Augustine v Data Cars Limited [2026] UKSC 30

Mr Augustine, a part-time private hire driver, was charged the same fixed weekly circuit fee as full-time drivers, meaning he paid more per hour worked. The Supreme Court held that part-time status need only be an effective cause, not the sole cause, of less favourable treatment under the 2000 Regulations.

Facts

The appellant, Warren Augustine, worked as an employed private hire driver for Data Cars Ltd in 2016, averaging 34.8 hours per week. The employment tribunal found this made him a part-time worker, whereas other drivers averaged over 43 hours per week and some worked more than 60. His chosen comparator worked over 90 hours per week. All drivers, regardless of hours worked, were required to pay a fixed weekly ‘circuit fee’ of £148 to access the respondent’s booking dispatch system. Because the fee was fixed, part-time drivers paid a higher fee per hour worked and took home a lower proportion of earnings than full-time comparators.

Mr Augustine claimed this constituted less favourable treatment contrary to regulation 5 of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000. The employment tribunal dismissed the claim, holding (i) there was no less favourable treatment, and (ii) alternatively, any such treatment was not on the ‘sole ground’ that he was part-time, but was a means of generating revenue. The EAT overturned the first finding but considered itself bound by the Inner House decision in McMenemy v Capita Business Services Ltd [2007] CSIH 25 to apply a sole cause test. The Court of Appeal majority (Bean and Edis LJJ) considered McMenemy wrong but felt bound by it; Elisabeth Laing LJ agreed with McMenemy. Permission to appeal was granted to resolve the issue UK-wide.

Issues

The central issue was whether the right in regulation 5(1) of the 2000 Regulations applies only where the claimant establishes that part-time status was the sole ground for the less favourable treatment, or whether it suffices that part-time status was an effective cause of it. This turned on the meaning of the words ‘on the ground that’ in regulation 5(2)(a), and whether those words must be read consistently with the phrase ‘solely because’ in clause 4.1 of the Framework Agreement annexed to the Part-time Work Directive 97/81/EC.

Arguments

Appellant

Mr Jones KC submitted that ‘on the ground that’ is a well-established causation test in discrimination law, extending to situations where the protected status is an effective cause but not the sole cause of the less favourable treatment. He relied on domestic authorities such as Nagarajan v London Regional Transport [2000] 1 AC 501 and O’Neill v Governors of St Thomas More School [1997] ICR 33, and pointed to CJEU decisions including MK v Lufthansa CityLine GmbH and ZT v Ministero dell’Istruzione where competing rationales were treated as matters going to objective justification rather than causation.

Respondent

Mr Mountford submitted that the 2000 Regulations must be read consistently with clause 4.1 of the Framework Agreement, which requires that less favourable treatment be ‘solely because’ the worker is part-time. He argued that the word ‘only’ in regulation 5(2), and the singular use of ‘ground’, supported a narrow causation test. He further submitted that the fixed circuit fee arose from the standard industry practice of generating revenue and from software limitations, not from part-time status.

Judgment

Lady Simler (with whom Lord Lloyd-Jones, Lord Hamblen, Lord Leggatt and Lord Richards agreed) allowed the appeal.

Approach to causation in discrimination law

The Court reviewed the well-established meaning of ‘on the ground of’ in discrimination law by the time the 2000 Regulations were made. Lord Nicholls in Nagarajan had recognised that discrimination may be on protected grounds even if not the sole ground, and that if the protected ground had a ‘significant influence’ on the outcome, discrimination is made out. Similar reasoning applied to whistleblowing detriment cases (Fecitt v NHS Manchester [2011] EWCA Civ 1190), rejecting a sole or principal reason test.

Meaning of ‘solely because’ in the Framework Agreement

The Court found it unclear why ‘solely’ was included in clause 4.1 of the Framework Agreement and what it was intended to achieve. The CJEU authorities relied on (notably Wippel) merely restated the language without engaging with its precise meaning or excluding cases with multiple causes. The Court also rejected assistance from ILO Convention 175 as too tenuous a link. Ultimately, the Court did not decide the meaning of ‘solely because’ in the Directive.

No conforming construction required

Applying Lord Mance’s approach in United States of America v Nolan [2015] UKSC 63, the Court held that where a Directive establishes minimum standards, a member state may legislate more generously, and no imperative arises to achieve a conforming interpretation. Section 19(1) of the Employment Relations Act 1999 was a broad enabling power, not confined to implementing the Directive. The Secretary of State deliberately adopted ‘on the ground that’—language with an authoritative pre-existing meaning in equality law—rather than ‘solely because’. There was no need to import the word ‘solely’ into regulation 5(2).

Meaning of regulation 5(2)(a)

The Court rejected the respondent’s textual arguments. The word ‘only’ in regulation 5(2) qualifies the requirement that both conditions (causation and lack of objective justification) be satisfied; it does not, as a matter of grammar, qualify the causal link so as to require sole causation. The singular use of ‘ground’ reflects the single protected characteristic of part-time status, not a requirement of exclusivity. Regulations 6 and 7 do not support a narrower reading. Consistency with the general approach to direct discrimination, and the protective purpose of the Regulations, both favoured an ‘effective cause’ test.

Application to the facts

The pro rata principle meant that the fixed circuit fee inherently disadvantaged part-time workers compared with a full-time worker working 43.17 hours per week. That difference was properly characterised as being on the ground of part-time status. Additional hours worked by the chosen comparator (over 90 hours per week) were relevant only to the just and equitable assessment of compensation. The respondent’s suggested alternative explanations (industry practice, software limitations) were better viewed as potential objective justifications, which the respondent had expressly declined to advance.

Implications

The decision provides an authoritative UK-wide statement that under regulation 5(2)(a) of the 2000 Regulations, less favourable treatment need only be effectively caused by part-time status; it need not be the sole cause. The Inner House’s contrary reasoning in McMenemy on causation is disapproved, though its result on the facts is not disturbed. The approach in Sharma v Manchester City Council [2008] ICR 623 is endorsed.

The judgment reaffirms that where domestic legislation implements an EU Directive that permits more generous protection, the courts should give effect to the domestic wording as enacted and not read down protections by importing narrower Directive language. This reflects the wider principle articulated in Nolan.

Practically, the decision matters to part-time workers and their employers. Part-time workers may now bring regulation 5 claims where part-time status is a material or effective cause of less favourable treatment, even where other reasons exist. Employers must therefore either treat part-time workers no less favourably on a pro rata basis or be prepared to justify differential treatment on objective grounds. Where multiple causes exist, they should be addressed at the justification or remedy stage, not to defeat the claim at the threshold. The Court left open the precise meaning of ‘solely because’ in clause 4.1 of the Framework Agreement, so the interpretation of the Directive itself remains unresolved. The judgment is confined to the causation question and does not alter the requirements of comparability, less favourable treatment, or the availability of objective justification.

Verdict: The Supreme Court unanimously allowed the appeal. It held that regulation 5 of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 prohibits less favourable treatment of part-time workers where their part-time status is an effective cause of the impugned treatment; it need not be the sole cause.

Source: Augustine v Data Cars Limited [2026] UKSC 30