The University of Otago requires candidates to provide three referees. Ideally, one of these referees should have supervised, or been senior to them, in their current or most recent employment. At least one of the other referees should have supervised, or been senior to them, in previous employment.
People often prefer that their current employer or manager is not made aware of their intention to leave, so have not asked their permission to use them as a referee. The candidate's career opportunities with their current employer could be jeopardised by an enquiry.
If a candidate hasn't included their current employer as a referee, you should discuss this with the candidate and assure them that the referee would not be contacted until the candidate gives permission. Tell the candidate that if they are the preferred candidate at the end of the selection process, you will need a reference from their current employer before any offer can be made. If they are the preferred candidate, ask for the referee name and obtain the candidate's agreement to contact them.