How to run a fair workplace investigation in NZ

A workplace investigation establishes the facts before an employer decides on any disciplinary action. In New Zealand it must meet the principles of natural justice: clear allegations, a genuine opportunity to respond, an impartial investigator, and open-minded consideration. A flawed investigation can sink an otherwise justified decision.

Reviewed 15 July 2026Hello Monday consultants8 min read

When to investigate

Investigate whenever you need to establish facts before forming a view, for example after a serious allegation, a complaint of bullying or harassment, or suspected misconduct. The point of an investigation is to find out what happened, not to confirm a conclusion you have already reached.

The principles of natural justice

Natural justice is the obligation to act fairly when making decisions that affect an employee. In an investigation it means:

Clear allegations: tell the employee the specific allegations, when and where they are said to have happened, and what standard or policy is said to have been breached.
A right to respond: give them adequate time to prepare, access to the relevant evidence, and a genuine chance to put their side.
An impartial investigator: where possible, the person investigating should be independent and open-minded.
Genuine consideration: actually weigh the employee’s explanation, rather than going through the motions.

Running the investigation

Define the scope and allegations

Set out in writing what is being investigated and the specific allegations, so the process stays focused and fair.

Gather evidence and interview

Collect relevant documents and interview those involved. The employee under investigation should be able to bring a support person or representative to any interview.

Keep investigation and decision separate

Where you can, keep the fact-finding separate from the person who will decide any outcome. This protects impartiality and reduces the risk of a predetermined decision.

Document everything

Record the allegations, the evidence, the employee’s response and your findings. Good documentation is what makes a decision defensible.

Why process is where employers lose

A failure of natural justice is one of the most common reasons disciplinary decisions are overturned in New Zealand. Even where misconduct is proven, an employer can lose if the investigation was unfair. From 21 February 2026 a minor procedural slip alone should not make a dismissal unjustified if the employee was treated fairly overall, but a genuinely unfair investigation still creates real risk.

Frequently asked questions

What is natural justice in a workplace investigation?

Natural justice is the duty to act fairly. In an investigation it means giving the employee clear allegations, a genuine opportunity to respond with access to the evidence, an impartial investigator, and honest consideration of their explanation before any decision.

Does the investigator have to be independent?

Where practical, yes. An impartial or independent investigator protects the fairness of the process. For serious or sensitive matters, employers often appoint an external investigator to keep fact-finding separate from the decision.

Can the employee bring a support person to an investigation meeting?

Yes. As part of a fair process and the duty of good faith, employees should be able to bring a support person or representative to investigation and disciplinary meetings, and should be told of that right in advance.

What happens if a workplace investigation is unfair?

An unfair process can make a resulting disciplinary decision unjustified, even where the misconduct itself is proven. Procedural failures are one of the most common reasons employers lose personal grievance claims.

This guide is general information about New Zealand employment law, not legal advice. Employment situations turn on their facts, and the law can change. For advice on your situation, get in touch before you act.