The value of UK class actions has surged past £151 billion, with more than 750 million class memberships recorded across competition cases, raising concerns about the rapid expansion of mass litigation and the commercial interests driving it.

New research from international law firm CMS reveals that the cumulative value of UK class actions increased by almost £17 billion in 2025.

According to Legal Futures, class memberships in cases before the Competition Appeal Tribunal reached 752 million by the end of 2025, up from 671 million a year earlier.

The figure, more than ten times the UK’s population, reflects individuals being included in multiple actions rather than 752 million separate claimants.

Britain becomes Europe’s class action hotspot

The CMS European Class Action Report 2026 found that the UK accounted for 36% of European class actions filed in 2025, more than twice the share of the next largest jurisdiction, Portugal.

There were 38 new UK actions during the year, while the cumulative value of opt-out claims reached £85.6 billion, overtaking opt-in claims for the first time.

Technology companies have become the leading targets, followed by businesses in energy, financial services and the automotive sector.

CMS identifies Britain’s sophisticated litigation funding market, established claimant law firms and favourable procedural framework as important factors behind this growth.

Who benefits from the boom?

The expansion of opt-out litigation means millions of consumers can be included in proceedings without actively signing up.

These cases are frequently backed by third-party litigation funders that finance proceedings in exchange for a potential financial return.

While supporters argue that this improves access to justice, critics question whether commercial incentives encourage speculative claims and disproportionate litigation costs.

The scale of the sums involved is striking. Across Europe’s highest-risk jurisdictions, the cumulative value of opt-out claims now exceeds €200 billion.

Yet headline claim values reveal little about how much compensation ultimately reaches consumers.

Time for serious scrutiny

The UK’s collective actions regime was intended to improve consumer redress and deter anti-competitive behaviour. But its rapid expansion raises questions about whether those objectives are being achieved.

Greater transparency is needed over funding arrangements, legal costs, settlements and the proportion of damages actually distributed to consumers.

The government’s review of the opt-out collective actions regime offers an opportunity to examine whether the framework strikes the right balance between access to justice and protecting businesses from unmeritorious claims.

With £151 billion in cumulative claims and hundreds of millions of class memberships, the measure of success should not be the size of the litigation market, but whether consumers receive meaningful compensation.