Employers are being warned to tread carefully when dealing with poor performance following a landmark decision in the Employment Appeal Tribunal.
In judgment on a case involving the Heinz food company the EAT ruled that employers can be guilty of disability discrimination even when they do not know that an employee has a disability.
They can also fall foul of the law when the employee is unaware of their own disability.
Making the judgment the court gave the example of a typist who constantly makes spelling mistakes. If he or she was sacked for poor performance and later discovered they had dyslexia, the employer would be open to a disability discrimination charge.
Paul Nichols, employment law partner at Dibb Lupton Alsop, said the judgment is "very important" as it reverses the current situation whereby employers are protected if they do not know an employee is disabled.
The important issue is whether or not the employee displays symptoms of a disability, he said.
"Employers do need, before dismissing anyone on the grounds of capability, to really consider whether the disability act could apply. If they don't they can assume they could be vulnerable to substantial claims," he said.
The Heinz v Kenrick case involved employee Malcolm Kenrick who worked on the production line at the Heinz plant in Wigan. He was dismissed after taking several months off sick. He had complained that he was ill but the company doctor was unable to diagnose his condition.
He was later diagnosed as having chronic fatigue syndrome, or ME, by an immunologist.
Alan Lewis, head of employment law at Keogh Ritson, who represented Kenrick, said the condition affected his concentration, mobility and ability to carry out every day tasks - all symptoms of disability under the Act.
"This puts the onus on employers to investigate very thoroughly reasons for poor performance and if necessary to take medical advice," said Rob McCreath, employment partner at Eversheds, London.
By Dominique Hammond