CELESTINA MBA, a care worker who refused to work on Sundays (News, 2 March 2012), lost her appeal in the Court of Appeal last week in her claim that her employers' insistence that she should work on certain Sundays amounted to religious discrimination.

Mrs Mba is a Christian who attends a church in south London. She sincerely believes in the fourth commandment: that Sunday is a day for worship, and not for work.

In July 2007, she became employed as a care assistant in Brightwell, a children's home run by the London Borough of Merton. The children there have serious disabilities, and complex care needs arising from challenging behaviour; medical needs; feeding difficulties; and similar problems.

Her job description contained a clause that is not uncommon in an environment that necessitates 24-hour care, and requires her to "undertake duties outside normal working hours as required by the shift rota, including weekends, Bank Holidays, and sleeping duties".

Mrs Mba took the view that, as a result of what had passed between her and Merton Council's management at the time of her appointment, she was not contractually obliged to work on Sundays.

It was now accepted, however, that, while management would endeavour to arrange the rosters so as to permit Mrs Mba not to work on Sundays, and that was achieved in the early part of her employment, her legal obligation was to work on Sundays as and when required. When the council began to roster her for Sunday working, a dispute arose.

Mrs Mba raised a grievance, which was rejected, and she was scheduled to work certain weekends, including Sundays. She declined to do so, and disciplinary proceedings ensued, leading to a final warning. Her appeal against that was rejected (News, 4 January), and, at the end of May 2010, she resigned "with regret".

She then commenced proceedings in the Employment Tribunal, alleging constructive dismissal and indirect religious discrimination. The central issue now was religious discrimination.

The Employment Equality (Religion or Belief) Regulations 2003 provide by regulation 3(1) that "a person (A) discriminates against another person (B) if . . . A applies to B a provision, criterion, or practice which he applies or would apply equally to persons not of the same religion or belief as B, but which puts or would put persons of the same religion or belief as B at a particular disadvantage when compared with other persons . . . which puts B at that disadvantage, and which A cannot show to be a proportionate means of achieving a legitimate aim".

The Employment Tribunal ruled that the relevant "provision, criterion, or practice" was the requirement that staff work on Sunday shifts as rostered, and that the "legitimate aim" was the effective running of Brightwell in terms of service costs and staff.

On the question whether rostering Mrs Mba for Sunday working was "a proportionate means of achieving [that] legitimate aim", the tribunal took into consideration three factors.

First, that the council did make efforts to accommodate Mrs Mba's requirements for two years. Second, that the council was prepared to arrange the shifts in a way that enabled her to attend Sunday worship each Sunday; and, third, that her belief that Sunday should be a day of rest on which no paid employment was undertaken, although a deeply held belief by Mrs Mba, was "not a core component of the Christian faith".

On those grounds, the tribunal refused Mrs Mba's claim, and ruled that the council had acted in a proportionate manner. The Employment Appeal Tribunal upheld the Employment Tribunal's decision.

In the Court of Appeal, it was argued for Mrs Mba that the Employment Tribunal fell into legal error in relation to those three factors. Her complaint was that the first two were irrelevant to the question of proportionality, and that the third misstated the law. The Court of Appeal agreed that there was an error of law in the tribunal's reasoning.

Lord Justice Kay, Vice-President of the Civil Division of the Court of Appeal, who heard the case with Lord Justice Elias and Lord Justice Vos, said that it was not necessary to establish that all or most Christians, or all or most Non-conformist Christians, were, or would be put at a particular disadvantage. It was permissible to define a claimant's religion or belief more narrowly than that, and that was where the tribunal went wrong.

In describing Mrs Mba's Sabbatarian belief as "not a core component of the Christian faith", the tribunal "opened the door to a quantitative test on far too wide a basis". It was clear that for some Christians working on Sundays was unacceptable, and Mrs Mba's belief genuinely embraced that. On that basis, the tribunal should have found that Mrs Mba was disadvantaged, and that the real issue was whether that was "a proportionate means of achieving a legitimate aim".

Despite the legal error, however, all three judges found that, in the circumstances, the council had established that there was no viable and practicable alternative way of running Brightwell but to ask Mrs Mba to work on Sundays, in accordance with her contract. The requirements made of her to work on certain Sundays were a proportionate means of achieving an indisputably legitimate aim. The legal error made by the Employ- ment Tribunal made no differ- ence.

Nevertheless, the Christian Legal Centre, which supported Mrs Mba's claim, hailed the Court of Appeal's ruling that an individual believer's faith should be recognised, and, in principle, protected.

The director of the centre, Andrea Minichiello Williams, said that at last the courts were "beginning to demonstrate greater understanding of what it means to be a Christian". Many Christians, she said, would now be able to argue that their employer must respect their rights of sabbath worship.