LONDON, Sept. 30, 2026 /PRNewswire/ — Litigators highlight growing tensions between Competition Appeal Tribunal (CAT) demands for greater simplicity and efficiency in economic evidence and the unprecedented complexity of the questions being litigated, according to a new report by a leading provider of economic and financial consulting and expert testimony, Cornerstone Research.

The report, Quantum mechanics: The evolving role of economic evidence in UK competition disputes, draws on interviews with prominent competition litigators from leading law firms—including CMS, Freshfields, Hausfeld, Herbert Smith Freehills Kramer, Linklaters, Quinn Emanuel, and Slaughter and May—alongside Cornerstone Research economists.

It follows the UK Government’s latest consultation on competition redress reform, which closed on 25 September 2026, and the CAT’s Practice Direction 2/2025, which included page limits on some expert reports.

Recent years have been marked both by a series of high-value cases and growing scrutiny of experts by the Tribunal, which has increasingly focused on proportionality and independence, and has challenged what some tribunal members perceive as overly complex or abstract modelling.

Liam Colley, senior vice president and head of Cornerstone Research’s European competition practice, commented on the findings of the report:

“The CAT has been dealing with complex economic issues since its inception in 2003 and has a huge amount of sophistication and judgement. What has changed since the introduction of the class action regime is not the sophistication required, but the sheer scale of what is now at stake in a single case. Claims that would once have been considered exceptional at £1bn have given way to claims of £14bn—an unprecedented figure.

“It would be a mistake to confuse the Tribunal’s pragmatism with an invitation to shy away from doing the complicated economic analysis. The Tribunal is not asking experts to simplify their analysis—in fact, it is being very demanding about what’s going to pass muster. There aren’t shortcuts that experts can take. They have to apply the tools effectively, grounded in the factual matrix, however complex, and explain all that as clearly as they can.”

Key Takeaways

• Economics has moved to the heart of UK competition disputes. Economists increasingly help shape cases from inception and funding through certification, liability, damages, and settlement. The CAT has become an exceptionally sophisticated user of economic evidence but the sheer volume, value, and complexity of collective proceedings are placing growing demands on the Tribunal.
• Judicial scrutiny of economic experts is intensifying. The CAT’s 2025 Practice Direction reinforces expectations around independence, proportionality, and methodology. The Tribunal is increasingly insistent that economic modelling should be firmly anchored in the factual and commercial realities of the case and has been more vocal in criticism of witnesses that it sees as dogmatic or partisan.
• A difficult balance is emerging between sophistication and practicality. Courts require rigorous modelling while also needing evidence that can be understood and applied proportionately. Practitioners question how easily demands for shorter reports, simpler analysis, and narrowing of disagreements can be reconciled with genuinely complex economic questions.
• There is no substitute for high-quality methodologies. Whilst some uncertainty is inherent in economic analysis, robust techniques, credible data, appropriate factual foundations, and transparent and lucid explanation remain critical to producing expert evidence that is useful to the court.
• The expert market itself will need to evolve. Communication, judgement, and the ability to withstand judicial scrutiny increasingly matter alongside technical excellence. Rising demand also creates a need to develop the next generation of testifying economists, broaden the existing talent pool, and improve diversity among experts.

Read the full report: Quantum mechanics: The evolving role of economic evidence in UK competition disputes. 

About Cornerstone Research

Cornerstone Research is at the forefront of economic and financial consulting, delivering the rigorous analytical solutions required to navigate complex disputes. The firm draws from an extensive network of prominent academic and industry experts to support each matter effectively. Pairing a deep understanding of economics and finance with a suite of industry-leading artificial intelligence and machine learning tools, Cornerstone provides clients with a sophisticated, tailored approach. A reputation for innovation, precision, and excellence has defined Cornerstone since 1989. That momentum continues with over 1,000 professionals collaborating across nine offices in the US, UK, and EU.

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SOURCE Cornerstone Research