![Claim No: IL-2025-000064 - [2025] EWHC 2545 (Ch)](https://backend.juristeca.com/files/emisores/logo_O3rEzCI.png){kind=logo}
Claim No: IL-2025-000064 - [2025] EWHC 2545 (Ch)
Fecha: 06-Oct-2025
The burden of establishing that expert evidence is both (i) admissible and (ii) reasonably required (in the sense that it is not just ‘potentially useful’ ) is on the party which seeks permission to a
The burden of establishing that expert evidence is both (i) admissible and (ii) reasonably required (in the sense that it is not just ‘potentially useful’) is on the party which seeks permission to adduce the evidence concerned.
The first matter to consider is whether, looking at each pleaded issue, it is necessary for there to be expert evidence before that issue can be resolved. Expert evidence will be necessary, rather than merely helpful, if the court would not be able to determine the issue without it. In that situation, the expert evidence must be admitted.
If the expert evidence is not necessary, because the court would be able to determine the issue without it, the second matter for the court to consider is whether it would be of assistance to the court in resolving that issue. If it would not even be of assistance to the court, it should refuse permission to admit expert evidence.
If the expert evidence is not necessary, but would be of assistance to the court in resolving the issue, the court must proceed to consider the third matter, which is whether, in the context of the proceedings as a whole, expert evidence on that issue is reasonably required to resolve the proceedings. In such a case, the court has to strike a balance, and assess the proportionality of its admission. In striking that balance, the court should be prepared to take into account a series of disparate factors, including the value of the claim, the effect of a judgment either way on the parties, who is to pay for the commissioning of the evidence on each side, and the delay, if any, which the production of such evidence would entail (particularly delay which might result in the vacation of a trial date).
Complications may arise where a particular piece of expert evidence may go to more than one pleaded issue, or evidence necessary for one issue may need only slight expansion to cover another issue where it would be of assistance, but not necessary.
If evidence is not reasonably required for resolving any particular issue, it is difficult to see how it could ever be reasonably required for resolving the proceedings as a whole.
Before any experts are instructed, clear identification of the issues which they are going to be asked to address is required. Only if the issues are clearly identified is it possible to ascertain whether the experts can give evidence directed to those issues which is (i) admissible and (ii) likely to be of sufficient weight for the cost of preparing their evidence to be proportionate to what is at stake.
- Heading
- Introduction
- Background
- Case management issues
- Disclosure: legal principles
- The first three of these propositions may be distilled from McParland , the fourth from Lombard North Central , and the fifth from PRS v Qatar Airways Group
- Multiple, and overlapping, issues for disclosure should be avoided wherever possible
- Disclosure: Submissions, analysis and conclusions
- I have not yet decided whether this should form one of the issues for disclosure. But if it were to do so, then it would seem to me to eliminate all need for disclosure issue 4 since it makes it unnec
- To the claimants’ knowledge, the defendant could not have replicated Humber elsewhere. Accordingly, the claimants’ case with respect to any Springboard relief (insofar as it is based on the possibilit
- The defendant cannot see that this possibility has been considered by the claimants. The defendant is therefore concerned about the nature of any searches the claimants will have undertaken concerning
- Further, I consider that the claimants place too much emphasis upon the defendant’s own repeated assertions, in contemporaneous documents, that he could (and would) ‘replicate’ Humber (as reproduced a
- Expert evidence: legal principles
- The burden of establishing that expert evidence is both (i) admissible and (ii) reasonably required (in the sense that it is not just ‘potentially useful’ ) is on the party which seeks permission to a
- Barings is authority for propositions (1) and (2); Clifford for proposition (3); The RBS Rights Issue Litigation for proposition (4); British Airways for propositions (5) to (9); and Astex for proposi
- At p. 11, the tribunal described the respondents’ experts’ evidence as “ independent, impressively detailed and completely credible ,” and further that
- Ms Goodman submits that this arbitral decision demonstrates the utility of an expert in this type of assessment as lawyers are obviously ill-equipped to know, and the court will be ill-equipped to adj
- In Henderson & Jones Ltd v Salica Investments Ltd [2025] EWHC 475 (Comm) , Calver J (at paragraph 236) is said to have ordered expert evidence to assist in determining “ (i) whether the allegedly conf
- The decision tells the court nothing about whether or not expert evidence should be ordered in a case governed by the Civil Procedure Rules. That case involved an arbitration. Mr Craig KC rightly says
- Practical utility of confidential information The defendant proposes to rely on the expert evidence of Mr Colin Knight, a qualified trader with over 20 years’ experience in trading strategies. Ms Goodman points out that algorithmic trading was ac
- The claimants have themselves relied on the expert report of Mr Winrow to analyse the coding data extracted from the defendant’s electronic devices, as evidenced by A & O Shearman’s letter of 5 Septem
- It is the claimants who bear the burden of proof in this case, which concerns the nature, and value, of technical descriptions of algorithmic trading strategies and actual code. They are required to p
- Stage in trading strategy development – identifying which stage in the trading strategy development process each piece of ‘confidential information’ (as defined in the particulars of claim) pertained
- The assertion that there are a certain number of stages in the development of a trading strategy at G-Research is the defendant’s own construct , in the sense that it is not said to be a framework ref
- Public domain assessment – assessing whether the ‘confidential information’ was, as a matter of fact, generic and/or widespread industry knowledge within the field of quantitative investment, such tha
- The claimants emphasise that the defendant well knows that the information in issue in this case is not generic and/or widespread industry knowledge. That is precisely why he admits to saying (in an u
- Valuation of confidential information – determining the value of the ‘confidential information’ to a competitor, including with reference to various dates The claimants’ case is that the defendant well knows that Humber is highly valuable: see the co
- Retention of value – Assessing whether, and to what extent, the ‘confidential information’ is likely to retain its value over time, including over a one-year period of garden leave Quite apart from the disproportionate nature of the exercise (not lea
- Practical utility of confidential information – Assessing whether, and to what extent, other businesses (including Citadel Securities) could utilise the ‘confidential information’ in their business ac
- If material at all, this is a question of fact; but, in any event it is extremely difficult to understand how an expert would be able to opine on this matter: it suggests that there would be some reco
- Stage in trading strategy development The claimants submit that the assertion that there are a " number of stages in the development of a trading strategy " is a mere construct. The defendant contends that there is a logical difference be
- Public domain assessment
- The defendant submits that, at most, he referred to Humber at the highest degree of generality, and that the summary to which the court was referred was of minimal value. The parties are, accordingly
- Valuation of confidential information At paragraph 3 of their particulars of claim, the claimants plead that the claim " concerns the defendant's misuse and copying of the claimants' extremely valuable and sensitive confidential informati
- Retention of value Even if the defendant had the requisite knowledge and ability to ‘replicate’ Humber, establishing when Humber is likely to lose its value (through the process of alpha decay) will be the primary consi
- Practical utility of confidential information Conclusions