Supreme court rules on part-time discrimination

Claims for discrimination based on part-time status do not have a stricter causation test than other discrimination claims, the Supreme Court has ruled. If working part time is an effective cause of less favourable treatment, that is enough for a claim to succeed.

In the long-running case of Augustine v Data Cars Limited, the Supreme Court had to resolve a conflict in the caselaw about part-time work discrimination. Previous rulings were divided on whether individuals needed to show that their part-time status was the sole cause of less favourable treatment (a high hurdle), or simply an effective cause (a much easier test). The Supreme Court adopted the easier, broader test, confirming that the causation threshold for part-time work discrimination is no higher than for other discrimination claims. The practical effect is to reduce the scope for employers to defeat claims on causation grounds, and to shift the focus firmly onto justification.

The question of causation

Under the Part Time Workers (Prevention of Less Favourable Treatment) Regulations 2000, part-time workers have the right not to be treated less favourably than comparable full-time colleagues where:

the reason for the treatment is that the worker is a part-time worker, and
the treatment is not justified on objective grounds.

The Supreme Court ruling concerned the first part of this test – causation.

The claim was brought by Mr Augustine, a private hire driver engaged by Data Cars. Mr Augustine worked fewer hours per week than typical full-time drivers. All drivers were charged a weekly “circuit fee” of £148 to access the employer’s booking system. Mr Augustine claimed that this was discriminatory on grounds of his part-time status because, in effect, he paid a higher fee per hour to drive than a comparable full-time driver. The employment tribunal considered that this treatment was not because Mr Augustine was a part-time worker, or at least his part-time status was not the sole cause. The case went to the Employment Appeal Tribunal and Court of Appeal before eventually reaching the Supreme Court.

The Supreme Court ruled that workers treated less favourably because they work part-time do not need to show that their part-time status was the sole cause of the less favourable treatment. It is enough that it is an effective cause. In other words, a part-time worker need only show that their part-time status was one of the operative causes of the less favourable treatment. This is the last word on the causation test, since there’s no further right of appeal.

Practical impact

The Supreme Court judgment brings the law on part-time worker discrimination in line with the standard approach to causation in discrimination cases. In practice, it closes the door on more technical arguments that any less favourable treatment was for mixed reasons, not just part-time status. It shifts the focus away from the detailed reasons for the treatment and towards whether it is justified on objective grounds.

The Supreme Court confirmed that the existence of other reasons for the treatment may be relevant to the justification question, or to the amount of compensation awarded. This means that, while the Supreme Court has broadened the scope for part-time employees to bring claims, employers can still rely on many of the same arguments for treating part-timers differently in appropriate cases,

For employers, it could be a good moment to take stock of your arrangements for part-time workers:

Pay: A simple ‘pro rata’ calculation should be made so that the part-time worker is paid the same per hour as a comparable full-time colleague. When it comes to decisions about pay increases and bonus awards, be careful to avoid less favourable treatment of part-time employees. Documenting your reasons is always important, especially where part-time and full-time workers are treated differently.
Benefits: The pro rata principle should be applied, unless it is inappropriate. For example, if a full-time worker gets 30 days’ holiday each year, someone working 50% of full-time hours should get 15 days. Where benefits cannot be pro-rated – as is often the case with health insurance, staff discounts and company cars – you will need to provide the whole benefit or face having to objectively justify not doing so. Many employers opt to make a proportionate contribution towards such benefits.
Flat fees and fixed charges: The Augustine case involved a flat fee applied to all workers, regardless of hours worked. Similar flat fee access arrangements should be reviewed and employers may want to consider a pro-rata approach where possible and appropriate. Where pro-rating is possible, employers would need to have clear and objective justification for not opting to do this. Our understanding is that Data Cars decided not to argue about justification at the original employment tribunal hearing and accepted that they would apply a reduced access fee if Mr Augustine won on the causation argument. The potential for justification will therefore need to be tested in further cases. Where the pro-rata approach isn’t possible – for example for fixed car leasing costs calculated per car or insurance costs calculated on headcount – justifying a fixed rate regardless of hours worked is clearly going to be easier.
Bank holidays: Some employers take a ‘normal working days’ approach, where a part-time employee can only take a paid bank holiday if it falls on one of their normal working days. The leading case on this approach (McMenemy) had unusual facts because the employer operated a seven-day week and applied the same ‘normal working days’ approach to both part-timers and full-timers. When a part-timer who worked Wednesdays, Thursdays and Fridays complained about missing the benefit of bank holiday Mondays, his claim failed because a full-timer who did not work Mondays would be in the same position. The Supreme Court in Augustine agreed with the outcome in McMenemy, but it still offers limited guidance on the more typical scenario where the comparable full-timer works Monday to Friday. The Augustine ruling limits the scope for employers to argue about the “causation” issue, so any challenge now would turn on justification. For employers, a safer approach is usually to give all part-timers a pro rata bank holiday allowance.
Other forms of less favourable treatment/detriment: Part-time worker detriment can crop up in a wide range of contexts so it is important to keep part-time status in mind when making or reviewing people decisions. For example, in one recent case part timers were expected to work a greater proportion of their working hours at the weekend than full-time comparators, and this was found to be less favourable treatment. Questions have also arisen about how ‘return to office’ mandates should apply to part-time employees – for example where full-timers are expected to come to the office 3 or 4 days per week. The main takeaway from Augustine is to focus on whether a part-time worker can argue that their part-time status has played a part in them experiencing less favourable treatment. If so, they are likely to be able to bring a claim and the crucial question will be whether this can be justified on objective grounds.