If you're facing an employment lawsuit, don't bother probing into the employee's immigration status during the lawsuit's discovery phase. The EEOC has long held that immigration status is irrelevant to any underlying discrimination claims, and a recent federal court ruling supports this stance.
The case: A female restaurant employee claimed sexual harassment and the EEOC sued on her behalf. During discovery, the restaurant's attorneys asked about the woman's immigration status. EEOC attorneys objected, and the judge agreed to bar any questions designed to elicit whether the woman is in the country legally. (EEOC v. The Restaurant Company)