It is illegal for U.S. employers to hire or recruit or refer for a fee for employment any foreign national who is not authorized to work in the United States. Moreover, an employer must "verify" that all new hires employed after November 6, 1986, are authorized to work in the United States through the "I-9 employment verification process".

The I-9 process was amended in 1990 in an effort to deal with "document abuse". This is where employers request more documents than is required under the law and/or reject acceptable documents. The law was again amended in 1996 by reducing the number of documents that can be used to prove that a new hire is authorized to work in the U.S.; by providing employers with a "good faith" defense against technical paperwork violations; by providing some protection for employers who are part of multi-employer associations; by broadening the government's investigatory authority and by creating additional penalties for violations of the law.

It is important to note that the federal government uses the I-9 verification process as an easy means to impose civil penalties on companies. It is, therefore, important that all companies establish and implement an I-9 verification process. Part of this process is for a company to undergo regular audits of its I-9 records to determine whether they are in compliance, and to take actions to bring themselves into compliance before a government inspection.

WARNING: An employer must be careful to conduct I-9 verification for all employees hired after November 6, 1986. Inconsistency or selectivity in deciding which current employees should undergo verification might result in the commission of an unfair immigration-related employment practice.