Avoid Illegal Interview Questions
Finding the right thing to say on an interview is difficult, but it is also tricky to conduct the interview and not ask illegal questions. Questions about race, color, sex, religion, national origin, birthplace, age, disability or marital status are illegal to ask in an interview.
Most employers who ask these questions are not trying to discriminate or make you uncomfortable. They simply don’t know that they're not allowed to ask. Unfortunately, this leaves the interviewee in a strange predicament; either he or she can answer the offending question or refuse to answer, in which case he or she will seem contrary to the interviewer.
One solution is to be prepared and answer inappropriate questions with answers that are related to the position. For example, if asked if you're a U.S. citizen, you can respond that you're legally authorized to work in the United States.
You can also try to crack a joke and ask your interviewer why he or she is asking the question. The interviewer will most likely revise the question to make it more precise and appropriate or drop the question and move on.

Comments
Under what catagory does citizenship fall? race, color, sex, religion, national origin, birthplace, age, disability or marital status? I wish the example used related to the age question. That isn't easy to answer. "Old enough to know better than to answer that question?
How about telling the truth
Race, color and sex are usually clear and don't need to be asked. Religion has never been asked of me, except on surveys and usually has an option of not answering. National origin can be a country, which doesn't really say anything. Birthplace as well, unless you say you were born in a car... or a bus, plane, etc. Age is often clear to the eyes, as are many disabilities. Marital status usually doesn't matter. Most of those are legally covered. Weight is not, and should be. Getting snippy (Old enough to to know better...?) is NOT going to get you the job.
I discovered that I know two people that have never met each other but who briefly worked for the same employer. At different times each one told me of having had the same experience of this employer asking them their religious affiliation. The question was not put to them during a job interview but shortly after they had been hired and had been working on the job. Is this illegal or is this a legal loophole since the question was not asked during the actual interviews? Both people were of religions that differed from the religion of the employer and all of his other employees. Within a matter of days after they answered his question pertaining to religios affiliation, he announced that he just wouldn't be able to use them and they were let go. Is this employer skating on thin ice legally or is he well within his legal rights?
Thats Unamerican! but maybe legal. Employers have a right to fire people without any reason in most states. I guess if you know an employer is one of those "Christo facsists" you're better off staying away. Yes, that part is obvious.
It is illeagal to ask your race but the gov does ask and gives them special treatment talk about pseudo liberal fascist
It is illeagal to ask your race but the gov does ask and gives them special treatment talk about pseudo liberal fascist