Legal Question in Civil Rights Law in California

It is not against the law, but before being questioned yo could file a motion in limine, or ask the judge, to not allow such questions as they are irrelevant [in some situations your status if a valid issue]. If the attorney already did so, there is nothing you can do about it.

A party's immigration status is irrelevant to a civil case; and if a lawyer were to attempt to raise the issue in court, he or she should be quickly shot down by the judge. There is a Court of Appeal case in which the trial court judge was admonished for allowing an attorney to make improper references to a party's immigration status, for example by saying that illegal immigrants are less credible or more likely to file bogus lawsuits than are other people. The lawyer for the party should file an appropriate "motion in limine" excluding any mention of the party's immigration status at the trial.

Here is the Court of Appeal opinion in Hernandez v. Pacius:

http://caselaw.lp.findlaw.com/data2/californiastatecases/g029961.pdf