Experts must bear in mind their duty to the court at all times
The recent competition case of Kington SARL v Thames Water Utilities Holdings Ltd (Rev1) [2025] EWHC 84 (Ch) raised notable issues around the admissibility of expert evidence.
The judge in this instance rejected an application to rely on expert evidence because he deemed the report an “inappropriate distraction”. The contents of the report were found to be too uncertain and failed to provide evidence that could be relied upon to assist the court.
Table of contents
1. Background
Shower manufacturer, Mira is the owner of UK Patent No.GB 2,466,504 (Patent), which was granted on 10 July 2013 (the filing date and priority date is 24 December 2008). The Patent relates to an electric shower, which has two or more outlets.
Electric showers available on the market at the priority date were limited to only one outlet because of the risk of scalding if the water flow was significantly impaired during operation. Mira’s Patent offered a solution to the issue.
Mira claimed infringement of the Patent by Triton’s ‘DuElec’ range of electric showers, which are marketed in the UK and have two outlets – an overhead shower and a hand shower. Deeley was the key piece of prior art cited by Triton in its validity attack on the Patent.
Both Mira and Triton are UK registered companies, which are well-known and long-established shower manufacturers.
2. Reasons for decision
In rejecting Kington’s request, Mr Justice Trower said the evidence in the report was not reasonably required to resolve the competition law argument at hand.
Rather, the judge said, “much of the draft Murgatroyd Report seems to me to provide background information about how it is said that competition law works, and more theoretical questions such as the economic features of the [funding condition] which are said to be shared with well-established economic theories of harm.”
The judge pointed to CPR 35.1, which says that expert evidence must be restricted to that which is reasonably required to resolve the proceedings.
Referring to British Airways plc v Spencer [2015] EWHC 2477 (Ch), the judge said there were two questions related to the admissibility of such evidence:
- Is the evidence necessary to resolve the proceedings?
- Where evidence is not necessary for that purpose, may it still be of assistance to the court in resolving the issue?
The judge concluded that Murgatroyd’s report met neither requirement. The judge agreed with Philip Moser KC, for the respondent, when he argued that much of the report was inconclusive and speculative.
The justification for describing and developing what is in reality legal analysis or a point of law is that Mr Murgatroyd explains that he is able to look at the problem from an ‘economic perspective’ or that particular conduct can be expected ‘as a matter of economics’ or can be looked at ‘in economic terms’
This is advanced at a relatively high level of abstraction, but when it comes to providing evidence on what might be described as the harder-edged market analysis, such as questions of market description and a dominance assessment on the facts of the present case, there is very little on which the court can rely because of the qualified and tentative terms in which it is expressed.
Judge
In closing, the judge said: “Having regard to the submissions that have been made on the merits of the competition law arguments, I reached the clear conclusion that the draft Murgatroyd Report was either commentary on the law looked at from an economist's perspective or was expressed in such tentative, caveated and incomplete terms that it is not reasonably required to resolve the proceedings. If it were to be admitted, it would indeed be an ‘inappropriate distraction’.”
3. Conclusion
This case is a reminder that it is not incumbent on experts to share their opinion with the court but to provide factual evidence that is of material use in understanding, and reaching a conclusion on, the legal arguments.
It also highlights the time bound nature of many legal proceedings, which means that arguments must not divert from question at hand. The judge made it clear that “the time-critical nature of the current application means that this is a paradigm of a case in which the court must do its best to ensure that the proposed expert evidence really is reasonably required to resolve the proceedings”.
In other words, there is no time to pursue theories when what is required are facts. Experts should always keep their duty to the court front of mind and endeavour to deliver reports that aid the court on a factual basis, rather than sway its opinion.