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Expert Witness Case Study: Is it Possible to be an Expert in Everything?
- Jun 3, 2025
- Latest Journal
The role of an expert witness is critical in modern litigation, particularly in cases involving financial regulatory disputes, fraud, or complex transactions. However, as the scope and complexity of such cases expand, a fundamental question arises: can one individual realistically serve as an expert in multiple aspects of a case? This challenge is particularly evident in both recent and ongoing high-profile, complex trials involving allegations such as market-rigging of interest rate benchmarks and “Cum-Ex” dividend arbitrage trading. Our experience in such cases, across multiple jurisdictions, offers a more nuanced perspective on effectively utilising expertise in the courtroom.
The Complexity of Modern Financial Trials
In these financial “super-trials”, the complexity of the underlying issues can be staggering. Such trials require the court to understand many issues, which may include tax law, cross-border financial transactions, complex trading strategies, financial market infrastructure, trading software and information providers, compliance and regulatory frameworks, forensic accounting and accepted market practice. It is exceedingly rare for an individual expert to possess the depth and breadth of knowledge necessary to comprehensively address such an array of subjects. Even the most qualified professionals typically specialise in only one or two areas.
Traditionally, expert opinions were often provided by academics or generalist consultants, but there is now a growing emphasis on engaging ex-practitioners to offer insights into market practices, which are invaluable to both lawyers and their clients. The emergence of this ‘market practice expert’ is a relatively recent phenomenon and in this series of blog posts we delve deeper into the role, challenges and potential improvements of how such experts might be utilised.
The Limitations of the Single Expert Model
We understand that the standard model of relying on a single expert witness has its strengths, particularly in terms of clarity and accountability. A lone expert is easier to cross-examine and can provide a unified narrative for the court. However, we believe this model also has significant limitations. Taking the “Cum-Ex” trials as an example and concentrating solely on what may be considered as the ‘market practice’ element of the case (which may appear on the face of it to be a narrow definition), expertise would be required on the following topics: dividend arbitrage, derivatives pricing, double tax treaties, equity market infrastructure, stock borrowing and lending, custody chains, middle and back-office procedures, KYC and AML checks, as well as thorough knowledge of specific EU Regulations and the FCA Handbook.
As a result, several issues can arise over the course of an expert’s engagement.
• Overextension of Expertise: Experienced cross-examiners may seek to highlight instances where the expert has ventured beyond their area of expertise or drawn conclusions that lack a solid foundation. Such tactics can weaken the credibility of the expert’s testimony and influence the court’s perception of the reliability of their opinions.
• Practical Constraints: Preparing for cross-examination on a broad range of topics is an enormous burden for a single individual. The risk of being discredited on a tangential issue increases significantly.
• Data Management Challenges: The sheer scale of analysis, such as sifting through data rooms containing millions of documents further strain the capabilities of a single expert to be able to respond to precise, detailed cross-examination.
These challenges underscore the potential for errors or omissions, even with the most diligent experts.
Teamwork in Expert Testimony
Therefore, the question arises: should courts permit or even encourage the use of expert teams to ensure all facets of a case are addressed? Instead of relying on a single individual, a team of specialists can divide responsibilities according to their expertise. For example, in this case:
• a derivatives trader could simplify and add clarity to complex trading strategies;
• an experienced custodian could provide the necessary insight into chains of custody; and
• a compliance specialist could evaluate adherence to local and cross-border regulations
By pooling knowledge, such teams can offer a more robust and reliable testimony. However, we recognise the use of expert teams presents its own challenges, in particular for the courts who must consider questions of admissibility and coordination, thereby requiring effective collaboration and clear delineation of responsibilities.
Court Recognition of the Role of Research and Collaboration
Even when a single expert is engaged, extensive research and collaboration are often required to fill knowledge gaps. Many experts rely on their networks or employ assistants to help navigate data rooms, interpret industry-specific nuances and validate findings. This team effort behind the scenes is rarely visible in court but is crucial to delivering credible testimony.
The reality is that no expert operates in isolation. Whether through formal teams or informal support networks, collaboration is a cornerstone of effective expert testimony. Acknowledging this fact could lead to more transparent and effective practices in the courtroom.
Cross-Examination Challenges
Cross-examination is arguably the most demanding aspect of being an expert witness. When a single individual is tasked with defending their analysis across multiple disciplines, the risk of vulnerability increases. Opposing counsel often aims to exploit any perceived weaknesses in the expert’s knowledge, even if those weaknesses are outside the scope of their primary expertise.
Allowing a team of experts to share this burden could result in more balanced and thorough examinations. Furthermore, as is the case where junior counsel are often given opportunities to partake in narrow cross-examinations during large trials, the new wave of experts could also gain invaluable experience in the witness-box in order to develop and hone their skills.
Conclusion: A Case for Evolving Practices
The complexities of modern financial litigation may require a re-evaluation of how expertise is presented and utilised in court. While the traditional model of a single expert has its merits, it is increasingly clear that this approach may be insufficient for large-scale trials.
The integration of expert teams, combined with transparent collaboration and defined roles, offers a compelling alternative. Such practices not only ensure comprehensive coverage of complex issues but also enhance the credibility and reliability of expert testimony.
Part II
Expert Witness Case Study: Refining the Role of Experts in Complex Litigation
In the second part of the Objectivus review of expert witness practices, we turn our focus to the scope of expert evidence, its timing, and its presentation in court. Whilst financial expert witnesses bring significant value to complex litigation, overly broad mandates and suboptimal presentation can undermine their effectiveness.
The Problem with Overly Broad Mandates
A recurring challenge in financial litigation is the wide scope often given to experts. Unlike medical experts, who are typically tasked with answering narrow, well-defined questions, financial experts are frequently expected to address a sprawling array of issues. This breadth of responsibility can dilute an expert’s focus away from their areas of real expertise, as well as lead to inflated costs, both of which end up complicating the task of assisting the court.
As we mentioned in Part I of this series of articles, the seemingly narrow issue of ‘market practice’ is in fact a very broad definition and requires experts to opine on a wide range of issues, at times extremely specialised.
Providing experts with a narrower scope might lead to several advantages:
• Cost Efficiency: By limiting the questions an expert must address, legal teams can streamline the preparation process for court and reduce fees.
• Enhanced Precision: Experts can devote their full attention to specific areas, providing more reliable and impactful opinions.
• Improved Clarity for the Court: A focused mandate results in clearer, more comprehensible testimony, which is particularly valuable in highly technical cases.
Legal teams and courts should collaborate to ensure that expert instructions are precise, targeted, and aligned with the case’s critical issues.
The Risks of Over-Elaboration
Experts, particularly in complex cases, may feel tempted to over-elaborate their opinions, or stray into factual evidence for which their opinions are not required. This inclination often stems from a desire to appear thorough and authoritative. However, excessive detail can backfire and lead to the following:
• Frustration for the Court: Judges and counsel may struggle to discern the key points amidst a combination of factual evidence and tangential analysis.
• Increased Vulnerability of the Expert: Overly expansive opinions straying from the specific issues provides an opportunity for opposing counsel to find and exploit inconsistencies in cross examination.
• Higher Costs: Preparing and defending overly broad opinions is time-consuming, resource intensive and increasingly expensive.
Experts should focus on delivering concise, relevant, and well-supported analyses. Their role is not to overwhelm but to illuminate the court on issues that truly matter. Furthermore, clients should not be ‘priced out’ of having access to expert opinions therefore the scope of those opinions should be limited as much as possible.
Timing of Expert Evidence: Should It be Presented Earlier?
Traditionally, expert evidence is presented after the court has heard the factual case and witness evidence. While this sequencing aligns with the principle that experts build on established facts, we believe it raises practical questions. By the time expert testimony is introduced, particularly in long, complex trials, both counsel’s and the Judge’s knowledge of the issues will probably already have evolved significantly over the course of the trial. This suggests that the expert evidence could potentially have less impact and the expert reports may also be heavily redacted at this stage of proceedings.
In our opinion there is a compelling case for introducing expert evidence earlier in the proceedings:
• Establishing Context: Experts can help set the stage by explaining complex technical or financial concepts upfront. This foundational knowledge can guide the court’s understanding of the factual evidence, avoiding time-consuming trial time.
• Shaping Legal Arguments: Early expert input allows both sides to refine their submissions in light of the issues highlighted by the experts.
• Reducing Misunderstandings: Delaying expert testimony risks entrenching misinterpretations of technical matters, which can be difficult to undo later.
Of course, presenting expert evidence earlier requires careful planning to avoid prejudicing the court or undermining the factual narrative. Clear procedural guidelines would be essential to ensure fairness.
The Influence of Expert Opinions
Expert evidence often serves as the cornerstone of both parties’ submissions to the court. Once expert reports are submitted, they shape the arguments, strategies, and counterarguments of all involved. This influence underscores the importance of high-quality expert analysis:
• For the Court: Expert opinions guide the judge in interpreting technical evidence and understanding the implications of key facts.
• For Counsel: The opposing side’s expert report often dictates the focus of rebuttal arguments and cross-examination strategies.
Experts must, therefore, be mindful of their dual role: while they serve as impartial advisors to the court, their opinions will inevitably shape the trajectory of the case. The legitimate independence of the expert will always potentially be a matter of contention, something we revisit in later in this series.
Conclusion: Optimising Expert Opinion
To maximise the value of expert witnesses, legal and financial professionals might need to rethink how they define and deploy expertise in litigation. Narrowing the scope of expert instructions, encouraging concise and focused testimony and reconsidering the timing of expert evidence are all steps that could enhance efficiency, clarity, and fairness.
Part III
Expert Witness Case Study: Rethinking
Expertise, Independence, and Testimony
In this third part of our series on financial expert witnesses, we delve into critical questions surrounding the qualifications, independence, and courtroom practices of experts. What constitutes true expertise? How independent can experts really be? And how can the process of presenting expert evidence be refined to better serve the interests of the court?
What Qualifies Someone as an Expert?
In our opinion a central issue in expert testimony is where is the threshold for being considered an expert? In financial litigation, for example, familiarity with industry practices, technical systems, or regulatory frameworks may qualify for expressing expert opinion. However, whilst a strong understanding of the subject matter is an obvious pre-requisite, knowledge gained via academia or senior management positions may not always be comparable to the long-term experience of a market practitioner.
Where ‘normal market practice’ is the central issue for the experts, the process of expert selection is key in order to identify the correct profile of an expert which matches as closely as possible the opinions that both the court and counsel are looking to attain.
Expertise is More Than Technical Knowledge
As we have experienced, being an effective expert witness requires more than technical acumen. Proficiency in presenting complex ideas clearly, handling cross-examination confidently, and adapting explanations to the court’s level of understanding are equally vital.
This distinction between expertise and practical witness proficiency should not be underestimated and an expert’s previous experience as a witness must also be considered. They should be familiar with the demands of legal proceedings and have a clear understanding of their responsibilities within the process. A seasoned expert is typically more adept at report writing, meeting court deadlines, and maintaining their composure under sometimes pressurised cross-examination.
The Challenge of Independence & The Influence of Expert Instructions
In the UK, independence is a fundamental pillar of credible expert testimony but in our opinion true neutrality can be challenging to achieve in practice. Even the most impartial experts may be influenced-consciously or subconsciously-by the party instructing them or the framing of their instructions.
The way an expert’s instructions are framed can significantly influence their opinion. Vague or overly directive instructions risk leading experts toward conclusions that favour the instructing party. This phenomenon underscores the importance of clear, impartial, and narrowly tailored mandates.
Courts and legal teams must be vigilant in ensuring that instructions do not unduly shape expert opinions. Transparency in the framing and delivery of these instructions can help preserve the integrity of the process. The simple fact that in the UK even the supposed independent experts are remunerated by either the Claimant(s) or Defendant(s) will always create a certain level of conflict of interest.
The Single Joint Expert Option
One solution which is gaining traction is the use of a Single Joint Expert (SJE), appointed by both parties or the court. While this approach has the potential to reduce costs and eliminate perceived bias, it also raises concerns:
• Case for the SJE: A single expert eliminates “duelling experts” and simplifies proceedings. Their opinion may carry more weight due to their neutral appointment.
• Case Against the SJE: A jointly appointed expert may face greater scrutiny from both sides, leading to overly cautious or watered-down opinions. Additionally, their selection process can be contentious, particularly in cases involving highly specialised fields.
Striking the right balance between independence and effectiveness remains a key challenge in utilising SJEs and in large trials it is more than likely that the task for one SJE would be insurmountable.
Standardising the Timing of Expert Reports
The timing of expert report submissions varies widely across jurisdictions and cases. Standardising this process could improve efficiency and reduce potential strategic manoeuvring between the experts. For instance, a uniform timeline would ensure that experts on both sides have matching submission deadlines in order to prevent one side from gaining any form of unfair advantage.
The submission of the initial expert reports (and subsequent supplemental reports) is often staggered, allowing the later submissions to effectively rebut the opinions of the primary report. In our experience this can lead to over-elaboration on certain issues and experts straying into almost argumentative mode, structuring their reports in a responsive manner to that first submission.
Without doubt this leads to a significant increase in the time and resource devoted to this ‘rebuttal’ process, whilst at the same time straying into subject matter that would normally be strictly reserved for the Judge to decide upon.
Hot-Tubbing: A Collaborative Approach
“Hot-tubbing,” or the simultaneous examination of multiple experts, is an increasingly popular alternative to traditional cross-examination. In this format, experts from both sides are questioned together, facilitating direct comparisons and clarifications.
Pros:
• Encourages dialogue between experts, allowing them to address each other’s points directly.
• Provides the court with a clearer picture of areas of agreement and disagreement.
• Reduces the adversarial nature of cross-examination, potentially leading to more constructive insights.
Cons:
• Requires careful moderation to prevent discussions from becoming overly technical or contentious.
• May disadvantage less confident experts who struggle to assert their views in a group setting.
When implemented effectively, hot-tubbing can be a powerful tool for distilling complex issues and identifying the true points of contention. It could also provide a significant timesaving for the court, nullifying the need for several experts to be separately cross-examined on predominantly the same subject matter.
Changing Opinions During Trial
In long trials such as the LIBOR rigging case and the “Cum-Ex” dividend related tax reclaims, where factual evidence is presented over a multitude of trial days, it would not be unreasonable for an expert to revise their opinion as new evidence emerges or as they gain a deeper understanding of the case. This can often be viewed as a sign of integrity, as long as the expert must clearly explain the basis for any changes in order to maintain their credibility
However, it can also be perceived as a weakness or inconsistency, particularly during cross-examination. Courts should recognise that evolving opinions, when supported by credible reasoning, are not only legitimate but often necessary in complex cases.
Conclusion: Towards a More Effective Role for Experts
As litigation grows more complex, the role of the expert witness must continue to evolve. Whether through more rigorous qualifications, enhanced independence, or innovative courtroom practices like hot-tubbing, the goal is to ensure that expert evidence remains a reliable and impartial source of assistance to the court.
By addressing the issues of scope, timing, and presentation, legal and financial professionals can better leverage the expertise of witnesses while upholding the principles of fairness and efficiency.
Ultimately, the effectiveness of expert testimony depends not only on the knowledge of the individual but also on the systems and practices that govern its use. In rethinking these processes, courts and litigators have an opportunity to enhance the quality of expert testimony in even the most challenging cases.
Part IV
Expert Witness Opinion: The Objectivus
Approach to Expert Advice
To conclude our series of posts on financial expert witnesses, we turn our attention to the approach taken at Objectivus, a firm ideally positioned to address the complexities and challenges of both expert advice and expert testimony. By leveraging a team-based model, maintaining independence, and offering a breadth of expertise, we ensure our clients receive impartial, precise, and effective support in even the most complex cases.
The Power of the Team Approach
At Objectivus, we recognise that no single individual can master every facet of modern financial litigation. Cases involving allegations such as AML failures or market abuse, alongside expertise regarding accepted market practice or the tax implications of complex financial structures demand a diverse range of skills and insights. That is why we employ a team-based approach, combining the expertise of professionals with specialised knowledge in complementary areas.
l Individual Expertise: Each member of the Objectivus team brings deep, specialised knowledge in most areas of the financial services sectors, including but not limited to, anti-money laundering (AML), market abuse, regulatory compliance, clearing and custody, trading, most (if not all) financial products, and accepted market practices across the industry.
• Collaborative Strength: By working together, our experts provide a holistic analysis that captures the nuances of complex cases while ensuring no critical aspect is overlooked.
• Efficiency and Precision: The collaborative model enables us to divide responsibilities, allowing each expert to focus on their area of strength. This not only enhances the quality of our analysis but also ensures timely delivery of our findings.
Our approach reflects a fundamental truth: in an increasingly complex financial landscape, teamwork is essential to delivering the highest standard of expert evidence.
Independence as a Cornerstone
Independence is not just a principle at Objectivus, it is a practice embedded in everything we do. Our impartiality is achieved through rigorous conflict checks and a commitment to objectivity in all our engagements. This independence ensures that our opinions are guided solely by the evidence and our expertise, free from external influence.
• Conflict Avoidance: We conduct thorough assessments to identify and mitigate any potential conflicts of interest, safeguarding the credibility of our testimony.
• Impartial Analysis: Our experts approach every case with an open mind, basing their conclusions on an objective evaluation of the facts.
This independence is critical to earning the trust of courts, counsel, and other stakeholders, particularly in high-stakes litigation.
A Breadth of Expertise
Objectivus offers a wide-ranging portfolio of expertise, reflecting the diverse challenges faced in financial litigation. Areas of specialisation include:
• AML: Advising on compliance frameworks, identifying red flags, and evaluating the adequacy of AML systems and controls.
• Market Abuse: Investigating allegations of insider trading, market manipulation, and other forms of abuse, supported by a deep understanding of regulatory expectations.
• Complex Structured Products: Breaking down the constituent parts of financial structured products and assessing, for example, their impact on tax-related affairs.
• Market Practices: Providing insights into industry norms and standards, including the evolution of practices over time and their implications for specific cases.
• Regulatory Compliance: Assessing adherence to domestic and international regulations, with particular expertise in cross-border contexts.
• Corporate Governance: Evaluating the adequacy of governance frameworks and the role of management in maintaining compliance and ethical standards.
This comprehensive skill set enables us to address a wide variety of issues, from high-profile fraud cases to intricate regulatory disputes.
The Objectivus Advantage
Our approach ensures that clients benefit from:
• Comprehensive Expertise: A team of specialists with extensive experience in their respective fields.
• Holistic Analysis: A collaborative model that integrates diverse perspectives for a well-rounded view of the case.
• Unwavering Impartiality: Independence that reinforces the credibility and reliability of our testimony.
• Tailored Solutions: Customisable engagement models to suit the unique needs of each case, whether providing individual experts or a coordinated team.
Conclusion: Objectivus as a Partner in Litigation
In an era of increasingly complex financial disputes, the role of expert witnesses has never been more critical. At Objectivus, we embrace this responsibility with a commitment to excellence, independence, and collaboration. By combining individual and collective expertise, we deliver insights that not only clarify the issues at hand but also assist the court in reaching fair and informed decisions.
For legal and financial professionals seeking a trusted partner in expert testimony, we offer a proven model that bridges the gap between technical knowledge, market practitioners and practical courtroom application.
For further information
please contact Simon Bird srb@objectivus.com
or Kevin Thompson kmt@objectivus.com
Objectivus Expert Witness Services
Objectivus Financial Consulting LTD
20 Little Britain
London EC1A 7DH
info@objectivus.com
+44 (0)2034 573 283
www.objectivus.com