If an employee is disabled, an employer has a duty to make reasonable adjustments for them, under the provisions of the Equality Act 2010. That duty only arises if the employer either knows, or could reasonably be expected to know (para 20 Schedule 8 EqA) that the individual has a disability, and is "likely to be placed at a disadvantage" in comparison to someone who does not have a disability.

In Donalien v Liberata UK Limited 2018 EWCA Civ 219, the Court of Appeal referred to "constructive knowledge" as shorthand for this knowledge that an employer could reasonably be expected to have had. 

Edith Donalien ("the Employee") was a specialist in housing benefit and council tax, and her employer Liberata UK Limited ("the Employer") provided her services to the London Borough of Southwark to deal with court hearings in these areas on its behalf. When she became ill, the Employee obtained a series of fit notes from her GP. These gave the reasons for her absence as being variously high blood pressure, stomach problems and wrist pain, and then finally work-related stress.

The Employer referred her to an Occupational Health consultant, who advised that in his view, the Employee was not disabled, and that her problems were "managerial, not medical". This tied in with the Employer's experience of dealing with the Employee, but it did not rely solely on the report when it decided to dismiss her. It held other meetings of its own with the Employee and also took correspondence from her GP into account. The Employee had refused to allow Occupational Health to contact her GP, but significantly, the Employer then went back to the Occupational Health consultant to clarify aspects of the report, and ask questions. 

In Gallop v Newport City Council [2013] EWCA Civ 183, the Court of Appeal had said that employers must come to their own conclusions about whether an employee is disabled or not, and should not blindly adopt an OH report. In this case, the Court was satisfied that this was not a "rubber stamp" exercise. It found that the Employer had done all it could reasonably be expected to have done to find out about the nature of the health problems that the Claimant was experiencing, and could not reasonably be expected to have known about her disability

This is a heartening judgment for employers dealing with difficult absence cases. The Court acknowledged here that the Employer had done enough to avoid being given constructive knowledge of the Employee's disability. It had been presented with "a good deal of not very clear information, and getting a good understanding of it was not helped by the (Employee's) rather uncooperative and confrontational stance" but had persisted, and made sufficient enquiry to discharge its duty. An employer facing similar circumstances should take care to take all of the information available to it into account when making decisions about employees, following up issues and raising appropriate questions where necessary, rather than taking information at face value.