Supreme Court Judgment Summary
Factual and Procedural Background
The Appellant was employed by Company A as a private-hire driver in 2016 and worked fewer weekly hours than typical full-time drivers. Company A charged every driver a fixed weekly fee for access to its booking system, regardless of hours worked. [1]
The Appellant worked an average of 34.8 hours per week, while drivers generally averaged more than 43 hours and his chosen comparator worked more than 90 hours. The employment tribunal therefore treated the Appellant as a part-time worker. [2]
The fixed fee of £148 per week caused the Appellant to pay more per working hour and retain less hourly pay than a comparable full-time driver. The employment tribunal nevertheless initially found no less favourable treatment because all drivers paid the same fee. [3]
Alternatively, the tribunal held that any disadvantage was not imposed solely because the Appellant worked part time, but arose from Company A's revenue model and possible software limitations. Applying McMenemy v Capita Business Services Ltd, it dismissed the claim. [4]
The Employment Appeal Tribunal overturned the finding that there was no less favourable treatment but dismissed the appeal because it considered itself bound by McMenemy's sole-ground test. [5]
A majority of the Court of Appeal considered the sole-ground test legally incorrect but likewise regarded McMenemy as binding and dismissed the appeal. A dissenting judge considered that regulation 5 required part-time status to be the sole ground for the treatment. Permission to appeal was granted so that the causation issue could be resolved throughout the United Kingdom. [6][7][8]
Legal Issues Presented
- Whether regulation 5(2)(a) of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 requires part-time status to be the sole cause of less favourable treatment, or merely an effective cause. [9]
- Whether regulation 5 must be construed consistently with the words “solely because” in clause 4.1 of the Framework Agreement on part-time work. [10][11]
- Whether the Appellant's part-time status was an effective cause of the disadvantage produced by Company A's fixed-fee system. [12][13]
Arguments of the Parties
Appellant's Arguments
- The phrase “on the ground that” carries the established discrimination-law causation test, under which a protected status need only be an effective cause rather than the sole cause of the treatment. [14]
- The Framework Agreement established minimum protections, while domestic legislation could provide broader protection. [15][11]
- The CJEU's decisions support a non-restrictive approach and show that explanatory reasons for differential treatment are ordinarily assessed as possible objective justification. [16][17]
- The omission of “solely because” and adoption of established domestic discrimination terminology indicated that regulation 5 was intended to employ the effective-cause test. [18]
Respondent's Arguments
- Regulation 5 should be interpreted consistently with clause 4.1 of the Framework Agreement, which protects workers treated less favourably “solely because” they work part time. [10][19]
- The word “only” and the singular “ground” in regulation 5(2) indicate that part-time status must be the exclusive reason for the treatment. [20][21][22]
- Charging a fixed fee was a standard method of generating revenue in the industry, and Company A's software may not have permitted another arrangement. [23]
- CJEU judgments repeatedly expressed clause 4.1 in sole-ground terms. [24]
Table of Precedents Cited
| Precedent |
Rule or Principle Cited For |
Application by the Court |
| McMenemy v Capita Business Services Ltd [2007] CSIH 25; [2007] IRLR 400 |
Applied a sole-ground test under regulation 5. |
The Court rejected its causation reasoning, although it considered the result correct on that case's facts. [25][26][27][28] |
| R (Jwanczuk) v Secretary of State for Work and Pensions [2023] EWCA Civ 1156; [2024] KB 275 |
Treated a decision of a coordinate court elsewhere in the United Kingdom as effectively binding. |
The approach had subsequently been disapproved by the Supreme Court. [6] |
| Sharma v Manchester City Council [2008] ICR 623 |
Part-time status need only be one reason for less favourable treatment. |
The Court endorsed its concern that a sole-cause requirement would undermine statutory protection. [7][29][30][31][32][33][34] |
| R (E) v Governing Body of JFS [2009] UKSC 15; [2010] 2 AC 728 |
Treatment is discriminatory where a protected characteristic influenced it or was inherently tied to its basis. |
Used to explain the ordinary approach to direct discrimination. [35] |
| R v Birmingham City Council Ex p Equal Opportunities Commission (No 1) [1989] AC 1155 |
Motive, intention and purpose are irrelevant where a criterion is inherently discriminatory. |
Supported the objective analysis of the reason for treatment. [35] |
| James v Eastleigh Borough Council [1990] 2 AC 751 |
Subjective motivation is irrelevant to inherently discriminatory treatment. |
Supported the Court's general causation analysis. [35] |
| Nagarajan v London Regional Transport [2000] 1 AC 501 |
A protected ground need only have a significant influence on the outcome. |
Demonstrated that discrimination may exist even where the protected ground is not the sole reason. [36][37] |
| O'Neill v Governors of St Thomas More Roman Catholic Voluntary Aided Upper School [1997] ICR 33 |
The protected factor need only be an effective cause, not the sole or main cause. |
Confirmed the established objective causation test. [38][39] |
| Aspinall v MSI Mech Forge Ltd EAT/891/01 |
Considered causation under statutory whistleblowing protection. |
The Court found that it did not clearly require exclusivity and noted that any such reasoning was later rejected. [40][41] |
| Fecitt v NHS Manchester [2011] EWCA Civ 1190; [2012] ICR 372 |
Liability arises where a protected disclosure is a material factor in detrimental treatment. |
Supported the proposition that “on the ground that” does not require a sole cause. [41] |
| Wippel v Peek & Cloppenburg GmbH & Co KG (Case C-313/02) [2005] 1 CMLR 9 |
Restated clause 4.1 and addressed comparability between part-time and full-time workers. |
The Court found that it did not decide whether multiple causes defeat a claim. [24][42][43] |
| MK v Lufthansa CityLine GmbH (Case C-660/20) [2024] IRLR 74 |
Clause 4.1 expresses the general principle of equality and must not be interpreted restrictively. |
The employer's explanatory reasons were considered as possible objective justification rather than independent causes defeating the claim. [16][44][17] |
| Zone de secours Hainaut-Centre, C-377/21, EU:C:2022:530 |
EU social-law protections should not be interpreted restrictively. |
Cited through the CJEU's reasoning in MK. [16] |
| ZT v Ministero dell'Istruzione e del Merito (Case C-268/24) ECLI:EU:C:2025:526 (“Lalfi”) |
Protection is not excluded merely because only some fixed-term workers suffer the disadvantage. |
The Court found the case supportive but not determinative of the multiple-cause issue. [45][46][47][48][49] |
| Gibson v Scottish Ambulance Service EATS/0052/04 |
Adopted a sole-ground causation test. |
Discussed as the approach followed in McMenemy and rejected in Sharma. [50][51][29] |
| United States of America v Nolan [2015] UKSC 63; [2016] AC 463 |
No conforming interpretation is imperative where a Directive permits broader domestic protection. |
Supported reading the 2000 Regulations according to their own language. [52][53][54][28] |
| Marleasing SA v La Comercial Internacional de Alimentacion SA (Case C-106/89) [1990] ECR I-4135 |
Domestic implementing legislation should ordinarily be construed consistently with an EU Directive. |
Cited within Nolan's explanation of the limits of conforming construction. [53] |
| Vodafone 2 v Revenue and Customs Comrs [2010] Ch 77 |
Recognized the principle of conforming construction. |
Cited within Nolan. [53] |
| Swift (trading as A Swift Move) v Robertson [2014] 1 WLR 3438 |
Recognized the principle of conforming construction. |
Cited within Nolan. [53] |
| R (Risk Management Partners Ltd) v Brent London Borough Council [2011] 2 AC 34 |
Domestic regulations may be construed as back-to-back with a Directive where that was intended. |
Used as an example contrasting with the broader domestic scheme in this appeal. [54] |
| Teckal Srl v Comune di Viano (Case C-107/98) [1999] ECR I-8121 |
Supplied the EU limitation reflected in domestic implementing legislation. |
Cited within Nolan's discussion of back-to-back implementation. [54] |
| Matthews v Kent and Medway Towns Fire Authority [2006] UKHL 8; [2006] 2 All ER 171 |
Addressed the relationship between domestic protection and EU minimum requirements. |
Cited in support of the limits of conforming construction. [55] |
| R (O) v Secretary of State for the Home Department [2022] UKSC 3; [2023] AC 255 |
Statutory language must be interpreted in context and according to purpose. |
Supported focusing on the actual words and purpose of regulation 5(2)(a). [56] |
| R (PACCAR Inc) v Competition Appeal Tribunal [2023] UKSC 28; [2023] 1 WLR 2594 |
Confirmed the contextual and purposive approach to statutory interpretation. |
Applied when construing regulation 5(2)(a). [56] |
Court's Reasoning and Analysis
The statutory scheme requires a claimant to identify a comparable full-time worker, establish less favourable treatment, and show that the treatment was on the ground of part-time status. The employer may then establish objective justification. [57]
Applying the pro rata principle, the fixed fee necessarily caused the Appellant to retain a lower proportion of his earnings than a comparable full-time driver. His lower working hours were therefore at least an effective cause of the disadvantage. [12][13]
By 2000, “on the ground of” had an established meaning in discrimination law: the protected ground needed to exercise a significant or substantial influence or be an effective cause, but did not need to be the main or sole cause. [58][59]
The CJEU authorities did not resolve whether “solely because” in clause 4.1 excludes claims involving multiple causes. Those decisions generally repeated the phrase without analysing its effect. [60][61][62][63][64]
The Court did not need to determine the precise meaning of “solely because” in the Framework Agreement because the Agreement established minimum rights and permitted member states to introduce more favourable provisions. [15][65][11]
Section 19 of the Employment Relations Act 1999 granted a broad, free-standing power to protect part-time workers and was not confined to minimum implementation of the Directive. [66][67]
The Secretary of State deliberately used terminology drawn from established domestic equality legislation rather than reproducing “solely because.” This indicated that the established effective-cause jurisprudence governed regulation 5. [18]
The word “only” in regulation 5(2) requires both a causal connection and the absence of objective justification; grammatically, it does not make part-time status the sole cause. [21]
The singular word “ground” identifies the single protected status—part-time work—and does not exclude the existence of additional reasons for the treatment. [22][68]
A sole-cause test would produce unreasonable outcomes and exclude many cases in which part-time status effectively causes the disadvantage alongside another factor. That result would conflict with the protective purpose of the Regulations, particularly because employers retain an objective-justification defence. [34]
Other causes may be relevant to objective justification or compensation, but they do not prevent the statutory right from arising where part-time status is an effective cause. [69]
Holding and Implications
APPEAL ALLOWED. Regulation 5 prohibits less favourable treatment where part-time status is an effective cause of the treatment; it need not be the sole cause. [70]
The ruling resolves the causation issue throughout the United Kingdom and rejects the sole-ground interpretation previously derived from McMenemy. The Appellant established the required causal connection because the fixed fee inherently disadvantaged him by reference to his lower working hours. [6][12][13][70]
Additional causes remain potentially relevant to objective justification and to any compensation assessed on a just and equitable basis. [13][69]