The Supreme Court has ruled in favor of a part-time worker in a significant discrimination case concerning the treatment of part-time employees relative to full-time counterparts. The judgment clarifies that employers may not treat part-time workers less favorably if their part-time status is an effective cause of the treatment, even if it is not the sole cause.

Warren Augustine, a private hire driver employed by Data Cars Ltd, brought the case after challenging a fixed weekly fee charged to all drivers regardless of hours worked. Augustine argued that the fee structure resulted in higher charges per hour for part-time drivers like himself compared to full-time drivers, constituting less favorable treatment under regulation 5 of the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000.

Lower courts had dismissed Augustine’s claim. The employment tribunal found that the fee was necessary for the business’s revenue and not levied solely because the claimant was a part-time worker. The Employment Appeal Tribunal and the Court of Appeal, while sympathetic to Augustine’s interpretation of the law, felt bound to follow an earlier decision by Scotland’s Court of Session, which required part-time status to be the sole reason for any less favorable treatment.

The Supreme Court, led by Lady Simler, rejected this restrictive interpretation. It held that the regulations, implemented under section 19 of the Employment Relations Act 1999 to incorporate Council Directive 97/81/EC (the Part-time Work Directive), prohibit less favorable treatment if part-time status is an effective cause—even if not the sole cause. The court reasoned that the phrase “on the ground that” in anti-discrimination law already encompasses treatment where the protected characteristic has a significant or substantial influence.

The ruling addressed tensions between the regulations and the Framework Agreement on part-time work, which prohibits less favorable treatment “solely because” of part-time status. The Supreme Court found that although the Framework Agreement uses the word “solely,” the UK’s regulations do not adopt that narrower test. The broad enabling power granted to the Secretary of State under the Employment Relations Act allowed for more extensive protection than the Directive’s minimum requirements.

The Court emphasized that requiring sole causation would depart from established anti-discrimination jurisprudence and could lead to unjust and uncertain outcomes. While the presence of other reasons for differential treatment remains relevant for assessing justification or remedies, it does not negate the right not to be treated less favorably where part-time status is an effective cause.

This judgment marks a significant clarification in discrimination law, underscoring the protections afforded to part-time workers and potentially affecting employment practices across the UK.