Employment Law Cases

Part-time workers, less favourable treatment and justification

British Airways v Pinaud

The requirement for a part-time worker to be available for work on proportionately more days than a full-time worker was less favourable treatment. In deciding whether such treatment is legally justified, tribunals should consider statistical evidence.

Under the Part Time Workers Regulations 2000, part-time workers have the right not be treated less favourably than comparable full-time workers in the terms of their contract. To decide whether a part-time worker has been treated less favourably, the pro rata principle is normally applied. If less favourable treatment is found, an employer will have a defence if it can show that the treatment is objectively justified. Less favourable treatment of a part-time worker can be justified on objective grounds if it can be shown to be necessary and appropriate to achieve a legitimate business objective.


Mrs Pinaud worked for BA, initially full time but then on a part-time basis after her maternity leave. BA’s contractual shift patterns meant that full-time employees had to be available to work for 243 days per year. Although 50% of this figure is 121.5 days, the pattern applicable to part-time workers working for 50% of ‘full time’ pay meant they had to be available for 130 days per year Proportionately, this required more days’ availability for the same level of (pro-rated) pay. Whether an employee was full time of part time they were required to ‘bid’ for hours during the days in which they were deemed to be available to work. Effectively, this meant that Mrs Pinaud’s working hours regularly varied as she could choose to work more days and whether she worked on a long-haul or short-haul flight. Despite Mrs Pinaud’s working hours varying her pay remained the same. Mrs Pinaud argued that, during her years as a part-time worker, she had been treated less favourably on the grounds of her part-time worker status because she had to be available for 53.5% of full-time hours, but was paid only 50% of a full-time salary.

Tribunal and EAT decisions

The tribunal held that Mrs Pinaud had been treated less favourably on the grounds she was a part-time worker. BA argued that any less favourable treatment was justified on objective grounds. Its argument was that Mrs Pinaud’s hours of work were broadly the same as her comparator’s hours and any variation was minimal so as to amount to a proportionate means of achieving a legitimate aim – that being to provide a workable contract of 50% hours despite the working year not being divisible precisely by the full-time or part-time hours. The tribunal agreed that BA had a legitimate aim but held that the less favourable treatment was not objectively justified and that a non-discriminatory way of achieving the same aim would be to pay workers on the part-time shift pattern an annual salary which was 53.5% of the full-time salary. The tribunal also said that BA’s statistical evidence (which BA said showed that the hours Mrs Pinaud actually worked were not that different from a full-time comparator) was irrelevant. BA appealed, arguing that the tribunal shouldn’t have ignored the statistical evidence when considering whether the discriminatory treatment was justified.

The EAT, while dismissing BA’s appeal on the main point (whether there had been less favourable treatment), did allow BA’s appeal on the justification issue. While it was sceptical of BA’s argument, the EAT thought that its case had to be addressed by looking at the statistics. A tribunal had to make a practical assessment of the impact of the unfavourable treatment, when deciding whether the treatment was objectively justified. It was part of BA’s case that the impact of the less favourable treatment was minimal, because the statistics showed that the part-time worker was, in practical terms, not actually required to work more hours than her full-time comparator. The case was sent back to a new tribunal to consider the justification issue afresh.

BA appealed the finding of less favourable treatment to the Court of Appeal.

Court of Appeal decision

The Court of Appeal gave pretty short shrift to BA’s appeal and rejected it, holding that a requirement to be available for 53.5% of the number of days in return for 50% of the pay was prima facie less favourable treatment of a part-time worker. Ms Pinaud's contract required her to be available for work on 130 days a year. By contrast, the full-time comparator’s contract required her to be available on 243 days a year. Ms Pinaud received 50% of the comparator’s salary. As half of 243 is 121.5, the tribunal had been right to hold that there had been prima facie less favourable treatment.

The case has now been remitted to the tribunal to consider the justification defence and, if that is rejected, remedy. The Court of Appeal commented that the tribunal should pay careful attention to what the EAT had to say about how the justification issue should be approached. Over 600 of Ms Pinaud’s colleagues have presented similar claims, which have been stayed pending the outcome of this case.

Link to judgment: https://www.bailii.org/ew/cases/EWCA/Civ/2018/2427.html


Cases on appeal under the Part Time Workers Regulations 2000 are relatively rare, probably because employers are pretty familiar with the pro rata principle. This decision does however illustrate how problems can arise where full- and part-time staff work complicated shift patterns. Some HR take outs from this case are:

  • Look carefully at whether your part-time staff are in reality working more hours for less pay than their full-time comparators, especially if you pay part timers a set basic pay when they work variable hours.
  • Statistically, more women than men work part time, so you could also face a claim for indirect sex discrimination by discriminating against part-timers. Ensure that even if you can justify different treatment between part timers and full timers on objective grounds, that those grounds are unrelated to the sex of the employee and there is no disproportionate impact on women.
  • Where any less favourable treatment is unavoidable due to a legitimate business interest, record the business aim pursued and, where possible, use statistics to evidence how the relevant measures facilitate this in a proportionate way. Simply increasing a part-timer’s salary will not necessarily solve the problem; the EAT emphasised the need to evaluate the impact of unfavourable treatment on individual employees when determining the question of proportionality.