Tesco Stores Limited v K Element & Ors

On an application for expert evidence in equal-value proceedings, the tribunal must apply the test in Employment Tribunals (Equal Value) Rules of Procedure 2013, Rule 10(1): whether the evidence is reasonably required to resolve the proceedings. It must not instead determine, at that procedural stage, that a pleaded issue is legally irrelevant unless that issue has been excluded.

The proper approach is to ask whether the evidence is necessary; if not, whether it would assist; and, if it would assist, whether it is reasonably required after balancing all relevant circumstances. Those circumstances include cost, delay, the value and effects of the claim, and the effect on the hearing. A tribunal must address the evidence sought for the pleaded issues in the relevant claim period.

More than 50,000 retail-store employees brought equal-value claims against Tesco. Tesco pleaded a material-factor defence, including labour-market conditions, recruitment and retention, competition, sustainability and the effects of pay equalisation.

The Employment Tribunal refused Tesco permission to adduce economic expert evidence on the relevant labour markets and on the consequences of paying store colleagues more. It treated the proposed consequences evidence as irrelevant because it understood Tesco to rely on the effects of a judgment requiring higher pay, including effects on prices and the public.

Tesco appealed the refusal. The central issue was whether the tribunal had applied the correct test for admitting expert evidence and understood the issues to which that evidence was directed.

1. Appeal allowed. The Employment Tribunal erred in law. It misunderstood the Consequences Issue as concerning the future consequences of a judgment against Tesco, rather than the claimed material factors during the period covered by the claims.

2. Rule 10(1) of the Employment Tribunals (Equal Value) Rules of Procedure 2013 required the tribunal to restrict expert evidence to that reasonably required to resolve the proceedings. The tribunal correctly stated that test, but did not apply it. Its predominant reasoning was instead that the Consequences Issue was irrelevant because the asserted effects on prices or the public could not establish a legitimate aim.

3. Whether a pleaded issue is relevant to the determination of the claim is distinct from whether expert evidence is reasonably required to determine that issue. In the absence of an application excluding the pleaded issue, the tribunal should have considered the expert-evidence application by reference to the disputed issues as pleaded.

4. Applying British Airways Plc v Spencer & Ors [2015] EWHC 2477 (Ch), the tribunal should first have asked whether the evidence was necessary. If it was not necessary, it should have considered whether it would assist in resolving the issues. If it would assist, it should have balanced all relevant factors to decide whether it was reasonably required. Its brief consideration of cost and delay did not amount to that assessment.

5. The refusal was set aside. The application was remitted to the same Employment Tribunal for a fresh determination. The errors were serious but the earlier decision was not wholly flawed, and the judge could be trusted to apply the correct approach without giving either party a second opportunity to reargue matters improperly.

• Employment Appeal Tribunal: Allowed Tesco’s appeal and set aside the refusal of permission for expert economic evidence: [2025] EAT 26.
• Employment Tribunal: Employment Judge Hyams, sitting alone, refused Tesco permission to adduce expert evidence after a hearing on 9 December 2024; judgment sent to the parties on 23 December 2024.