Illegal Question:

Interviewer can ask questions regarding whether you are able to meet work schedules, or travel for the position. He can ask about how long you expect to stay at a particular job, or with the prospective firm. Whether you anticipate any extended absences can also be asked.

An interviewer can't ask your marital status, if you have children, what your child care situation is, or if you intend to have children (or more children). You cannot be asked about your spouse's occupation or salary. If you choose to answer a question of this kind, a graceful way to answer is to say that you are able to perform all the duties that the position entails.