Litigators call for clear evidence

Litigators are highlighting a challenging situation in the UK competition landscape, where the demand for simplicity and efficiency in economic evidence is constantly at odds with the increasing complexity of issues being litigated. A recent report by Cornerstone Research, entitled Quantum mechanics: The evolving role of economic evidence in UK competition disputes, provides insights drawn from interviews with leading competition litigators from top law firms such as CMS, Freshfields, and Herbert Smith Freehills, in addition to economists from Cornerstone Research.

The report arrives in the wake of the UK Government's latest consultation on competition redress reform, which concluded on 25 September 2026, and is timely with the Competition Appeal Tribunal's (CAT) Practice Direction 2/2025 that limits the length of certain expert reports. Over recent years, high-value cases have become more common, leading to increased scrutiny of economic experts by the Tribunal. The CAT's focus has shifted towards proportionality and independence, with tribunal members often challenging what they consider overly complex or abstract economic modelling.

Liam Colley, senior vice president and head of Cornerstone Research's European competition practice, noted that "the CAT has been dealing with complex economic issues since its inception in 2003 and has a huge amount of sophistication and judgement." However, he also remarked on the significant shift in claim values, stating "claims that would once have been considered exceptional at £1bn have given way to claims of £14bn—an unprecedented figure." This reality necessitates a level of diligence and complexity in economic analysis that cannot be overlooked.

Key takeaways from the report indicate that economics is now central to UK competition disputes. Economists increasingly play a pivotal role from case inception to settlement, and the CAT has become a sophisticated user of economic evidence. However, the growing volume and complexity of collective proceedings place escalating demands on the Tribunal.

Moreover, the scrutiny of economic experts is intensifying, as the CAT's 2025 Practice Direction enhances expectations surrounding independence, proportionality, and methodology. There is a growing insistence on economic modelling that is firmly rooted in the factual and commercial realities of each case.

Nevertheless, a delicate balance is emerging between sophistication and practicality, as courts require rigorous modelling while also needing evidence that remains comprehensible and applicable. Practitioners are questioning how demands for shorter reports and simpler analyses can coexist with genuinely complex economic questions.

Ultimately, high-quality methodologies are essential, as some degree of uncertainty is inherent in economic analysis. Robust techniques, credible data, and clear explanations are crucial in producing helpful expert evidence for the court. The expert market itself must adapt as communication skills, judgement, and the ability to withstand judicial scrutiny become imperative alongside technical proficiency. The rising demand for expert testimony also highlights the need to cultivate the next generation of economists and improve diversity within the field.