Here is an example from a coworker from a previous job:
A candidate came in for an interview. It was quickly apparent he slipped by the phone screen, as he brought code examples in MS Word documents.
During the interview, he claimed to be the second coming of Christ. The interviewers (my coworker and his boss) wisely said nothing in response and moved on to a different topic.
A few weeks later, he initiated a lawsuit claiming we did not hire him due to religious discrimination. It was a nuisance suit and dismissed as such, but a good reminder that interviews are business transactions, not chats between friends.
A very short list of questions that would potentially be cause for a lawsuit:
- religion
- family (i.e. do you have kids)
- culture (aside from work behaviors)
- personal background
- race
- health (nothing at all can be said short of stating that accomodations can be provided if necessary, assuming the job does not have physical requirements such as lifting or driving).
There are more, but I think this should give you a decent idea. The point is not that everyone is litigious, but rather that there are people who are, and you must act as a representative of the company during an interview.
Personally, I would not expect someone to take an active role in interviewing unless they had some training or I knew they were already experienced- partly for these reasons, but more so because it is not an easy skill. I have suffered through bad interviews at companies, and wouldnt want a company I work for to make those mistakes.