Under IRCA, employers may hire only persons who may legally work in the U.S., i.e., citizens and nationals of the U.S. and aliens authorized to work in the U.S. The employer must verify the identity and employment eligibility of anyone to be hired, which includes completing the Employment Eligibility Verification Form (I-9). Employers must keep each I-9 on file for at least three years, or one year after employment ends, whichever is longer.
That is from the 1990 version I believe and no, I don't pretend to know much about all the ins and outs of the immigration and Customs acts and laws. Wish I did understand these issues better but I am to dumb to sort through all the crap they write and decipher just what they are trying to say. So I post what I feel, not claiming that it is right.
By the way, NAPA is a great place to lecture about this as there is plenty of wine to keep you laughing.
Ron