Meeting of minds? An assessment of the SCL(S) Protocol on the use of experts’ joint statements in arbitration

Earlier this year, the Singapore Society of Construction Law (“SCL(S)”) published a new Protocol on the use of experts’ joint statements in arbitration (the “Protocol”).¹ It is a welcome and valuable contribution to the ongoing work of developing and standardising best practices in international arbitration. While it was prepared to address expert evidence in the context of construction arbitration, the Protocol is relevant to other types of disputes requiring expert evidence. By consolidating established best practice from common law litigation and transplanting it into the international arbitration context—where no equivalent instrument previously existed—the Protocol performs an important dual function: it provides practitioners working across jurisdictions and legal traditions with a practical common reference point, and it serves as a vehicle for the formation of norms around a process that has lacked consistent standards at an international level.

Two features of the Protocol merit particular attention as practitioners consider the practicalities of adopting it in live arbitrations. First, the Protocol’s Core Principles are expressed as values and best practices rather than prescriptive rules. This reflects a deliberate choice by the drafters suited to the Protocol’s function as guidance, but practitioners will have to bear this in mind when deciding the terms upon which it should be adopted. Second, the restriction on counsel involvement in the joint expert process addressed in Core Principle 3 risks conflating independence of opinion with independence of scope. While it is quite right that independence of expert opinion should be protected, the scope of issues upon which experts should opine is something which counsel may, with some justification, contend that they should be involved in.

Joint expert statements in international arbitration

Joint expert statements are jointly produced by party-appointed experts following an experts’ meeting, recording the issues which have been agreed, those which have not, and the reasons for disagreement. They are particularly valuable in construction disputes, which commonly involve a range of issues requiring expert evidence. According to the recently published CIArb report on party-appointed expert witnesses in international arbitration, 74% of arbitrators, 74% of external counsel and 60% of in-house counsel support establishing joint expert witness reports or statements as a “norm in every arbitration with a view of achieving effectiveness”.² Despite this recognised utility, the practice of preparing joint statements had historically lacked any coherent procedural framework in the international arbitration context, with equivalent guidance existing primarily in the context of litigation before national courts. The Protocol was developed to fill that gap.

The seven core principles

The Protocol is structured as Core Principles, Guidance on how to implement those Core Principles (a similar structure to the Society of Construction Law’s Delay and Disruption Protocol), together with model forms. Parties and tribunals are free to adopt (in whole or in part) and adapt the Protocol according to the needs of the case. Its seven Core Principles may be summarised as follows:

• Core Principle 1: Each expert giving evidence in the joint statement must provide a declaration of competence and independence in the agreed form. The declaration is more than a formality: the tribunal may disregard in whole or in part—or adjust the weight to be placed on—any expert opinion or testimony that fails to comply with its terms;
• Core Principle 2: Expert discussions and associated working materials, including drafts and communications, are to be conducted on a without prejudice basis and may not be used in the proceedings without the parties’ agreement. Unless ordered by the tribunal or agreed by all parties, counsel should not attend expert meetings; if they do attend, their role should be limited strictly to answering questions posed by the experts and advising on matters of law;
• Core Principle 3: Counsel may assist experts in identifying the issues to be addressed in the joint statement and in providing instructions and all relevant and material documents but must not seek to influence the content of the joint statement or participate in its drafting. Counsel may invite experts to consider amendments to a draft only in exceptional circumstances where there are serious concerns that the tribunal may misunderstand or be misled by the joint statement, and any such concerns must be raised with all experts involved;
• Core Principle 4: Unilateral communications between an expert and the tribunal are prohibited, in order to preserve transparency and due process. The tribunal’s broad case management powers in respect of expert evidence are affirmed, including the power to hold conferences with experts outside an evidentiary hearing to assist the tribunal in understanding technical issues;
• Core Principle 5: The timing of expert meetings is flexible and should reflect the nature of the case and the kind of expert evidence required. Early meetings before exchange of individual reports are generally considered sensible in complex matters. The traditional approach of exchanging individual reports first may be more useful in less complex cases. The tribunal is also encouraged to consider the implications of the pleading versus memorial-style procedure on the utility of joint statements;
• Core Principle 6: Each expert should provide full reasons for disagreeing with the other on any particular issue and, where possible, indicate the quantitative effect of that disagreement on the outcome of the case. The Protocol recognises the potential for the use of multiple joint statements in one arbitration, with a final joint statement assisting the tribunal in setting the agenda for expert evidence at the hearing. The model joint statement adopts a Scott Schedule format; and
• Core Principle 7: The tribunal has discretion to direct experts to confer after the hearing and produce supplementary statements—jointly or separately—to address issues arising from the tribunal’s determinations during or following the hearing. This reflects an emerging but previously uncodified practice and is the Protocol’s most genuinely novel provision.

Commentary

Compilation and norm formation

The Protocol is a thoughtful compilation of established best practice transposed into an arbitration-specific instrument, specifically tailored to the expert joint statement. Its core provisions draw on those already found in English Court Civil Procedure Rules (CPR) Part 35 (and Practice Direction), the English Technology and Construction Court (TCC) Guide, the Academy of Experts’ Guidance on Joint Statements, and the CIArb International Arbitration Practice Guideline on Party-Appointed and Tribunal-Appointed Experts. The restrictions on counsel involvement in Core Principle 3 broadly reflect the position in the TCC Guide; the without prejudice default in Core Principle 2 replicates protection that parties in common law arbitrations could already agree to; and the declaration requirements in Core Principle 1 are embedded in both the CIArb Guidelines and the Academy of Experts’ Model Form of Expert Report.

That observation should not, however, be read as minimising the Protocol’s contribution. The existing instruments are either instruments of domestic civil litigation or, even if they do apply to expert evidence in arbitration (e.g. CIArb Guidelines), not specifically aimed at the joint statement process. Transposing familiar principles into an arbitration-specific framework—accompanied by model forms that practitioners can deploy—is useful. The Protocol addresses specific cross-border difficulties that domestic instruments do not reach: the divergence in expectations around counsel involvement between common law and civil law practitioners; the absence of equivalent guidance in major seats of arbitration in APAC, including Singapore and Hong Kong; and the inconsistency in joint statement practice that arises when counsel from different legal traditions operate with fundamentally different assumptions about what is permissible. The Protocol is also the first arbitration-specific instrument to set out a model procedural order and a Scott Schedule format for an expert joint statement.

Equally significant is the Protocol’s norm-formation function. By articulating best practice in a single, authoritative instrument, it contributes to the standardisation of the joint statement process. Even where adopted only as guidance, its Core Principles are likely to influence how counsel, arbitrators, and experts approach the process. That normative contribution is substantial, and is likely to be the Protocol’s most enduring legacy.

The design of the Protocol — A note on adoption

One feature of the Protocol worth noting as practitioners consider adoption is that its Core Principles are expressed as values and best practices rather than as precise prescriptive rules. This is a deliberate choice by the drafters that reflects the nature of the Protocol as guidance rather than mandatory regulation, and it is well suited to the consensual and flexible nature of international arbitration. The Protocol expressly acknowledges that parties are free to adopt it in whole, in part, or as a guideline only.

Practitioners should, however, be attentive to the implications of that flexibility when deciding how to adopt it. The Core Principles leave a degree of discretion to the tribunal and parties in any given case. Parties who adopt the Protocol as binding, without supplementary procedures to resolve points of detail, may find that questions arise in practice that the Protocol does not fully answer: for instance, how to assess whether counsel involvement in a particular exchange has exceeded the permissible minimum, or what consequences should follow if a joint statement does not quantify the effect of a disagreement. Those questions are not unanswerable, but parties may wish to consider addressing key points in advance through a tailored procedural order that uses the Protocol’s model as a starting point.

Used in that way—as an authoritative foundation for bespoke procedural directions rather than as a self-contained binding code—the Protocol is at its most effective. In practice, the majority of parties are likely to find it useful as guidance, and that approach will serve them well.

Core Principle 3 — A point to watch

The most interesting question raised by the Protocol in terms of its future implementation concerns Core Principle 3’s approach to counsel involvement in the joint statement process. The Protocol draws a distinction, rightly, between influencing an expert’s substantive opinion — which is clearly impermissible — and assisting with identifying issues and providing relevant materials, which is permissible. The question worth monitoring is whether, in confining subsequent counsel engagement to exceptional circumstances, Core Principle 3 may in practice make it difficult to maintain a clear distinction between two concepts that are important to keep separate in the context of adversarial proceedings: independence of opinion and independence of scope.

Independence of opinion—the requirement that experts reach their conclusions without being told what to think—is a fundamental and unimpeachable principle. Independence of scope—the proposition that experts determine without counsel engagement which issues to address and within what parameters—is a different matter. It is axiomatic that international arbitration is an adversarial process: expert evidence is adduced to persuade the tribunal, not merely to inform it. An expert’s legitimate function is to give honest, independent evidence—but honest, independent evidence given on the contested issues as framed by the pleadings and the agreed list of issues. The joint statement phase exists within that adversarial framework; its function is to narrow the issues that the parties have placed before the tribunal through their pleadings, not to provide a forum in which experts reconstitute the parameters of the dispute from first principles.

The concern—which is one for observation rather than prediction—is that, without any counsel involvement, an expert could inadvertently agree to a proposition that is technically uncontroversial but legally significant, or accept a framing of an issue that departs from the pleaded case, without any party having authorised that outcome. The “exceptional circumstances” carve-out provides a degree of protection, but it is reactive rather than preventive.

Practitioners adopting Core Principle 3 may wish to supplement it with procedural safeguards: pre-meeting written briefings from counsel on the legal significance of each agenda issue; careful agenda-setting that frames each issue within the parameters of the pleadings; and a written confirmation from the expert that the joint statement is consistent with their genuine opinion (which accords with Core Principle 1). These measures respect the spirit of Core Principle 3—ensuring that the expert’s opinion remains entirely their own—whilst ensuring the expert’s discussion and subsequently the joint statement remain faithful to the scope of the dispute as pleaded by the parties.

Conclusion

The Protocol is a useful and timely addition to the international arbitration practitioner’s toolkit. It fills a gap in international arbitration, consolidates best practice in an accessible and deployable form, and contributes to the ongoing standardisation of good practices in international arbitration—a contribution that is likely to grow as the Protocol is more widely adopted. The points raised above are intended as practical observations for practitioners to bear in mind when considering adoption of the Protocol, and as markers for how application of the Protocol develops in practice. Used thoughtfully—as an authoritative foundation but subject to adaptations to the specific needs of a dispute—the Protocol is a valuable resource and a positive step forward for the management of expert evidence in international arbitration.

¹ SCL(S) Protocol on the use of experts’ joint statements in arbitration, January 2026.
² CIArb report on party-appointed expert witnesses in international arbitration: Effectiveness and best practice, July 2026, p. 74 of PDF.

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