You need a new member of staff. Your job advert has avoided discrimination in its wording and placement - no longer should you see phrases such as "minimum ten years' experience" or ads placed where only a particular group of people will see them. You've made a shortlist of likely candidates, and you're now at the interview stage.

You probably know the questions you'd like to ask, but which ones are legal? Can you ask about people's families, or their religion? Is it OK to ask them their age? Don't know? If you're responsible for conducting interviews for your organisation, you need to gen up - fast!

The various, and many, laws (see the box below) are all intended to guard against direct or indirect discrimination, and victimisation. Because of this, interviewers leave themselves and their firms open to prosecution if they ask the wrong questions.

Most of us know that direct discrimination involves making decisions based on a person's colour, sex, religion, etc. But what is "indirect" discrimination? This manifests itself in questions which refer to the applicant's age, length of service or experience, whether currently employed, intentions to have children, etc. An applicant is said to be victimised when the interviewer takes account of the fact that the interviewee has brought previous racial or sexual discrimination charges against an employer.

Positive discrimination is also illegal, although positive action is not, where targets for employing more of a certain group of people act as a method of eliminating historic imbalances in the gender, ethnicity, disability, etc, of staff.

To avoid bias, interviewers should focus on the abilities and aptitudes of each applicant based on what's needed to fulfil the job specification. It sounds simple but it's difficult to avoid subjectivity when someone you like doesn't have the right skills - or alternatively when someone you don't get on with has exactly the right qualities and qualifications.

The best way to be fair is to use the same questions to structure each interview and be sure that each interviewee is treated, as far as possible, in the same way. Follow-up questions can then be tailored to individuals to elicit clearer or more detailed information. Each applicant should then provide information which can be compared when you make your decision.

Subjects to avoid

Personal questions are strictly out unless the job is one where the applicant will have contact with children or vulnerable adults. The applicant's name, address and contact details are all the personal details normally required.

Specifically you should avoid asking about marital status, family, religion, sexual orientation or membership of a trade union. Asking an interviewee about their family, for example, may be interpreted as a bias against employing particular female staff; questions about retirement may seem to militate against mature applicants. Matters such as unsocial hours or extensive travel should be discussed objectively without detailed questions about domestic arrangements.

You may ask questions about a disability if by doing so you show that you're seriously considering offering the applicant the position. The applicant can then discuss how they could cope with the job and the interviewer can consider how the working environment can be adapted to suit the new employee's needs.

Working with children

If your new employee will be working in an area where they have contact with children or vulnerable adults then interview questions are expected to probe far more deeply. The Protection of Children Act 1999 states that anyone who has regular contact with children in the course of their job - school secretaries, for example - must be screened to protect the vulnerable. Under these circumstances interviewers are expected to ask questions about the applicants' background, personal circumstances, experience and possible criminal record. All applicants must be treated equally, and impartially.

Personal checks on the applicants' background are also required as part of the recruitment process (see disclosure.gov.uk). In these cases it is vital that the interviewer is seen to be pursuing a professional line of enquiry, and not straying into unnecessarily intrusive or prying questions.

Sharing the load

Involving more than one person in an interview is often a good idea, particularly if they're different sexes, races, or ages, etc. Each can then make sure that there is no discrimination and a joint decision is less likely to be subject to bias - and more likely to be seen to be fair.

The interviewer(s) who are not immediately asking questions can also take notes. Such informal minutes should record what was said in the interview and how the selection decision was made, but should not include the interviewer's impressions, beliefs or opinions.

Unsuccessful applicants often ask for feedback after interviews and your written records should help you to be constructive. Notes are also helpful if the worst happens and you're called to an employment tribunal. The complainant also has the right to have copies of notes taken at interview but good written records will help you to justify your actions.

Recruiting the right staff is vitally important. Not only are you choosing a future colleague but also directly influencing the success of your firm. Ensuring that you assess all applicants using the same criteria is not only a legal requirement but also a shrewd business move.