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He said, she said: dealing with conflicting evidence in workplace investigations


In the second part of our three-part mini-series focusing on bullying, this blog considers the difficulties of making factual findings when the allegations are highly subjective and feel more like a question of perception than facts to be found. The final part will look at providing meaningful and appropriate support to the employee accused of bullying. Read the first part of the series discussing workplace bullying here.

Setting the scene: your job as investigator

You are investigating a serious workplace bullying allegation. You have interviewed both the complainant and the subject of the investigation.

He said:
There have been on-going performance issues with her work. He has had to monitor her work closely and provide consistent but constructive feedback to her. He has done so verbally to keep it informal and in the hope it would be better received.

She said:
From the time she started her new role on his team, his management style has been overbearing. He is passive aggressive, and makes nasty and unprofessional remarks to her about her abilities seemingly to humiliate her. Her confidence has been severely damaged, her mental health is suffering and she cannot continue to work in this toxic environment.

You emerged from each interview believing their evidence entirely. Each of them was credible, sincere, earnest and likeable. This is certainly not uncommon: anyone who has observed an Employment Tribunal case without inside knowledge of the case will recognise that experience of being persuaded by each side as they give their own evidence. However, in the investigation context you usually have wider evidence to rely on: the messages, the emails, the other witnesses. What do you do, however, if none of that sheds any light on who is telling the truth?

How do I decide who to believe?

As part of your terms of reference for the investigation, you should have been provided with guidance on the standard of proof you should use to decide whether there is enough evidence to support the complainant’s allegations. The applicable standard would almost certainly be on “a balance of probabilities”.

What does this mean in practice? It simply means that you consider, on the evidence, that it is more likely than not that a particular fact happened. This does not mean that you need to be absolutely certain or have irrefutable proof to support your decision. It does mean, however, that you need to make a decision one way or the other. 

But these allegations are serious, potentially even career-ending. Surely that means the evidence needs to be even stronger to support a finding against someone?

This is a difficult question, and one that even the courts have struggled with. For example, Lord Nicholls observed in the case of Re H (Minors) (Sexual Abuse: Standard of Proof) [1996] AC 563, that:

“… the more serious the allegation the less likely it is that the event occurred and, hence, the stronger should be the evidence before the court concludes that the allegation is established on the balance of probability”. 

However, that has the flavour of a logical fallacy. Why should it be that serious allegations are less likely to have happened? Perhaps it is right that serious wrongdoing is less common, but it is well established that serious allegations which should be raised often are not due to concerns on the part of the complainant of the potential ramifications of raising a complaint. Raising the standard of proof seems to engineer the system against those who come forward with such allegations (and there are often enough hurdles to prevent that already, without adding another).

The House of Lords in R B (Children) [2008] UKHL 35 rejected Lord Nicholls’ position, and the authorities now do not support the idea of requiring more evidence to prove serious allegations where the standard of proof is the balance of probabilities.

That said, in some cases those instructing the investigator may decide to set a higher standard of proof from the start (for example in a quasi-criminal case, given the serious potential consequences of an adverse finding). While this is unusual, the investigator is absolutely correct to work on the basis of the prescribed standard of proof where it has been set at a higher level. What the investigator should not do, however, is artificially elevate the standard of proof where all that is required is a finding on the balance of probabilities.

How do I approach this in practice?

It should be a rare case where there is genuinely no other evidence that you can rely upon to help you form a view as to which version of events is more likely to have happened. The starting point, therefore, is to take a fresh look at the wider evidence and consider whether it is consistent, or inconsistent, with each version of events. Consider not just the evidence that you do have, but the evidence that you would expect to have if one or the other’s version of events is true. For example, there may be no witnesses able to corroborate either of their versions of events; but that, in itself, might be odd. In our example, she says that he is meant to have made remarks seemingly to humiliate her. You might have expected people to notice that sort of behaviour and so the absence of any witness evidence might, in fact, lend support to his version of events (although it is important to take care with assumptions of this kind).

However, if having considered all the evidence you still feel unable to determine which version of events is more likely, you may need to turn to the burden of proof. The burden of proof is on the complainant, and if that burden has not been discharged then the complaint cannot be upheld. However, in this scenario it is important to be clear regarding the steps you have taken and efforts you have made to attempt to interrogate the evidence and make a finding one way or another, and why you believe that not to be possible.

Investigators can feel an immense sense of responsibility, particularly in sensitive cases where potentially severe consequences can flow from the findings. While it is, of course, important to recognise that responsibility and to carry out an investigation in a diligent manner, keeping the standard of proof in your mind can be a useful tool not only to discharge your duty but also to help assuage some of the pressure associated with being an investigator.

This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Farrer & Co LLP, September 2023

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About the authors

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Charmaine Pollock


Charmaine combines technical employment law advice with commercially minded pragmatism and a strong sense of warmth and empathy. This enables her to work collaboratively with clients (both employers and individuals) to fully understand their needs, and to help them select an approach which best suits their objectives.

Charmaine combines technical employment law advice with commercially minded pragmatism and a strong sense of warmth and empathy. This enables her to work collaboratively with clients (both employers and individuals) to fully understand their needs, and to help them select an approach which best suits their objectives.

Email Charmaine +44 (0)20 3375 7644
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