UK Supreme Court · [2026] UKSC 30

Augustine v Data Cars Limited

The Supreme Court allowed the appeal. It is enough if part-time status was an effective cause, unless the employer shows objective justification.

UK Supreme Court12 Aug 2026

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Quick read

An arrangement is not automatically fair because everyone receives the same rule or pays the same fixed amount.
The Supreme Court allowed the appeal.

Use this to check

Part-time status can be one effective cause among several
A uniform fixed fee can produce less favourable treatment when hours differ
The comparison normally requires an actual full-time worker doing the same or broadly similar work

Decision snapshot

What happened
- Warren Augustine was a private hire driver who worked for Data Cars as an employee in 2016.
- Every driver paid the same weekly circuit fee of GBP 148 to access its booking system, whatever hours they worked.
- Mr Augustine averaged 34.8 hours a week.
- The tribunal did not set a fixed definition of full-time hours, but found that drivers worked over 43 hours a week on average and his chosen comparator worked an average of over 90 hours.
What the court had to decide
- Did regulation 5 require Mr Augustine to show that part-time status was the sole ground for the treatment, or was it enough that part-time status was an effective cause?
- The answer mattered because Data Cars said the fixed fee also reflected how the business earned revenue.
What the court decided
- The Supreme Court unanimously allowed Mr Augustine's appeal on the causation issue.
- It held that, under regulation 5, part-time status need only be an effective cause of less favourable treatment.
- It does not have to be the sole cause.

Practical impact

Practical read

An arrangement is not automatically fair because everyone receives the same rule or pays the same fixed amount.
Compare a part-time worker with a suitable full-time worker, apply pro rata treatment unless it is inappropriate, then assess whether part-time status was an effective cause of any disadvantage and whether the difference can be...

Useful next steps

Part-time status can be one effective cause among several
A uniform fixed fee can produce less favourable treatment when hours differ
The comparison normally requires an actual full-time worker doing the same or broadly similar work
Commercial explanations or technical limits do not by themselves answer causation and may be relevant to objective justification
Pro rata treatment is the usual starting point unless it is inappropriate

A fixed weekly fee landed differently

Data Cars was a small private hire business. Its drivers used a booking dispatch system and each paid a circuit fee of GBP 148 a week.

The amount did not change with hours worked. Mr Augustine averaged 34.8 hours a week. The tribunal found that drivers worked more than 43 hours a week on average, with some working 60 or more, but it made no finding setting a fixed definition of full-time hours for the business. Mr Augustine's chosen comparator worked more than 90 hours a week. The same GBP 148 fee therefore represented a higher hourly cost for Mr Augustine.

Why the claim had failed in the courts below

The Employment Tribunal first said there was no less favourable treatment because every driver paid the same fee. In the alternative, it said the fee was charged because that was how Data Cars generated revenue, and it also referred to possible software limits, so part-time status was not the sole ground for any disadvantage. Data Cars made clear that, if there was prohibited less favourable treatment, it was not seeking to justify it on objective grounds.

The Employment Appeal Tribunal overturned the first point by applying the pro rata principle. It accepted that the fixed fee had a harsher effect on Mr Augustine because he worked part time.

The Employment Appeal Tribunal and the majority of the Court of Appeal also thought the better legal test was whether part-time status was an effective cause. Both nevertheless considered themselves bound by McMenemy v Capita Business Services Ltd, which they took to require part-time status to be the sole cause.

Question	Position before the Supreme Court ruling
Was Mr Augustine treated less favourably?	Yes. The higher hourly effect of the fixed fee was not challenged in the Supreme Court.
Was part-time status one cause?	The lower courts preferred the effective-cause test but felt bound by McMenemy. The Supreme Court confirmed that test and said the pro rata effect of the fee involved at least some less favourable treatment on the ground of part-time status.
Had Data Cars argued objective justification?	No. It made clear before the Employment Tribunal that it was not relying on that defence.

The Supreme Court confirmed an effective-cause test

The Supreme Court's answer was straightforward. Under regulation 5, part-time status can be one effective cause of the treatment. It does not have to be the only cause.

The Regulations use the words 'on the ground that' the worker is part time. The Court held that this language uses the established discrimination-law approach to causation.

Other explanations, including commercial or technical reasons, do not automatically defeat a claim at the causation stage. They may instead matter to objective justification.

What employers should examine

For employers, the legal sequence matters. First identify a suitable full-time comparator, usually an actual full-time worker employed by the same employer under the same type of contract and doing the same or broadly similar work. Then ask whether the part-time worker is treated less favourably, applying the pro rata principle unless that would be inappropriate.

If there is less favourable treatment, ask whether part-time status was an effective cause. Only after that should you consider whether the difference can be justified on objective grounds.

Key points

Identify the right full-time comparator under the same type of contract doing the same or broadly similar work
Compare fixed weekly charges, pay and benefits by hours as well as by cash amount
Apply the pro rata principle unless there is a sound reason why it is inappropriate
Keep separate notes on causation and on any objective justification
Check access to training, bonuses, promotion opportunities and workplace facilities
Be ready to answer a written request for reasons within 21 days
Do not retaliate against a worker for requesting reasons, alleging an infringement, giving evidence or bringing proceedings

Common questions

Did Data Cars charge part-time drivers a higher weekly fee?

No. Every driver paid the same GBP 148 weekly circuit fee. The problem was its effect: a driver working fewer hours paid a higher fee for each hour of access and kept a smaller proportion of earnings than the full-time comparator.

Does the ruling mean every fixed workplace charge is unlawful?

No. A claim still requires a suitable full-time comparator, less favourable treatment, a sufficient link to part-time status and no objective justification. The decision rejects only the idea that part-time status must be the sole cause.

Can an employer justify different treatment?

Potentially. Regulation 5 allows treatment that is justified on objective grounds. That is a legal test applied to the actual facts, not simply an employer saying that a policy is convenient or commercially useful.

Who can be protected by the Regulations?

The definition can cover employees and some other individuals who personally perform work under a contract, provided the other party is not their client or customer as part of the individual's own business undertaking. A regulation 5 claim will usually also require an actual comparable full-time worker under the same type of contract doing the same or broadly similar work.

Do I need an actual full-time comparator?

Usually, yes. In most cases the comparison must be with an actual full-time worker employed by the same employer under the same type of contract and doing the same or broadly similar work. Limited exceptions apply when a worker moves from full-time to part-time work or returns part time after an absence.

What if a worker asks for reasons or raises a claim?

A worker who considers that regulation 5 may have been breached can request written reasons, and the employer normally has 21 days to respond. The Regulations also prohibit specified retaliation for requesting reasons, alleging an infringement, bringing proceedings or giving evidence, subject to a limited exception for a false allegation not made in good faith.

How Sprintlaw can help

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Update history

Case12 Aug 2026

Supreme Court confirms effective-cause test for part-time worker treatment

In Augustine v Data Cars Limited, the Supreme Court held that part-time status need only be an effective cause of less favourable treatment. It does not have to be the sole cause.