On 18 December 2025, the UK Supreme Court delivered a landmark judgment in Evans v Barclays Bank and others, providing important guidance on the approach the Competition Appeal Tribunal should take when determining whether antitrust class actions should proceed on an opt-out basis.

Background

Since 2015, it has been possible to bring collective proceedings in the Tribunal on an opt-in or opt-out basis. These claims have so far been characterised by allegations covering large classes of claimants and significant damages - a sense of the scale can be seen in the recent Kent v Apple judgment which found liability against Apple on behalf of approximately 36 million class members. While the final damages award is to be determined, it is estimated to exceed £1.3bn.

The Tribunal has an important gatekeeper function in whether these collective actions proceed. One aspect which the Tribunal must consider is whether the proceedings will proceed on an opt-in or opt-out basis. When taking this decision, the Tribunal has broad discretion, but the Tribunal's rules state that it must consider the strength of the claim and whether it is practicable for the proceedings to be brought as opt-in. This appeal focussed on the way in which the Tribunal should consider these key factors.

Evans v Barclays Bank and others

This case stems from pre-Brexit infringement decisions by the European Commission which found that a number of banks had infringed competition law including by exchanging sensitive information and trading plans in relation to Forex spot trading. This claim was brought on behalf of a mixed class of businesses and consumers, alleging the class had suffered loss as a result of these infringements.

The Tribunal's Decision

At first instance, the Tribunal found that the pleaded claim was so weak that it was liable to be struck out. While it gave the proposed class representative (the "PCR") the opportunity to address those concerns, it found that the weakness of the claim was a powerful factor against allowing the proceedings to be brought on an opt-out basis

In reaching its decision, the Tribunal also considered the practicability of bringing the proceedings as opt-in and found that, while the proceedings likely would not be brought on an opt-in basis, that appeared to be because potential class members who had the most to gain did not want to participate.

The Court of Appeal

The Court of Appeal overturned the Tribunal's decision. It considered that, given the PCR had been afforded an opportunity to reformulate his claim, the Tribunal should not have treated its provisional view on the merits as final when deciding that proceedings should not proceed on an opt-out basis. The Court of Appeal also found that the strength of the claim would generally be a neutral factor in deciding whether proceedings should be opt-in or opt-out.

On practicability, the Court of Appeal disagreed with the Tribunal's inferences drawn from the evidence and it regarded the evidence as showing that opt-in proceedings were impracticable. It further set out its own more positive view on the merits of the case, drawing on a European Commission decision published after the Tribunal's judgment had been handed down.

The Court of Appeal also considered the broader aims of the regime, finding that the facilitation of vindication of rights and deterring future wrongdoers are factors which point in favour of opt-out proceedings.

Supreme Court

The Supreme Court disagreed with the Court of Appeal, making four key findings:

1. Strength of the claim – as to the strength of the claim, the Supreme Court found that the Court of Appeal had no proper basis for interfering with the Tribunal's assessment of the strength of the claim nor with the weight that the Tribunal gave to that assessment in choosing between opt-in and opt-out. The Supreme Court was clear that, if a claim is weak, that militates against affording claimants the advantages of an opt-out process.

2. Practicability – the Supreme Court found that the Tribunal had carefully considered the practicability of the proceedings, weighing up the class which was made up of large entities who were likely to be sophisticated potential litigants which were alleged to have suffered large losses and a large number of small entities/ individuals who allegedly suffered loss in smaller amounts. The Tribunal stood back and considered that, while those smaller entities would not be able to bring a claim on an opt-in basis, that was not a factor strong enough to warrant the whole claim being brought on an opt-out basis which was within its margin of discretion.

The Supreme Court noted that this a highly fact-sensitive exercise and one where the Tribunal should have a wide margin of discretion. It found that the Court of Appeal should not have interfered with the Tribunal's careful evaluation here, there was no basis in law to do so.

3. Appropriate factors – the Supreme Court clarified that there is no presumption of predisposition in favour of opt-out over opt-in proceedings. It noted that, while vindicating rights and deterring future wrongdoers are policy goals of the regime, access to justice is something which both claimants and defendants are entitled to. If clearly unmeritorious claims are allowed to proceed on an opt-out basis, that is not due enforcement of the competition rules but – rather - over-enforcement, contrary to the public interest.

4. Hollington v Hewthorn – the rule in Hollington v Hewthorn is a general rule of the common law that findings made by another decision-maker are not admissible as evidence of the facts found before another court. The Tribunal had previously considered that this rule did not apply in the Tribunal. The Supreme Court has found that this rule does apply.

Conclusions

We expect this case will mark a shift in the collective actions landscape, with more claims being certified on an opt-in basis, particularly those which include businesses as part of the class. We anticipate this may influence the attractiveness of future claims for funders and result in a recalibration of the regime, perhaps having the impact of  limiting the regime in the same way that some have argued the Department for Business and Trade's 2025 consultation on the opt-out regime sought to achieve.