When is stress a disability?

There is considerable confusion over the status, for legal purposes, of an employee who is off with work-related stress. Is it a disability? Does it engage disability legislation? The employment appeal tribunal has stated categorically that it does not. Stress is not impairment for the purposes of disability discrimination. That does not mean that an employee may not sue for damages as a result of stress caused by the employer's negligence, but it does mean that stress in itself is not something that there is, for example, a legal duty to make 'reasonable adjustments' for.