of the Circuit Court or any court of competent jurisdiction in which the person is found, to compel that person, after notice, to appear and give testimony, or to appear and produce the subpoenaed documents before the Department, or both.
(Recodified from 92 Ill. Adm. Code 107 (Department of Transportation) pursuant to P.A. 104-0025, at 49 Ill. Reg. 12509)