Augustine v Data Cars Ltd [2025] UKSC

In this case, the Supreme Court (“SC”) has clarified the causation test for less favourable treatment of part-time workers under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (the "Regulations").

The Claimant worked part-time as a private hire driver, averaging around 34 hours per week. The Respondent charged all drivers a fixed weekly fee of £148 to access its booking system, regardless of how many hours they worked. Full-time drivers worked significantly more hours, meaning the Claimant was effectively paying more per hour than his full-time colleagues and taking home less pay per hour worked.

The central question was how closely a worker's part-time status must be linked to the less favourable treatment for a part-time worker discrimination claim to succeed. The Respondent argued that part-time status had to be the only reason for the less favourable treatment. The Claimant argued it was enough that part-time status was one of the reasons, even if not the only one.

The Employment Tribunal and Employment Appeal Tribunal both dismissed the Claimant’s claim, holding that the fixed fee was charged to generate revenue and not solely because he worked part-time. The Court of Appeal agreed, reluctantly following the Scottish case of McMenemy v Capita Business Services Ltd [2007] CSIH 25; [2007] IRLR 400, which had established the "sole reason" approach (see our previous case update here).

The SC disagreed. It held that a worker does not need to show that part-time status was the only reason for the less favourable treatment. It is sufficient that part-time status was an effective cause, meaning one of the real reasons. This brings the Regulations into line with the causation test applied across other discrimination claims.

For employers (particularly those who engage part-time workers), this is a significant development. A worker’s part-time status need only be an effective cause, not the sole cause, of less favourable treatment to be potentially unlawful under the Regulations. This is a significantly easier threshold for a worker to meet. Business reasons for a policy will therefore no longer defeat a claim at the outset. They will instead need to be relied upon as objective justification for what is otherwise unlawful treatment. Any arrangements that do not account for hours worked, such as flat-rate fees or fixed charges, should be reviewed carefully and documented with clear justification.

Lightbulb © 2026

Privacy Policy