Part-time workers across the UK have received an important clarification of their workplace protections following a Supreme Court ruling over when less favourable treatment can be linked to working part-time.
The judgment could have consequences well beyond the private-hire industry in which the case originated, particularly for workers who believe that apparently identical workplace arrangements leave them disadvantaged because they work fewer hours.
At the centre of the case was private-hire driver Warren Augustine and a simple question: does being part-time have to be the only reason somebody receives less favourable treatment before legal protection applies?
The Supreme Court’s answer was no.
The Court ruled that part-time status can be an effective cause of the treatment. It does not have to be the sole cause.
That distinction potentially makes it easier for workers to establish that the protections contained within the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000 apply to their circumstances.
What happened in the case?
Warren Augustine worked part-time as a private-hire driver for Data Cars Limited.
Drivers paid a weekly “circuit fee” to access the company’s booking dispatch system.
The same fixed fee applied irrespective of whether somebody worked full-time or part-time.
Mr Augustine argued that this disadvantaged him because, as somebody working fewer hours, the fixed weekly charge represented a higher cost for every hour he worked compared with a full-time driver.
His claim initially failed before the Employment Tribunal, and subsequent appeals were unsuccessful.
The issue eventually reached the UK’s highest court.
The Supreme Court’s official case record explains that the central legal question was whether the Part-time Workers Regulations apply when someone’s part-time status is an effective cause, rather than the sole cause, of less favourable treatment.
The Supreme Court unanimously allowed Mr Augustine’s appeal.
Why the Supreme Court decision matters
Under Regulation 5 of the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000, a part-time worker has the right not to be treated less favourably than a comparable full-time worker because they work part-time, unless that treatment can be objectively justified.
The Supreme Court concluded that the protected characteristic does not need to be the main or only reason for the treatment.
The Supreme Court’s official summary of Augustine v Data Cars Ltd explains that if part-time status had a significant or substantial influence on the outcome, or was an effective cause of it, that can be sufficient.
This matters because workplace decisions rarely have only one factor behind them.
An employer may have commercial, administrative or operational reasons for a particular arrangement while that arrangement simultaneously places part-time workers at a disadvantage.
The judgment means the existence of another reason does not automatically prevent the Part-time Workers Regulations from applying.
What could this mean for ordinary part-time workers?
The implications potentially reach much further than private-hire drivers.
Millions of people work part-time across retail, healthcare, hospitality, administration, education, logistics and other parts of the UK economy.
A worker might encounter differences involving pay arrangements, access to benefits, workplace charges, training opportunities or other terms and conditions.
Not every difference will amount to unlawful less favourable treatment.
But workers should not assume that an arrangement must explicitly say “part-time workers receive less” before legal protection can become relevant.
Our existing guide to part-time work and part-time workers’ rights explains the wider protections applying to workers who work fewer hours.
Part-time workers should generally receive treatment consistent with comparable full-time workers, with appropriate pro-rata arrangements where relevant.
Equal does not always mean identical
The Augustine case also demonstrates an interesting workplace principle.
Treating everybody identically does not necessarily produce an equal outcome.
Data Cars charged drivers the same fixed weekly fee.
At first glance, that might appear completely equal.
But a worker completing substantially fewer hours could effectively pay more for every hour they worked.
Consider a simple illustration.
If two workers were each charged £100 for access to something required for work, but one worked 40 hours and another worked 20 hours, the cost would effectively represent £2.50 per working hour for the full-time worker and £5 per working hour for the part-time worker.
The charge is identical.
The practical effect is not.
That distinction is one of the reasons the Supreme Court judgment is important.
Part-time working is becoming increasingly important
Part-time employment is not a marginal feature of the modern workplace.
People work reduced hours for many reasons.
Some combine employment with childcare or other caring responsibilities. Others study, manage health considerations, approach retirement gradually or simply prefer a working pattern offering greater flexibility.
Part-time employment can also provide a route back into work.
That makes effective protection against less favourable treatment increasingly important as employers develop more varied working arrangements.
It also connects with wider changes taking place around flexible employment.
We recently reported how new flexible-working rules are set to strengthen rights for millions of UK workers, with further reforms expected during 2027.
Workers whose applications for different working arrangements are rejected can also use our guide explaining what to do when a flexible-working request is refused.
Together, these developments demonstrate how working patterns are becoming an increasingly important area of employment law.
Does this mean every disadvantage is unlawful?
No.
The judgment should not be interpreted as meaning that every difference experienced by a part-time worker automatically becomes unlawful.
There still needs to be less favourable treatment compared with an appropriate full-time worker, and the worker’s part-time status must be relevant to that treatment.
Employers can also potentially defend different treatment where it is objectively justified.
The significance of Augustine is therefore more precise.
Workers do not have to demonstrate that working part-time was the only reason behind what happened.
The Supreme Court’s judgment says an effective causal connection can be sufficient.
That is an important clarification.
What should workers look out for?
Part-time workers who believe they are being disadvantaged should look carefully at how comparable full-time colleagues are treated.
Questions worth considering include whether hourly pay is equivalent, whether benefits are appropriately available on a pro-rata basis, whether training and development opportunities are genuinely accessible and whether workplace policies unintentionally penalise people working fewer hours.
Workers should also examine the practical effect of apparently neutral arrangements.
A policy applying exactly the same rule to everybody may still affect somebody working 20 hours very differently from somebody working 40.
Keeping written records can also be useful where concerns arise.
Contracts, payslips, workplace policies, emails and information showing how comparable full-time workers are treated may help establish what is actually happening.
An important clarification for UK workers
The significance of the Supreme Court judgment lies in a relatively small change in legal language with potentially substantial practical consequences.
A part-time worker does not need to prove:
“This happened solely because I work part-time.”
Instead, the question can be whether working part-time was an effective cause of the less favourable treatment.
That more accurately reflects the complexity of real workplaces, where decisions can have several motivations and consequences.
The Workers Union welcomes greater clarity around workplace rights because workers need rules they can understand and apply to real situations.
Part-time employment provides flexibility for millions of working people and helps businesses access workers whose circumstances may prevent them from following traditional full-time schedules.
Those workers should not automatically be placed at a disadvantage simply because their working week is shorter.
The Supreme Court has now provided important clarification about where that protection begins.
For workers wondering whether they are being treated differently because they work reduced hours, the message is worth remembering: part-time does not mean lesser rights.
