Generally speaking, there is no hard and fast rule which says all interviews must be conducted face to face during a workplace investigation.
Before you decide, however, that you now simply never need to conduct another face-to-face interview again with any future investigation participant, here are a few factors to consider, when conducting a telephone or video interviews, using video meeting platforms like Skype or Zoom.
What does your policy say?
It’s always good, for a host of reasons, to follow what your complaint-handling policies promise. It may not actually cover into this level of specificity (or indeed, use words of obligation), but if your complaint-handling policy states “every investigation participant is entitled to a face to face interview with the investigator”, then it is important to follow your policy. The importance of this is underlined in the case of Romero v Farstad Shipping (Indian Pacific) Pty Ltd  FCAFC 177.
Capacity to participate
If someone is unable, say due to a workplace injury, to physically attend the workplace or suitable interview location, then a reasonable adjustment you might offer could be a telephone or video interview.
In these circumstances, offering such an option would therefore enable participation and demonstrate that you were being inclusive towards all participants. You would also be considering and applying the principles and best practice set out in your EO policies.
Do always check with the individual whom you are interviewing, in advance if possible, that the designated time is a good time to conduct the interview. Just as you don’t want an interviewee in a face to face interview to be distracted or unable to focus on your questions because they are, for instance, expecting a call, or looking after a sick child, exactly the same variables apply with the phone or video interview.
Make sure that they are able to have your full attention, and that they are in a discreet and private location.
As you need to do when conducting any interview, make sure that the individual being interviewed is fit to be interviewed, understands questions put to them and has a truly reasonable opportunity to respond.
If your telephone or video call is international, then do take into account what time it is (both for you and the interviewee). Tiredness is not helpful to providing detailed recollection and responses, or for you as the interviewer, in spontaneously formulating a clear and cogent series of questions.
As acknowledged in a previous post, you also need to ensure that anyone you are interviewing is not drunk or drug-affected. This may be potentially harder to gauge if you are running a telephone interview. Specifically, in Roger Garrett v Shamrock Holdings  AIRC 832, the investigator was aware that the respondent was drunk during their first interview over the telephone. Whilst the investigator at that time then also informed the respondent that he would have a further discussion when sober, this never then took place.
Procedural fairness still applies!
Make sure that you do not cut any corner of procedural fairness.
Any interviewee has the right to a support person, regardless of whether the interview is in person or by a telephone or video call.
If you are offering a telephone or video interview to one person who is otherwise able to attend for an interview in person, then fairness would dictate that you may need to offer this same option to all.
It is also useful to make sure that you do not treat telephone or video interviewees differently from those whom you interview in person.
For example, if your telephone interviewee says that they need the questions you will ask them in advance, do explore what the rationale is behind this request. If they have an impairment which is affecting their work capacity, they are on sick leave, and are having trouble concentrating as a result, then it may be part of reasonable accommodation to provide such questions. As a general rule, however, it is not fair to treat interviewees differently without a solid and sound basis for doing so.
Limitations to “remote interviews”
Building rapport with an interviewee in turn build trust, and that, in turn, leads to more comprehensive information being provided. Even if you are using internet-enabled video platforms to conduct an interview, the best way to build rapport is through a face to face interview in person.
Be aware that if you are conducting a remote interview that you will need to work much harder to build rapport and really listen and observe how the individual is communicating with you. You will have less available visual cues available to you in order to interpret what might be the context or meaning of information provided.
At the same time, always remember that relying on body language is not a reliable indicator of a person’s truthfulness or otherwise.
In conclusion, much as our instantaneous, communication-crazed culture thrives on the benefits of that technological miracle, the “telling bone” (to quote Catweasel), do take care when using it to conduct your investigation interviews. Romero v Farstad Shipping (Indian Pacific) Pty Ltd  FCAFC 177
About Grevis Beard
Grevis Beard, Worklogic Director, is a highly experienced and widely respected author, dynamic speaker and trainer, and workplace investigator. Grevis speaks knowledgeably and diplomatically on how to resolve workplace conflict, manage people risk and build a positive culture at work.