If an employee makes a request for flexible working under the statutory scheme, the employer can only refuse the request for one or more of eight specific reasons. The employee can make a complaint to a tribunal if there have been "procedural failings" – including where the employer "bases its decision on incorrect facts". The key point is that a tribunal cannot substitute its own decision as to whether the request should have been granted or question the business reasons behind the employer's decision. The decision in Singh v Pennine Care NHS Foundation Trust illustrates this distinction.

For several years the claimant had been working night shifts at a residential home for patients with mental health problems – until a childcare crisis meant that she needed to switch to daytime working. Her request was refused for three of the statutory reasons – additional costs (bringing in agency staff); detrimental effect on the employer's ability to provide a service; and inability to reorganise work amongst existing staff. These were all linked to the need to maintain the required safe staffing levels.

The claimant argued that the decision was based on incorrect facts – she claimed that her night shift could be accommodated by existing staff and produced rotas which she said supported her case. But the Tribunal rejected her claim, as did the EAT.

The Tribunal had based its decision on evidence given by the employer, including the detailed rejection letter to the claimant and an internal briefing paper on flexible working contracts. The Tribunal accepted the existence of the difficulties around levels of staffing and budget for staff, the need for sufficient cover at night and minimum staffing levels. Although the Tribunal had not got into the detail of why the claimant's counter-argument was not viable, it was clear that it had accepted the employer's proposition that it was unable to devise a system with existing staff that would provide the required cover. There was no scope for re-visiting the employer's decision – tribunals can examine and decide on the factual correctness of an asserted ground for refusing a request, but not its fairness and reasonableness.

The position might have been different had the claimant brought an indirect sex discrimination claim. The tribunal would then have had to investigate whether the refusal to move the claimant to day shifts was objectively justified – assuming that the claimant was able to show that a requirement to work night shifts put women at a particular disadvantage.