In a pair of seminal speeches delivered in late 2025, senior figures from the UK judiciary—Sir Peter Roth and CAT Chair Ben Tidswell—issued a warning to the legal and economic professions. The message is clear: the current approach to expert evidence is “unmanageable,” “wasteful,” and in urgent need of a “reset” . For antitrust lawyers, the implications are profound—demand for a cultural shift in how economic arguments are crafted, presented, and managed.
The “Cartel of Misbehaviour”
The most urgent concern radiating from the CAT is the erosion of expert independence. Ben Tidswell described a troubling “mission creep” where the line between the independent expert and the legal team has blurred.
While acknowledging that competition law is a “messy mixture of law and economics” requiring dialogue between lawyers and economists, the Tribunal believes this interaction has gone too far. Experts are increasingly engaging in the wider strategy of cases, tailoring evidence to fit legal arguments, and producing reports that read more like advocacy than independent analysis.
Tidswell went so far as to describe the current environment as a “cartel of misbehaviour”. Because these practices have become embedded across the profession, no party has an incentive to “call it out,” leading to a cycle of mutually assured destruction via partisan reports.
The judicial reaction to this is severe. When an expert strays into advocacy, they “start 10 points down before they even open their mouths” . Sir Peter Roth, reflecting on his years on the bench, noted that judges are increasingly willing to “call out” experts in judgments, attaching little weight to their evidence—a disciplinary measure that experts reportedly welcome as it helps them resist pressure from deep-pocketed clients.
The Volume Crisis: “Unmanageable and Wasteful”
Beyond partiality, the sheer scale of economic evidence has become a logistical nightmare. In the recent Kent v Apple case, written economic evidence alone exceeded two thousand pages (and Sir Peter Roth even questioned the value of Apple’s expert). In Cabo Concepts, the court was deluged with 33 expert reports, making it “impossible to properly digest” the material.
The Tribunal views this “kitchen sink” approach—where experts attempt to cover every conceivable point regardless of relevance—as a major drag on efficiency. It forces judges to wade through “unmanageable volumes” of repetition, obscuring the real issues and adding unnecessarily to costs.
The Evolution of Economic Literacy
This crackdown comes from a Tribunal that is increasingly confident in its own economic literacy. Sir Peter Roth contrasted the modern CAT with the “formalistic” courts of the late 1990s. He recalled a 1999 case where a High Court judge, confronted with econometric analysis, famously admitted, “I have never listened to evidence in any court for an hour and understood so little of it… this is all washing over my head”.
Today, the CAT describes itself as a “sophisticated user” of economic evidence, often sitting with professional economists on the panel. This expertise allows the Tribunal to strip away the obfuscation. As Sir Peter noted, “hot-tubbing” (where experts give evidence concurrently) has become a valuable tool, allowing the court to hear opposing views on specific issues in real-time rather than days apart.
For lawyers, this means the era of baffling the bench with complex econometrics is over. The Tribunal expects an “accessible way into the key issues” and warned that reports failing to prioritize clarity will be “largely sidelined”.
Big Tech and the New Abuse Landscape
This heightened judicial scrutiny is arriving just as the targets of litigation are shifting. Sir Peter Roth observed a significant evolution in the CAT’s docket: while collective actions were expected to be mostly “follow-on” cartel claims, a large number are now “stand-alone” claims for abuse of dominance .
The primary targets are the “Big Tech” giants—Google, Apple, Amazon, Microsoft, and Meta. As Sir Peter wryly noted, “one can hardly claim to be a leading digital platform if one is not a defendant to a collective action before the CAT”.
These cases present unique economic challenges. The alleged abuses often involve “unfair prices” or “unfair trading terms” in markets where the currency is data rather than money, and the competition is for consumer attention (clicks) rather than traditional sales.
However, the judiciary appears undaunted by these novel market structures. Sir Peter recalled his own judgment in Streetmap v Google (2015), which established that self-preferencing could constitute an abuse of dominance even before the term was widely recognized. The view from the bench is that the concept of abuse in competition law is “sufficiently flexible” to evolve with the digital economy. Judges are prepared to recognize that competitive dynamics may look different in the platform economy, but the fundamental objective remains the same: preventing the use of market power to exploit customers.
The New Normal: A Call for Economic Fluency
The CAT has signaled a “tougher approach” through its new Experts Practice Direction. But beyond the procedural rulebook, the speeches reveal a deeper challenge: lawyers can no longer outsource their economic thinking. The “New Normal” requires counsel to be as fluent in finance and economics as they are in the law.
Practitioners must adapt to four key realities:
- Integration, Not Just Instruction: The days of vague instructions are over. Ben Tidswell emphasized that lawyers “want to understand the economic framework” precisely because it is essential for “settling pleadings” and preparing factual evidence. You cannot draft a credible claim if you don’t grasp the underlying economics from day one.
- The Art of “Filtering”: The Tribunal is imposing strict page limits on reports, a move that has faced pushback from lawyers. Tidswell suggests this resistance reflects a failure to recognize “the limits of the expert exercise”. Lawyers must learn enough economics to distinguish the “plausible and workable” from the “purely hypothetical,” ensuring that only relevant economic evidence reaches the judge.
- Financial Literacy is Non-Negotiable: With the rise of collective actions, Sir Peter Roth warned that funding models are becoming “less transparent,” often based on complex multiples rather than simple percentages. Lawyers who cannot deconstruct these financial structures risk conflicts of interest and may struggle to justify settlements to the Tribunal.
- The End of the “Bluff”: The modern Tribunal is economically sophisticated and capable of “hot-tubbing” experts to expose weaknesses in real-time. Lawyers can no longer rely on the complexity of econometrics to mask a weak case. If the judge can spot a flaw in the economic reasoning, counsel must be able to spot it first.
The message from the bench is not just about rules, but culture. The “accepted practice” of extensive lawyer involvement in drafting expert reports is no longer acceptable. As Ben Tidswell concluded, “This is one of those moments where you… ought to stop and think carefully”. For the financial and legal advisors driving these massive cases, the “reset” has officially begun.