Five things that will sink your workplace investigation at tribunal

Most workplace investigations don't fail because the wrong conclusion was reached. They fail because of how the investigation was run.

Employment tribunals aren't interested in whether you got the answer right. They want to know whether the process was reasonable. And reasonable, in this context, means something quite specific.

Here are five things I see over and over again in investigations that wouldn't survive tribunal scrutiny.

1. No terms of reference

The investigation starts without anyone writing down what's actually being investigated. The allegations aren't clearly defined. The scope isn't set. The investigator isn't sure whether they're looking into one complaint or three, or whether related issues that come up during interviews are in or out of scope.

A tribunal will want to see that the investigation was focused and structured from the outset. Without terms of reference, it looks like the investigator was making it up as they went along.

2. The investigator wasn't independent

This is the big one for small businesses. The person investigating often has a relationship with one or both parties. They might line manage the person being complained about. They might have been involved in the informal stage. They might just sit close enough to the situation that their neutrality is in question.

Independence doesn't mean the investigator has never met anyone involved. It means they don't have a personal or professional stake in the outcome. In a business with 20 people, that's often impossible to achieve internally.

3. Witness interviews weren't structured

The investigator had a chat with a few people and wrote up some notes. But the questions weren't consistent across witnesses. Key allegations weren't put to the person being complained about. And the notes don't reflect what was actually said, they reflect what the investigator remembered afterwards.

Structured interviews mean preparing questions in advance, putting each allegation to relevant witnesses, and taking notes that are as close to verbatim as possible. It's not a casual conversation. It's evidence gathering.

4. The report doesn't address each allegation

The investigation report is sometimes a narrative. It tells a story. But it doesn't systematically work through each allegation, set out the evidence for and against, and explain how the investigator reached their finding on each one.

A tribunal judge reading the report needs to be able to follow the logic. If the report says "on balance, the allegation is upheld" but doesn't explain what evidence supports that and what evidence contradicts it, it looks like the conclusion came first.

5. The same person investigated and chaired the hearing

This is more common in small businesses than anyone admits. The person who ran the investigation also presents the findings at the hearing, or worse, chairs the hearing and makes the decision.

The ACAS Code expects separation between investigation and decision-making. When the same person does both, it creates the impression that the outcome was predetermined. A tribunal will look at that and ask whether the employee ever really had a fair hearing.

What to do instead

If your business doesn't have the internal setup to run an investigation that meets these standards, that's not a failure. It's just the reality of being a small organisation. Bringing in someone independent to investigate means the process holds up, your people feel heard, and you've got a defensible paper trail if things escalate.

I run independent workplace investigations for businesses across Sheffield, Leeds, Manchester, Bradford, Hull, Liverpool, Nottingham and Derby. If you've got a situation developing and you're not confident the process is right, it's worth having a conversation early. These things are always easier to get right at the start than to fix halfway through.