And speaking of shouting ‘Fish!’ brings me to the less elegant language used by a claimant in the case of Duncan v Fujitsu Services LTD 2025, and an employer’s response to an employee with ADHD and ASD sending sending inappropriate and highly offensive online message.

Mr Duncan was employed by Fujitsu Services LTD from September 2017 as a Graduate Trainee and later promoted to Software Developer until he was dismissed for gross misconduct in April 2021. From the start of his employment, managers at FSL were aware that Mr Duncan had Attention Deficit Hyperactivity Disorder (ADHD) and Autistic Spectrum Disorder (ASD) and accepted that these amounted to a disability under the Equality Act 2010.

Mr Duncan brought a grievance which was dismissed in January 2021. Part of Mr Duncan’s evidence for his grievance consisted of logs of messages on Slack, a software platform licensed by FSL for its employees to communicate with each other. The logs included messages between Mr Duncan and two other colleagues, Mr Welek and Miss Shelton, which contained inappropriate and offensive language, including threats of violence and multiple uses of foul language.

FSL investigated all three employees. Following the disciplinary procedure, Mr Welek was dismissed without notice and Miss Shelton received a final written warning. Mr Duncan was invited to a disciplinary hearing in March 2021, he subsequently emailed the week prior to this saying he would not be able to attend but implied that the hearing should proceed in his absence. The disciplinary manager requested further information regarding Mr Duncan’s disability and a copy of the Occupational Psychologist’s report; however, he did not send a copy or engage further in the disciplinary process.

In April 2021, Mr Duncan received the outcome letter which dismissed him without notice. He appealed this decision but subsequently failed.

Mr Duncan then filed claims for unfair dismissal and discrimination arising from disability to the Employment Tribunal.

The claims failed. The ET found that although some of the offensive messages could have arisen from Mr Duncan’s disabilities, FSL’s actions in dismissing Mr Duncan was justified as a proportionate means of achieving legitimate aims of preventing the use of threatening language, harassment and other behaviour that may lead to a hostile environment, and threats of violence against colleagues.

Mr Duncan then appealed the decision to the Employment Appeal Tribunal.

He argued that the reasoning for the offensive messages was due to his frustration at the way FSL had treated him and the lack of reasonable adjustments implemented. Mr Duncan had not previously argued that his language in the messages was itself because of his disabilities (i.e. that his disabilities caused an "involuntary loss of control of emotion" and he didn't "understand social rules"), so he could not now appeal on that basis.

The EAT dismissed the appeal, going on to find no direct link between Mr Duncan’s language and his disabilities as there was no evidence of this sort of language outside of the Slack messages. The EAT also noted that Mr Duncan has edited the messages when initially disclosing them to FSL, indicating that he was aware of the possibility of FSL regarding the comments as misconduct.

Mr Duncan also argued that the ET erred in analysing whether dismissal was fair, as the ET did not appear to have considered options short of dismissal. The EAT upheld the ET’s decision. The ET had described the comments as “very strong examples of foul language and abusiveness towards colleagues” and determined that Mr Duncan should have been aware of the possibility of FSL finding these messages given they were sent on FSL’s communication platform during working hours. The EAT also noted that there was no evidence of reassurance from Mr Duncan to FSL that his actions would not be repeated. The EAT confirmed that the ET had considered options short of dismissal, but agreed that the FSL’s decision was a reasonable conclusion to reach.

This case highlights the delicate balance between upholding standards of conduct in the workplace and fulfilling obligations under the Equality Act 2010. While employers must make reasonable adjustments for employees with disabilities, this case confirms that such protections do not exempt individuals from accountability for serious misconduct, particularly when behaviour threatens workplace safety or dignity. The ET and EAT judgments reinforce that dismissals can be lawful and proportionate, even where disability is a contributing factor, provided employers act reasonably, follow a fair process, and are clear in their legitimate aims.

It serves as a vital reminder for organisations to maintain robust policies, ensure managers are trained in handling complex disability-related issues, and document decision-making carefully to withstand legal scrutiny.