Ever since the McCarthy era, the subject of what a person in authority is allowed to ask during a job interview has been at issue. While a hiring manager usually doesn't inquire whether a candidate is affiliated with fringe political groups, other invasive questions may well be asked: "Are you married?" "How many children do you have?" "What is your native language?"

Conducting a job interview seems easy when you first think about it. For a hiring manager, it is an opportunity to get to know a candidate and assess that person's skills and experience. The issue under current law is just how much are potential employers entitled to know? If a candidate is a Java programmer, for example, the gist of what a potential employer needs to know is whether the candidate is a good programmer, how much experience that person has and whether he or she can be relied upon when critical situations arise.

If you run a dot-com and are burning through your first round of venture funding, you want to know whether a candidate will be able to work an ungodly amount of hours. It is legitimate to present candidates with a realistic picture of the workload and ask them if they can handle it. But can you make an assumption that married people over age 30 would be less willing to put in the hours, and then ask about marital status during the interview? Absolutely not.

What Can Employers Ask?

Here's a rule of thumb for hiring managers: If it's not job-related, don't ask. Not even to be conversational. If a candidate sees a picture of your kids on your desk and asks how old they are, that individual is probably trying to express friendliness -- usually a good quality in a candidate (unless you're hiring a collection agent). You can take these situations as cues to talk about your own kids, but you still can't ask interviewees about theirs unless they volunteer the information first.

The Equal Employment Opportunity Commission spells this out in its "Best Practices" document: "With respect to employment applications, inquiries should be job-related. Questions that limit any protected class of employees should be avoided. Employment application forms should be carefully reviewed for compliance with federal and state laws."

The best option for a hiring manager is to have a list of preapproved questions that you know are legal. Some automated hiring systems generate a customized list of questions for the hiring manager to ask each individual candidate, based on the resume and other input. Unicru's Smart Assessment technology, for example, is a decision support system that serves as a hiring guide to managers by providing a list of questions that are guaranteed to be legal. "We've had some employers who bought our system specifically for that reason, because they were getting EEOC complaints and they had lawsuits," says Bob Gregg, CEO of Unicru. "We've not only demonstrated our system as 100% EEOC-compliant, it also takes the discretion out of the hiring manager's hands as far as what kind of questions you're going to ask."

What Candidates Need to Know

As a job candidate, what do you do when an interviewer asks an inappropriate question? First, if an illegal question is posed to you, this should raise a red flag. "We usually tell people that they need to decide how much they want the job, because sometimes it's a bad sign when they ask illegal questions," says Ann Roberts, director of counseling services for Women at Work, a job-resource center based in southern California. Being asked such questions may or may not be a bad sign, depending on whether they were raised out of ignorance, or out of an attempt to discriminate.

Cynthia Nelson, from Los Angeles-based high-tech recruiting firm Bridgegate, advises candidates to take it one case at a time. If a question or comment about children pops out, "maybe they're just trying to establish a common ground, they're trying to bond with you," says Ms. Nelson. In those less-than-blatant cases, she says, you can deflect a question and change the subject. But if the interviewer persists, Ms. Nelson sees that as another matter, which goes back to the issue of whether they're willfully being noncompliant.

Ms. Roberts agrees that potentially offensive questions, even though they may be unintentional, must be handled with a certain amount of finesse. Instead of directly answering the question, Ms. Roberts suggests addressing the issue behind the question. A query about children may be an attempt to find out about whether you will be available to work as needed. "You can say, 'If you're concerned about my availability, I can assure you that I'm available during the times we talked about as well as overtime,' and then continue talking about your experience and skills."