The claimant in O'Brien v Bolton St Catherine's Academy, director of Learning ICT, was assaulted by a pupil at the school where she worked, suffering injury and an acute stress reaction (a disability). She had been off sick for 14 months when, as there was no immediate prospect of return, her employer decided to terminate her employment. Although she produced new medical evidence at the internal appeal hearing and asserted that she was fit to return to work full-time, the dismissal decision was confirmed.

The Tribunal found that the claimant had suffered discrimination arising from her disability because the employer had failed to show objective justification; in other words that the dismissal was a proportionate means of achieving what were accepted to be legitimate aims – running the school efficiently, providing a good standard of teaching and reducing cost. The employer had failed to produce evidence of the adverse impact on the school of the claimant's long term absence; and also there was a less discriminatory means of achieving the legitimate purpose – to "wait a little longer" to establish whether she would be able to return to work in the near future.

The EAT allowed the appeal – the employer did not need to prove the adverse effect; it was obvious that the long term absence of a senior employee with the claimant's roles would have had an adverse impact on its business.

Now the Court of Appeal has reinstated the Tribunal's decision. The employer's decision to dismiss had to be examined as at the date of the internal appeal. The claimant's case that her dismissal could not be justified was very weak at the time of the original decision to dismiss – she had been off work for over a year and there was no evidence that she would be fit to return in the foreseeable future. But the position changed at the appeal stage. Although the evidence she produced at that hearing – her GP's Fitness for Work note – was cursory, it did raise the question of whether it was unjustifiable for the appeal panel to confirm the dismissal in the light of that new evidence.

Lord Justice Underhill commented that the case was "near the borderline" because of the length of absence and the unsatisfactory nature of the evidence about when she might be fit to return, but the Court concluded (by a majority) that it was open to the Tribunal to find that it was disproportionate/unreasonable for the employer to disregard the evidence without at least a further assessment by its own occupational health advisers.