[kleim]

As an interviewer how would you prove during a trial that by asking these kind of questions you were not intending to discriminate the interviewee?

[fffggg]

One obvious example would be if you had hired the interviewee in question. If so, it would be awfully difficult to demonstrate discrimination against them!

Don't get me wrong, it is a very bad idea to ask these questions. But it is not illegal, strictly speaking.