35 ILCS 120/2b
The Department may, after notice and a hearing as provided herein, revoke the certificate of registration of any person who violates any of the provisions of this Act. Before revocation of a certificate of registration the Department shall, within 90 days after non-compliance and at least 7 days prior to the date of the hearing, give the person so accused notice in writing of the charge against him or her, and on the date designated shall conduct a hearing upon this matter. The lapse of such 90 day period shall not preclude the Department from conducting revocation proceedings at a later date if necessary. Any hearing held under this Section shall be conducted by the Director of Revenue or by any officer or employee of the Department designated, in writing, by the Director of Revenue.
Upon the hearing of any such proceeding, the Director of Revenue, or any officer or employee of the Department designated, in writing, by the Director of Revenue, may administer oaths and the Department may procure by its subpoena the attendance of witnesses and, by its subpoena duces tecum, the production of relevant books and papers. Any circuit court, upon application either of the accused or of the Department, may, by order duly entered, require the attendance of witnesses and the production of relevant books and papers, before the Department in any hearing relating to the revocation of certificates of registration. Upon refusal or neglect to obey the order of the court, the court may compel obedience thereof by proceedings for contempt.
The Department may, by application to any circuit court, obtain an injunction restraining any person who engages in the business of selling tangible personal property at retail in this State without a certificate of registration (either because the certificate of registration has been revoked or because of a failure to obtain a certificate of registration in the first instance) from engaging in such business until such person, as if he or she were a new applicant for a certificate of registration, shall comply with all of the conditions, restrictions and requirements of Section 2a of this Act and qualify for and obtain a certificate of registration. Upon refusal or neglect to obey the order of the court, the court may compel obedience thereof by proceedings for contempt.
It shall not be a defense in a proceeding before the Department to revoke a certificate of registration issued under the Act, or in any action by the Department to collect any tax due under this Act, that the holder of the certificate is a party to an installment payment agreement under Section 2a of this Act if the liability which is the basis of the revocation proceeding, or the tax that is sought to be collected: (1) was incurred after the date of the agreement was approved by the Department; or (2) was incurred prior to the date the agreement was approved by the Department, but was not included in the agreement; or (3) was included in the agreement, but the taxpayer is in default of the agreement.
35 ILCS 120/2b