The UK Supreme Court has made it significantly harder for employers to defend policies that happen to fall harder on part-time staff, even when part-time status was not the only reason for the treatment. In a unanimous ruling handed down on 12 August 2026 in Augustine v Data Cars Limited, five justices led by Lady Simler held that a worker only needs to show their part-time status was an “effective cause” of less favorable treatment, not the sole cause, to be protected under the Part-Time Workers Regulations.
The case began in 2016, when taxi driver Warren Augustine argued that a flat weekly circuit fee charged to all of Data Cars’ drivers, regardless of hours worked, breached part-time worker protections because it left part-time drivers paying more per hour than full-time colleagues. An employment tribunal, the Employment Appeal Tribunal, and the Court of Appeal all rejected or narrowed his claim before the Supreme Court took it up and ruled in his favor.
For HR and legal teams, the shift is procedural but consequential: employers can no longer defeat a part-time discrimination claim simply by pointing to a legitimate business reason that sits alongside a part-time-linked effect. If part-time status contributed to the treatment at all, that is enough to trigger liability, which raises the bar for how pay structures, fee schedules, and scheduling policies get reviewed before rollout, not just after a complaint lands.
The ruling lands as the UK is separately reworking rights for zero-hours and low-hours workers, and the combined effect is a tightening standard for how flat, uniform-looking policies get scrutinized for their disparate impact on part-time and casual staff, a pattern also visible in how US regulators are recalibrating their own compliance enforcement priorities this year.
Source: UK Supreme Court
