Disability
[ch 5: page 65]If the employer knows, or should know, that a worker has a disability then they should investigate whether this has a bearing on the conduct or capability in question. Under section 15 of the Equality Act 2010, it is unlawful to treat a disabled worker unfavourably for a reason “arising from their disability” unless objectively justified as “a proportionate means of achieving a legitimate aim”. Unfavourable treatment includes disciplinary action and dismissal:
A wheelchair user was dismissed for gross misconduct after losing his temper and shouting racist abuse because he was frustrated that training had been arranged in a room without wheelchair access. Had he not been disabled, he would not have been upset by the decision and would not have lashed out. There was enough of a connection between the disability and the misconduct to trigger rights to protection under section 15, EA 10. The dismissal was unlawful.
Risby v London Borough of Waltham Forest [2016] UKEAT/0318/15/DM
https://www.bailii.org/uk/cases/UKEAT/2016/0318_15_1803.html
See also the case of City of York Council v Grosset [2018] EWCA Civ.1105 summarised on page 62.