Asda Stores Ltd v Brierley and others

The Supreme Court dismissed the employer's appeal and held that the claimants could rely on a cross-establishment comparison with distribution employees. The court applied the established statutory framework under the Equal Pay Act 1970 (section 1(6)) and the Equality Act 2010 (section 79(4)), and confirmed that the relevant enquiry for a cross-establishment comparison is whether "common terms" would apply — broadly, whether the comparator's core terms would remain the same if the comparator were hypothetically employed at the claimant's establishment (the "North hypothetical").

The court emphasised that the common-terms requirement is a threshold, limited-purpose test designed to weed out comparisons that are clearly rooted in geographic or historical differences, not to substitute for the substantive equal-value or genuine material factor enquiries. Applying that approach, the Tribunal's findings on the North hypothetical — that distribution employees would, on the relevant hypothesis, remain on substantially the same terms and so were valid comparators — were not shown to be perverse or legally wrong, and the Supreme Court dismissed the appeal.

Background and parties. The appellant, Asda Stores Ltd, is a large supermarket operator. The respondents are predominantly female retail employees who brought equal pay claims alleging they were paid less than male comparators employed in Asda's distribution depots.

Nature of the claim and relief sought. The claimants sought equal pay compensation for up to six years prior to the start of proceedings, relying on cross-establishment comparisons with distribution employees who are predominantly male.

Procedural posture. The question whether the retail claimants could use distribution employees as comparators was tried as a preliminary issue. The Employment Tribunal (Employment Judge Tom Ryan) found for the claimants on common terms and the North hypothetical. Asda appealed unsuccessfully to the Employment Appeal Tribunal (Kerr J) and to the Court of Appeal ([2019] EWCA Civ 44). The appeal to the Supreme Court concerned whether the common terms requirement was satisfied.

Issues framed by the court.

• What is the statutory meaning and purpose of the "common terms" requirement in cross-establishment comparisons under the Equal Pay Act 1970 and the Equality Act 2010 (section 79(4))?
• Whether, applying the "North hypothetical" (i.e. assuming the comparator would be employed at the claimant's establishment), the distribution employees' core terms would be the same or substantially the same as at their own depots, so as to permit a cross-establishment comparison.

Key legal reasoning. The court reviewed leading authorities (Leverton, British Coal, North) and summarised that the common-terms enquiry is a narrow threshold test: where no employees of the comparator class work at the claimant's establishment, the tribunal must ask whether the comparator would be employed on the same or substantially the same terms if hypothetically located at the claimant's establishment. The court rejected an approach that elevates the threshold into a detailed line-by-line comparison or a proxy for the equal-value inquiry. Applying that legal framework, the Supreme Court concluded that the Employment Tribunal's findings in favour of the claimants on the North hypothetical were properly open on the evidence and should stand.

Wider context. The court emphasised that the threshold is limited and that employers have full opportunity to raise substantive defences (including the genuine material factor defence) and to contest comparability and value at later stages. The judgment also offers guidance to tribunals to keep threshold enquiries proportionate and to avoid prolonged document-heavy line-by-line comparisons.

Appeal dismissed. The Supreme Court held that the common terms requirement is a limited threshold test and that, applying the North hypothetical, the Employment Tribunal correctly concluded that distribution employees would have been employed on the same or substantially the same core terms if hypothetically located at the retail establishment. The Tribunal's factual findings on that hypothetical were not legally flawed and the appeal therefore failed.

Employment Tribunal (preliminary issue decided for claimants by Employment Judge Tom Ryan); Employment Appeal Tribunal (appeal by Asda dismissed by Kerr J); Court of Appeal [2019] EWCA Civ 44 (Asda's further appeal dismissed); appeal to the Supreme Court [2021] UKSC 10 (this judgment).