Ill. Admin. Code tit. 56 § 5220.500
An employer, employment agency or labor organization may not require a job applicant to disclose his or her national origin or ancestry, unless it can show a bona fide occupational qualification. Likewise, an employer, employment agency or labor organization may not require a job applicant to disclose his or her citizenship where a citizenship requirement would have the purpose or effect of discriminating against a person on the basis of national origin. In deciding whether a citizenship requirement is having the effect of discriminating against individuals on the basis of national origin, the Human Rights Commission and the Department of Human Rights will consider whether the percentage of the employer's workers of a particular national origin group is similar to the percentage of qualified workers of the same national origin group found in the geographical area from which the employer draws his or her workers. An analagous analysis will be applied to charges brought against employment agencies and labor organizations which have citizenship requirements. Nothing in this section shall be construed to require an employer, employment agency or labor organization to employ individuals who are not able to lawfully work in the United States (See Section 5220.600) . It is not a violation of the Act for an employer, employment agency or labor organization to uniformly inquire of all applicants whether they are able to lawfully work in the United States.
Ill. Admin. Code tit. 56, § 5220.500