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Do you have to excuse poor behaviour from an employee with a mental health problem?

That was the issue the tribunal had to decide in the case of Muir v Astra Zeneca UK Ltd.


Dr Muir started working for Astra Zeneca in 1998, most recently as an associate principal scientist. He suffered from occasional bouts of stress that, over time, progressed to anxiety and depression. His managers knew that he had ongoing mental health issues and could become stressed and anxious at work. Some of his colleagues and managers referred to him as being a ‘Jekyll and Hyde’ character.  

Dr Muir was appointed the technical lead on project in 2020 and worked with a number of scientists from other teams. He didn't feel that some of his colleagues were pulling their weight and this increased his stress as the project moved towards the planned deadline for completion. Three key meetings took place on 4 June, 9 and 30 of July between various members of the project team. Three scientists spoke to their line managers about Dr Muir's behaviour during the first two meetings. They raised informal concerns about his poorly worded emails, raised voice and difficulties working together which, they said, impacted on the project. Despite this, the relevant line managers didn't intervene, even though Dr Muir had asked for support.  

The investigation

Even though there were no written complaints against Dr Muir, a senior manager notified HR of ‘potential bullying and harassment in the workplace’ by Mr Muir. This set in motion a formal process. HR appointed an investigator. He decided to investigate the allegations under the company Employee Improvement Policy (which was akin to a disciplinary procedure) rather than its Employee Concerns Policy (which focused on problem solving).  

Dr Muir wasn't immediately told that he was being investigated and, oblivious to concerns regarding his previous meetings, had a further meeting on 30 July with colleagues working on the project. The meeting was ‘extremely difficult’ and ‘took a similar form to the earlier meetings which gave rise to the investigation’. 

The disciplinary hearing

The investigator completed his report and recommended that disciplinary action should be taken against Dr Muir. He was invited to a disciplinary meeting and, despite the fact he was a long-standing employee with an unblemished record, he was dismissed for gross misconduct. The disciplinary decision maker (B) said that Dr Muir's behaviour towards colleagues was ‘unacceptable’ and ‘intimidating’ and met the definition of bullying and harassment. B said that he didn't think that Dr Muir would be able to control himself from repeating similar behaviour, in part, because he found it difficult to ‘stay calm’ during the disciplinary process. He didn't accept that Dr Muir's mental health problems excused his behaviour. Dr Muir appealed. 

The appeal 

C was appointed to hear the appeal. She took the unusual step of speaking to B to obtain background information regarding the disciplinary hearing and the technical aspects of the work Dr Muir was doing. B gave her an overview of his findings. 

C chose to review all the evidence again. During the hearing, Dr. Muir explained his long history of mental ill-health and emphasised that he had not received any workplace support to manage these issues. He also provided a comprehensive medical report which highlighted his ongoing battles with anxiety and depression and his long-standing susceptibility to stress. It explained that he adopted coping strategies (such as taking on extra work) which intensified his view that colleagues were not contributing effectively or sufficiently. The report further noted that Dr. Muir might not be aware of how his behaviour was perceived by his colleagues.

C rejected the appeal and Dr Muir brought claims of disability discrimination, unfair and wrongful dismissal.

Decision of tribunal

Dr Muir succeeded with all of his claims. 

Discrimination arising from disability

The tribunal accepted that Dr Muir was ‘overly forceful’ in the manner in which he had expressed himself. However, this was something beyond his control and arose as consequence of his disability. As he had been dismissed for this, the tribunal then had to consider whether that response was a proportionate means of achieving a legitimate aim. It accepted that having a safe environment where employees followed an acceptable standard of behaviour was a legitimate aim. But Dr Muir's dismissal could not be objectively justified because:

  • the company could, and should have intervened at a much earlier stage (including referring him to OH)
  • its failure to do so allowed the problem to develop
  • it had ignored Dr Muir's request for help
  • it should have prevented the 30 July meeting from taking place, or if that was not possible, taken measures to minimise his mental health issues when dealing with stressful situations, and
  • it should not have taken disciplinary action against him at this stage

Unfair dismissal

In respect of unfair dismissal, the company had failed to properly investigate all aspects of the case - particularly the impact Dr Muir's mental health had on his behaviour when under stress. Whilst it was reasonable for management to take some action against him, it was outside the range of reasonable responses to dismiss him given that it knew about his poor mental health and had failed to offer him any real support. 

It was also wrong for the company to use Dr Muir's behaviour during the disciplinary hearing against him: 

‘Even without taking into account the mental health issues which were not properly addressed during the investigation, it should be appreciated that disciplinary hearings where an employee’s job is at risk can be incredibly stressful. Given what is at stake, some allowance should be made to take into account the impact that this might have on how an employee reacts and great care should be exercised in seeking to use that behaviour as evidence supporting allegations relating to earlier matters where objectively, the same jeopardy did not arise.’

It was also very critical of the meetings between the two decision makers. It said that these were ‘ill advised’ and even if the parties were rigorous in their attempts to avoid any bias the mere fact that they had taken place, without having first consulted with Dr Muir or his representative, ‘gave a clear impression that impartiality was being compromised’. That amounted to an unreasonable failure to comply with the ACAS code and the tribunal said it would uplift Dr Muir's compensatory award by 10%. 

Lessons for other employers

1. Identify risk areas for workplace stress

This should go without saying, but it's amazing how many employers (even large ones like Astra Zeneca with well-resourced HR teams) don't really engage with workplace stress at an early stage. 

Employers are responsible for the health and safety of their workforce. They are required to identify hazards and take reasonable measures to prevent to reduce those risks as part of their usual risk assessments. The duty to take reasonable care to ensure the safety of employees at work extends to mental as well as physical health. Stress should therefore be included in those assessments.

Stress affects people differently – what stresses one person may not affect another. Factors like skills and experience, age or disability may all affect whether a worker can cope.

Workers who work alone are particularly vulnerable to stress and poor mental health. 

Surprisingly, the courts have said that no occupation should be regarded as intrinsically dangerous to mental health than any others. But there is emerging evidence that some roles do cause staff regular stress and burnout.

2. Spot common signs of stress

Individuals may have high levels of sickness or other absences, display mood swings, become withdrawn, lose their motivation and confidence, exhibit emotional reactions such as becoming tearful, sensitive or aggressive.

3. Act promptly

Don't bury your head in the sand and hope that the problem goes away. Make sure that your managers know how to handle sensitive or potentially difficult conversations with the staff they manage and can access support and guidance. 

Find out what is causing the stress, whether the employee has an underlying medical condition and what adjustments you can make to alleviate it. Occupational health may be able to assist with this.

4. Dismissal should (usually) be your last resort

If you recruit someone suffering from a mental illness or become aware that they are developing a mental illness, you will need to make some allowances for the condition when judging their performance or behaviour. If it falls below acceptable standards, you can take action against them. But, you shouldn't dismiss them without properly considering alternatives and mitigation first. Generally, you will be expected to warn the employee and consider what steps you can take to support them. 

While stress itself is not a disability, it can lead to anxiety and depression and exacerbate other conditions. If the employee has a disability, consider what reasonable adjustments you can make so that they can continue to work, or return to work.

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