Use an external workplace investigator when the allegations are serious, could lead to dismissal, involve senior people or HR, or when nobody inside the organisation is trained, genuinely independent and available. An external investigator reduces the risk of actual or perceived bias and produces findings that are more likely to withstand scrutiny if a decision is challenged.

Which situations usually call for an external investigator?

Serious allegations. Sexual harassment, violence, fraud, theft, corruption or other conduct that could amount to serious misconduct.
Possible dismissal. Findings that may lead to termination are the most likely to be tested before the Fair Work Commission.
Senior respondents. Complaints about managers, executives, the CEO or board members, where internal staff report to the person accused.
Conflicts of interest. Complaints that involve HR, the person who would normally investigate, or close colleagues of the parties.
Multiple complainants or a pattern. Several related complaints, or allegations of a culture problem in a team.
No internal capacity. Small and medium employers often have nobody trained in investigations, and investigations are time-intensive.
Public interest disclosures. Whistleblower reports can carry extra legal obligations and confidentiality requirements.
Small communities. In regional towns and remote sites, internal investigators often know the people involved outside work.

Why does independence matter so much?

Procedural fairness has two core rules. Queensland’s Public Sector Commission guide on workplace investigations puts them this way: a person must be given sufficient information to know the case against them and an opportunity to respond (the hearing rule), and a person is entitled to a decision by a disinterested and unbiased decision-maker (the bias rule). Those principles come from public sector administrative law, but they are widely treated as good practice for any workplace investigation.

An internal investigator with a reporting line to the respondent, a friendship with the complainant, or a stake in the outcome can be accused of bias, even if they act in good faith. That accusation alone can undermine the findings.

What happens when an internal investigation is tested?

If a dismissal is challenged as unfair, the Fair Work Commission must consider matters including whether there was a valid reason related to the employee’s capacity or conduct, whether the employee was notified of that reason, and whether they had an opportunity to respond (Fair Work Act 2009 s 387). An employer’s belief that misconduct occurred is not enough; the Commission decides for itself whether the conduct happened.

In Hatch v WesTrac Pty Ltd [2020] FWC 5729, the Commission found a dismissal unfair after identifying flaws in the employer’s investigation: key witnesses were not spoken to, untested written statements were relied on, and assumptions were not put to the employee for a response. See investigation findings and unfair dismissal.

Is an internal investigation ever enough?

Yes. Low-level, straightforward matters can often be handled internally by a trained, independent manager or HR officer, or resolved informally. The right response should be proportionate to the seriousness of the allegations. A middle path is to run the investigation internally with external guidance on the allegations, process and report.

Questions to ask before deciding

Could the outcome include dismissal or a serious warning?
Does anyone who would investigate report to, work closely with, or have a personal connection to the parties?
Does the matter involve sexual harassment, violence, fraud or a whistleblower report?
Do we have someone trained in investigations who can give it the time it needs?
Would we be comfortable defending this process before the Fair Work Commission or a court?

If the answer to any of the first three is yes, or to either of the last two is no, an external investigator is worth considering.

How BION Partners can help

BION Partners provides independent workplace investigations for employers, from informal complaints to complex formal matters, and can also advise your team if you decide to investigate internally. For a review of your organisation’s overall process, see the BION Audit.

General information only. This page explains the law in general terms and is not legal advice. For advice about your situation, speak with a lawyer.

Sources

Checked 22 October 2026. Laws and guidance change; check the source before relying on it.

When should an employer use an external workplace investigator?