A 2006 audit showed federal, state and local governments are among the biggest employers of the half-million persons in the U.S. illegally using "non-work" Social Security numbers – numbers issued legally, but with specific instructions that the holders are not authorized to work in the U.S.[Bush hit over jobs for illegal workers, August 23, 2007 ]
This is something that can and should be cleaned up quickly. Now, once again, we need to think about how to expedite that return home of these illegal immigrants to decent jobs and living conditions.
There also really ought to be a managerial shakeup in the governmental agencies involved in the practice of illegal employment. I doubt sufficient laws are on the books to handle this situation—but that can be changed.