Supreme Court clarifies protection for part-time workers

The Supreme Court has handed down an important judgment on the scope of protection available to part-time workers under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (the Regulations). In Augustine v Data Cars Limited [2026] UKSC 30, the Court confirmed that a worker does not need to show that their part-time status was the sole reason for less favourable treatment. It is sufficient that part-time status was an effective cause of that treatment.

Facts of the case 

Mr Augustine worked as a private hire driver for Data Cars Limited. He was employed on a part-time basis, working an average of around 35 hours per week. Like all other drivers, regardless of the number of hours worked, he was required to pay a fixed weekly ‘circuit fee’ of £148 to access the company’s booking system.

Because the fee was charged at a flat rate, part-time drivers effectively paid more per hour worked than drivers who worked substantially longer hours. Mr Augustine argued that this amounted to less favourable treatment compared with a comparable full-time worker and brought a claim under the Regulations.

The employer’s defence was that the fee was not imposed because Mr Augustine was a part-time worker. Rather, it was a standard business model used to generate revenue and applied equally to all drivers. The employment tribunal dismissed the claim, holding, among other things, that part-time status was not the sole reason for the treatment. Mr Augustine’s appeals to the EAT and the Cout of Appeal were both unsuccessful (see our previous summary of the Court of Appeal’s decision).

Supreme court decision

The key question for the Supreme Court was whether the Regulations require a claimant to show that their part-time status was the sole reason for the treatment complained of, or whether it is enough that part-time status was one effective cause among potentially several reasons.

The Supreme Court unanimously allowed Mr Augustine’s appeal. It held that the Regulations do not require part-time status to be the sole cause of the less favourable treatment. Instead, part-time status need only be an effective or substantial cause of the treatment in question.

The Court identified several reasons for rejecting a sole-cause test.

1. First, the wording of the Regulations differs from the wording used in the EU Framework Agreement. The domestic legislation does not contain the words “solely because”. Parliament chose instead to use the familiar discrimination law phrase “on the ground that”, which already had an established meaning in UK law when the Regulations were enacted.
2. Secondly, the Court held that there was no need to interpret the Regulations so that they matched the minimum protection required by the EU Framework Agreement. The UK opted to provide more favourable protection for part-time workers than the Directive required.
3. Thirdly, the Court considered that a sole-cause test would produce artificial and potentially unfair results. Employers often make decisions for multiple reasons. Excluding claims whenever an employer could point to an additional factor behind the treatment would risk undermining the purpose of the Regulations and leave many instances of genuine part-time worker disadvantage without a remedy.

The Court also observed that where an employer has legitimate business reasons for a rule or practice, those considerations can be addressed through the Regulations’ objective justification defence, rather than by denying that part-time status played a causal role in the treatment.

The Birketts view

This is a significant and welcome clarification of the law. Employers will no longer be able to defeat a part-time worker claim simply by identifying another reason for the treatment alongside the worker’s part-time status. The focus will now be on whether part-time status was an effective cause of the disadvantage complained of.

The decision is likely to make it easier for part-time workers to pursue successful claims, so employers should consider whether any current policies, charges, benefits arrangements and reward schemes have a disproportionate impact on those working reduced hours. Employers should review such arrangements to ensure they comply with the pro rata principle and, where differences in treatment exist, consider whether they can be objectively justified.