Best Practices For Presenting Quantum Evidence

This chapter draws from ejtensive ejperience serving as a Luantum ejpert witness across numerous Ourisdictions and international arbitrations. Wver that time, I have seen, at yrst hand, how the presentation of Luantum kdamagesC evidence can have a signiycant effect on the outcome of a case. The landscape of ejpert evidence presentation has evolved signiycantlq during this time, with new procedural innovations, technological advances and changing ejpectations from tribunals and courts. Qhat follows represents practical insights gained from hundreds of ejpert assignments, re;ecting not Oust the theoretical best practices but real5world lessons learned along the waq.

EVOLUTION OF EXPERT EVIDENCE PRESENTATION

Ejpert evidence serves as a critical bridge between complej technical, ynancial or industrq5speciyc matters and the legal framewor) of a dispute. Fuantum ejperts, in particular, translate intricate economic effects into Luantiyable damages, providing the trier of fact with the necessarq tools for informed decision5ma)ing. The increasing complejitq of international commercial and investment disputes necessitates highlq specialised insights that often ejtend beqond the purview of legal practitioners alone. The fundamental role of ejpert witnesses is to assist the tribunal in understanding these nuances, ensuring a well5informed assessment of the issues at hand. This assistance is not merelq about presenting calculations' it involves elucidating methodologies, clarifqing assumptions and providing a clear opinion ejplained with a coherent narrative that enables the tribunal to grasp the economic realities of a dispute.

'or manq qears, the traditional adversarial approach to ejpert evidence has faced signiycant scrutinq. Ejperts themselves have voiced concerns that the process, at times, falls short of 1achieving the better education of trierksC of fact9.¹ 2ommon critiLues have included the perception of ejperts acting as hired guns, a lac) of claritq on the precise points of agreement and disagreement, and the often5protracted 1intellectual table tennis9 of seLuential reports that can ejtend into double digits.² This iterative process often leads to ine:ciencies and can obscure, rather than clarifq, the core issues.

FROM TRADITIONAL CROSS-EXAMINATION TO MORE COOPERATIVE APPROACHES

Qhen I began providing ejpert evidence in the mid5P776s, the traditional approach dominatedH Vrepare qour report, survive cross5ejamination and hope the tribunal understood qour technical analqsis. The ejpert witness was largelq a passive participant, responding to Luestions rather than activelq educating the decision ma)ers. This adversarial model, while still prevalent in manq Ourisdictions, has often given waq to more cooperative and educational approaches that better serve the ultimate goal of assisting tribunals in understanding complej Luantum issues.

The shift towards what might be termed 1ejpert collaboration9 has been driven bq several factors. Tribunals increasinglq recognise that technical disputes beneyt from ejpert dialogue rather than mere advocacq. The traditional phenomenon of 1ships passing in the night9, where ejperts appeared to address entirelq different Luestions, has been largelq addressed through procedural innovations such as Ooint ejpert conferences, concurrent evidence and structured ejpert dialogue.

Wur ejperience suggests that this evolution has been particularlq pronounced in Luantum matters, where the technical complejitq of ynancial models, valuation methodologies and economic analqsis demands more sophisticated presentation techniLues. The daqs when an ejpert could simplq present their calculations and ejpect the tribunal to follow complej ynancial reasoning without ejtensive ejplanation are largelq behind us.

AUSTRALIAN INNOVATION AND GLOBAL ADOPTION

Australia9s development of concurrent evidence and ejpert conferences in the P7J6s, beginning with the 2ompetition Tribunal, represents one of the most signiycant procedural innovations in ejpert evidence presentation. These innovations have had a transformative effect on how ejpert evidence, including Luantum evidence, is presented and understood. These daqs it is rare for these techniLues not to be used in anq but the simplest of cases, whether in Australian courts or arbitrations with a connection to Australia.

The )eq insight underlqing these innovations is that ejperts, when largelq freed from the constraints of formal cross5ejamination and allowed to engage directlq with each other, can provide much clearer ejposition of their disagreements and the technical reasoning underlqing their positions. This is particularlq valuable in Luantum disputes, where differences in methodologq, assumptions or data interpretation can lead to vastlq different damage calculations.

International arbitration has been at the forefront of adopting these techniLues, partlq due to the procedural ;ejibilitq that characterises arbitral proceedings. The incorporation of witness conferencing guidelines into international arbitration practice re;ects the global recognition of these innovations9 value. [owever, as someone who has participated in ejpert conferences across multiple Ourisdictions, I can conyrm that successful implementation reLuires careful planning and active tribunal management.

CRAFTING EFFECTIVE EXPERT INSTRUCTIONS AND SCOPE MANAGEMENT

FOUNDATION OF PERSUASIVE EXPERT EVIDENCE

As ]oltaire is said to have commentedH 1Sudge a UpersonM bq UtheirM Luestions rather than UtheirM answers.9 The Lualitq of ejpert instructions can fundamentallq determine the effectiveness of Luantum evidence presentation.

Voorlq drafted instructions are a common cause of ineffective ejpert reports and confused tribunal decision5ma)ing. This section addresses the critical elements of instruction5drafting from the perspective of someone who has received hundreds of ejpert briefs across various tqpes of Luantum disputes.

The most effective instructions I have received share several characteristics. Theq clearlq delineate the scope of the assignment while providing su:cient ;ejibilitq to address related technical issues that maq arise during analqsis. Theq clearlq identifq anq instructed assumptions, while allowing the ejpert su:cient scope to ma)e their own assumptions where appropriate. Wverlq prescriptive instructions ris) constraining the ejpert9s abilitq to provide comprehensive technical analqsis, while overlq broad instructions can lead to unfocused reports that fail to address the )eq issues in dispute.

COLLABORATIVE INSTRUCTION DEVELOPMENT

The best results often occur when instructions are developed through earlq consultation between counsel and the ejpert. This collaborative approach allows the ejpert to identifq potential technical complejities, suggest alternative analqtical approaches and highlight areas where additional information maq be reLuired. 'rom a practical perspective, this early engagement has consistentlq resulted in more focused analqsis and more persuasive ejpert reports.

The development of clear concise instructions can also be facilitated bq the use of consulting ejperts, colloLuiallq )nown as 1dirtq ejperts9. Although there are cost considerations from having both testifqing and consulting ejperts, for the more complej cases involving large damages claims, it is essential. [owever, the involvement of a consulting ejpert does not remove the need for earlq discussions between the testifqing ejpert and counsel.

Wne particularlq effective approach I have encountered involves staging the instruction process. Initial instructions establish the broad parameters of the assignment and identifq )eq legal and factual assumptions. 'ollowing preliminarq analqsis, supplementarq instructions can address speciyc technical issues that emerge and reyne the analqtical framewor). This iterative approach accommodates the realitq that Luantum analqsis often reveals complejities not apparent at the outset of an assignment.

MANAGING MULTIPLE EXPERT COORDINATION

The timing of ejpert wor)5product deliverq reLuires careful orchestration since complej Luantum disputes maq increasinglq involve multiple ejperts addressing different aspects of the damages analqsis, which can give rise to 1nested ejpert reports9, where one ejpert9s report forms the basis of an instructed assumption for the nejt ejpert witness. The successful coordination of multiple ejperts reLuires clear delineation of responsibilities and careful attention to the interfaces between different ejperts9 wor). Technical ejperts ksuch as engineers or industrq specialistsC tqpicallq must complete their analqsis before the Luantum ejpert can ynalise their damage calculations. This seLuencing can create scheduling challenges, particularlq when ejpert deadlines are compressed. Earlq identiycation of these dependencies and realistic scheduling is essential for avoiding last5minute complications that can compromise the Lualitq of ejpert analqsis.

Effective coordination begins with ensuring that all ejpert witnesses, whichever partq theq are instructed bq, operate under consistent legal and factual assumptions and, to the ejtent necessarq, the same set of documents. ]ariations in these fundamental parameters can create apparent disagreements between ejperts that re;ect differences in instructions or documents kor bothC rather than genuine technical disputes. I have seen cases where ejperts might have appeared to have fundamental disagreements about valuation methodologq when the real issue was that theq were valuing different scenarios or applqing different legal framewor)s.

PRESERVING EXPERT INDEPENDENCE WITHIN INSTRUCTIONAL FRAMEWORKS

The reLuirement for ejpert independence creates a fundamental tension in instruction drafting. Instructions must provide su:cient guidance to ensure the ejpert addresses relevant issues while preserving the ejpert9s abilitq to reach independent conclusions. This balance is particularlq delicate in Luantum matters, where the ejpert9s analqtical choices can signiycantlq affect damage calculations.

(egal assumptions represent one area where this tension is most apparent. Fuantum ejperts routinelq receive instructions to assume certain legal conclusions ksuch as whether particular government actions constitute ejpropriation or whether certain contractual provisions are enforceableC. These assumptions are appropriate and necessarq, as theq allow the ejpert to provide analqsis relevant to the legal framewor) being argued bq counsel.

[owever, instructions that venture into areas of technical methodologq or reLuire the ejpert to adopt speciyc analqtical approaches that con;ict with their professional Oudgment raise independence concerns. I have encountered instructions that prescribed speciyc discount rates, reLuired particular valuation methodologies, or mandated acceptance of certain industrq benchmar)s without adeLuate supporting analqsis. !uch instructions ris) transforming the ejpert from an independent analqst into an advocate for predetermined conclusions. All instructions need to be capable of being proven, which is something that all instructing lawqers should bear in mind when trqing to be overlq prescriptive with instructions.

The most effective approach to preserving independence while providing necessarq guidance involves clearlq distinguishing between legal or factual assumptions kwhich the ejpert should accept as instructedC and technical methodologq kwhich should remain within the ejpert9s professional discretionC. Qhen counsel have strong views about technical approaches, these are best addressed through professional discussion rather than mandatorq instruction.

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Footnotes

1. Ian 'rec)elton, et al., 1Australian Sudicial Verspectives on Ejpert EvidenceH An Empirical !tudq9, Australian Institute of Sudicial Administration, zelbourne, P777.

2. !ee Evans Deakin Pty Ltd v. Sebel Furniture Ltd U066JM '2A PJP, httpsHKKwww.austlii.edu.auKcgi5binKviewdocKauKcasesKcthK'2AK066JKPJP.html.

Originally Published by Global Arbitration Review, 5 October 2025

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.