Section 4A of the Disability Discrimination Act 1995 provides that where a provision, criterion or practice supplied by, or on behalf of an employer places a disabled person at a substantial disadvantage in comparison with persons who are not disabled, it is the duty of an employer to take such steps as is reasonable, in all the circumstances of the case, to prevent the provision, criterion or practice or feature having that effect.  Where an employer fails to comply with this duty it will be found to have discriminated against the employee in question.

As highlighted by the House of Lords (now the Supreme Court) in the decision Archibald v Fife Council [2004] UKHL32 [2004 IRLR651 [2004] ICR594, the