The case of Augustine v Data Cars Limited has been journeying its way through the court system since 2022 and finally reached its conclusion, in the Supreme Court, earlier this year. The case provides helpful clarification (and the final say) on the issue of part-time worker discrimination and, specifically, the causation test which applies to such claims.
The Law
The Part Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (the “PTW Regulations”) contains the relevant law. Under Regulation 5(2) part-time workers have the right not to be treated less favourably than comparable full-time workers where:
- the treatment is on the ground that the worker is a part-time worker, and
- the treatment is not justified on objective grounds.
Domestic case law has historically been conflicted on the correct causation test, with the Scottish courts applying a sole causation test (in the case of McMenemy, an Inner House of the Court of Session case), in contrast to the broader effective cause test established in general discrimination law and followed by the courts in England and Wales. The Inner House of the Court of Session is the Scottish equivalent of the Court of Appeal in England and Wales and therefore sits above the Employment Appeal Tribunal. Until recently, it was the most authoritative case on part-time worker discrimination.
The Facts
Mr Augustine worked as a part-time driver for Data Cars Ltd. Data Cars charged all drivers, regardless of how many hours they worked, a flat rate “circuit fee” of £148 per week to access its booking system. Mr Augustine alleged that this resulted in part-time drivers, such as himself, being treated less favourably as they effectively had to pay a higher fee per hour to drive than a comparable full-time worker.
The Initial Decision(s)
At first instance, the Employment Tribunal dismissed Mr Augustine’s claim. Although it found that there was less favourable treatment, it held that this was not “solely” on the ground of Mr Augustine’s part-time status. It found that the circuit fee was charged because it was standard practice in the industry, rather than solely because Mr Augustine worked fewer hours. Mr Augustine appealed.
Although the EAT found that the Tribunal had erred by requiring part-time status to be sole reason for the treatment, it felt compelled to follow the narrower interpretation established in McMenemy. The Court of Appeal also upheld the decision, on the same basis, although the majority did find that McMenemy was wrongly decided. Mr Augustine appealed to the Supreme Court.
The Final Say
The Supreme Court therefore had to determine which causation approach to apply – the broader effective cause test or the narrower sole reason test. It unanimously found that the former should apply, meaning that the bar for claimants to establish less favourable treatment is now lower as part-time status only needs to be one of the causes of the treatment, rather than the only one. As the Supreme Court sits at the top of the court hierarchy, there is no more right of appeal meaning this is the final say on the matter.
Effect of Decision
This latest judgment effectively lowers the bar for claimants in establishing part-time worker discrimination. This approach is not novel, though, as it merely brings the law in line with the standard causation test applied in discrimination cases more generally.
In practice, the decision will likely limit the defences an employer is able to run in relation to such claims as employees will now only need to prove that part-time worker status was an effective, rather than the sole, cause of any less favourable treatment. This is likely to result in the focus shifting towards whether any less favourable treatment is justified on objective grounds instead.
In view of this judgment (and the changes due to come into force as a result of the Employment Rights Act 2025) employers would be wise to audit their policies and procedures now to ensure that arrangements which apply to part-time workers do not inadvertently discriminate. In particular, employers should check that arrangements relating to pay, bonus, holiday and benefits are fair and proportionate. If a pro-rata approach is not considered feasible, the reasons why should be carefully and clearly documented in case justification is required at a later date.