Group Litigation: An Overview

Group Actions: Overview

Fundamentally, group actions are about procedures for progressing together several claims giving rise to similar issues. As such, they are capable of being deployed across a wide range of practice areas. Originally, techniques for the management of large numbers of claims were developed in the context of transport disasters and medical product liability. From the mid-1990s onwards, group litigation techniques were brought to bear more widely, particularly in litigation arising out of financial and environmental issues. More recently, data protection has been a growth area for group actions.

The formal Group Litigation Orders (GLOs) made over the last five years give a flavour of activity in this sector. These include claims in relation to:

• the Essure contraceptive device;
• Nigerian oil spills;
• dust from Port Talbot steelworks;
• odour from a Preston processing plant; and
• alleged toxic discharge from a Zambian mine.

In particular, GLOs have been made against almost every vehicle manufacturer in relation to NOx emissions; this is a second wave of claims following the 2018 “Dieselgate” action. The emissions GLOs are being managed together in large “Pan-NOx" case management hearings. Moreover, there is substantial group action activity beyond these formal GLOs, as parties will often adopt court-ordered group structures falling short of a full GLO, as has happened with military noise deafness claims.  

Key Litigation

In this jurisdiction, multiparty litigation has traditionally been “opt-in”, which is to say that a claimant must individually take the decision to opt into the litigation. In 2015, the gates were opened for “opt-out” litigation in the Competition Appeals Tribunal (CAT), allowing a claim to be brought on behalf of an entire class of potential claimants without the need for them to choose to participate. After a slow start, such claims are now flourishing: by the end of 2024, there were over 655 million class members – equivalent to 10.4 class actions for every person in the country. The total value of opt-out claims is now almost on par with that of the opt-ins – and will likely overtake it in the next 12 months.

Nonetheless, “opt-out” litigation in the CAT is still a fledgling field – it was only in December 2024 that judgment was given on the first competition class action to reach trial, Le Patourel v BT Group [2024] CAT 76. A developing theme has been attempts to package claims as competition matters to take advantage of the “opt-out” benefits of the CAT. Such claims will be encouraged by the March 2025 decision in an action against six water companies arising from alleged under-reporting of pollution incidents ([2025] CAT 17). The CAT found that these particular claims were statutorily excluded by the Water Industry Act 1991, but indicated that otherwise it would have permitted them to proceed within the CAT regime.

Another recent landmark CAT decision was the approval of the Merricks v Mastercard class action settlement in May 2025 ([2025] CAT 28). Strikingly, the application had been opposed by the third-party litigation funder, on the grounds that the settlement was too low and was not “just and reasonable” for all stakeholders. However, the CAT confirmed that the “just and reasonable” test set out in Section 49A of the Competition Act 1998 was to be addressed from the perspective of the class members only, saying that it is “fundamental” that the collective proceedings regime should operate for the benefit of class members “and not primarily for the benefit of lawyers and funders”. The funders have since filed a judicial review of the split of the settlement funds between class members and the funder.   

In addition to opt-in and opt-out claims, England and Wales has a “representative action” mechanism set out in CPR 19.8. This requires that the representative and class members have the “same interest”, and that the court exercise its discretion to allow the instant claim to be brought as a representative claim. Historically this has rarely been used, with several recent attempts to bring claims using this mechanism stumbling on the “same interest” test (see Lloyd v Google [2021] UKSC 50 et al). In 2024 the Court of Appeal blessed the use of the representative action mechanism in Commission Recovery Ltd v Marks & Clerk LLP [2024] EWCA Civ 9, a “secret commission” claim, and it was widely hoped that this case would give clarity on key issues affecting the viability of such actions in practice. However, Commission Recovery was settled in late 2024, so the area remains in flux. There have been further chilling breezes from the decision in Wirral Council v Indivior Plc [2025] EWCA Civ 40, where, addressing the suitability of the representative procedure for securities claims, the Court of Appeal emphasised the case management advantages of traditional multiparty proceedings.

As to mass claims generally, the need for claimant lawyers to vet claims sufficiently has been in the spotlight. In Abernethy & Others v Barclays Bank Plc & Others [2025] EWCC 1, the court noted evidence from the defendants that they had received pre-action data subject access requests on behalf of “Darth Vadar”, “Michael Mouse”, “Donald Duck” and “Adolf Hitler”, as well as others whose dates of birth suggested they were “over 100 years old”. The court endorsed the defendants’ concerns as to the accuracy of the claimants’ solicitors’ data and warned against “the metaphorical ‘dumping’ of claims at the doors of the court and of defendants”. Another notable recent decision is Vanquis Bank v TMS Legal [2025] EWHC 1599 (KB), where it was found to be arguable that a claims management company or solicitor is liable for losses caused to defendants by pursuing generic volume litigation which it knows (or ought to know) is not properly arguable.

Technology

Technology is increasingly playing a larger role in the strategies of litigants in this space. Claimant solicitors can use AI to improve engagement with potential claimants and, in doing so, reduce advertising costs. AI can assist in identifying common characteristics and patterns in claims, helping to establish commonalities at the very outset of the claim. AI is also increasingly significant in the administration of a claim.

Defendants, meanwhile, can use tools to see what is being said on social media about their products by their customers. If defendants spot brewing group actions on social media and organise a recall and/or a compensation scheme, they can potentially take the heat and value out of the claims. With quantum neutralised, viability and funding of a group action will be in doubt. At the very least, delay can be achieved – see the decision in Hamon & Others v University College London [2023] EWHC 1812 (KB), where the court was persuaded to stay a GLO application for eight months to allow UCL’s alternative dispute resolution scheme to be explored, in the face of objections by the students bringing the claim.

Funding of course remains central in this area. The Supreme Court’s 2023 “PACCAR” judgment was a setback for litigation funders, holding that agreements which entitle the funder to recover a percentage of any damages recovered are damages-based agreements and are thus prohibited in opt-out competition class actions. In June 2025, the Civil Justice Council recommended reversing PACCAR, but this has not yet been carried into effect.