Any employer who claims to be honest, knows damned well they can go to the SS Web Site and confirm any Employee's legal status to be using their SS number.
Excerpted from: http://waysandmeans.house.gov/hearings.asp?formmode=printfriendly&id=4708
"To further increase the ease and convenience of verifying employee SSNs, SSA developed the Social Security Number Verification Service (SSNVS), which is an internet option that permits employers to quickly verify the accuracy of employees names and SSNs by matching the employee-provided information with SSAs records. SSA expanded this service to all employers in June 2005. We processed over 25.7 million verifications for over 12,000 employers in 2005. "
"The information the employer submits to DHS is sent to SSA to verify that the social security number and name submitted match information in SSA records. SSA will also confirm US citizenship, thereby confirming work authorization; DHS confirms current work authorization for all non-citizens. DHS will notify the employer of the employees current work authorization status. This program is also available to all employers, subject to available resources."