Part-time status need not be the sole cause of less favourable treatment

The Supreme Court has held that a worker’s part-time status need only be an effective cause of less favourable treatment under the Part-time Workers Regulations. It need not be the sole cause.Nationalarchives The unanimous judgment in Augustine v Data Cars Limited allows the worker’s appeal and rejects the narrower causation approach followed by the courts below.

Warren Augustine was a private-hire driver who worked an average of 34.8 hours a week. Data Cars charged all drivers a fixed £148 weekly circuit fee to access its booking system, regardless of hours workedNationalarchives. Augustine’s chosen full-time comparator worked more than 90 hours a week. The fixed charge therefore cost Augustine more per hour of driving and left him with a lower proportion of his earnings.

The employment tribunal had dismissed the claim, including on the basis that any disadvantage was not solely because Augustine worked part time. The Employment Appeal Tribunal and the Court of Appeal majority held that they were bound to follow McMenemy, a decision of the Inner House of the Court of Session. The Supreme Court concluded that the domestic regulations require an effective causal connection, even where other causes also contribute to the treatmentNationalarchives.

A claimant must still identify a comparable full-time workerNationalarchives and establish less favourable treatment on the ground of part-time statusNationalarchives. Normally both workers must be employed by the same employer under the same type of contract. They must do the same or broadly similar work, having regard where relevant to qualifications, skills and experience. The comparator must work at the same establishment unless no qualifying full-time comparator works thereNationalarchives. Regulation 3 provides a comparison with previous full-time terms when a worker continues under a new or varied contract with fewer weekly hoursLegislation. Regulation 4 covers a former full-time worker returning to the same employer in less than twelve months, to the same job or one at the same level, with fewer weekly hours.

The pro rata principle applies when assessing less favourable treatment unless it is inappropriateNationalarchives. The court accepted that the higher hourly fee involved less favourable treatment attributable to Augustine’s lower hours. The court said the chosen comparator’s hours above 43.17 per week might be considered when determining what compensation should be awarded on a just and equitable basis.

Objective justification remains a separate defenceNationalarchives. Arguments about the business’s need to generate revenue and possible software limitations were better considered as potential justifications for the treatment. Other causes may also affect compensation; their existence does not by itself prevent the right under regulation 5 from arisingNationalarchives. Nor does the fact that only some part-time workers suffer the disadvantage rule out a claim where part-time status is an effective causeNationalarchives.

The legal basis is the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000, particularly regulations 2–5Nationalarchives, as interpreted in Augustine v Data Cars Limited [2026] UKSC 30Nationalarchives.