Under IRCA, employers are required to ask for documents establishing identity and authorization to work in the United States. There are several combinations of legally acceptable documents from which they can choose. These combinations are listed on the back of the I-9 form, which must be completed for every employee, regardless of national origin, including U.S. citizens. As long as the documents presented prove identity and work authorization, and are included in the list on the back of the I-9 form, they are acceptable. Employers cannot prefer one document over others for purposes of completing the I-9 form.
Not all authorized aliens carry the same documents. Employers may not request more or different documents than are required to verify employment eligibility, reject reasonably genuine-looking documents, or specify certain documents over others with the purpose or intent of discriminating on the basis of citizenship status or national origin. For example, not all aliens who are authorized to work are issued green cards. As long as the documents are allowed by law, appear to be genuine, and relate to the person, they should be accepted. To not accept such documents is illegal.
These protections prohibit discrimination against U.S citizens as well as all individuals authorized to work in the United States.