Ciarb publishes best-practice guidance on party-appointed experts in international arbitration

On 9 July 2026, the Chartered Institute of Arbitrators (“<span class="news-text_medium">Ciarb</span>”) published its Report on Party-Appointed Expert Witnesses in International Arbitration: Effectiveness and Best Practice (2026). The report provides practical guidance on the use of expert witness evidence in international arbitration for tribunals, counsel, parties and experts.

The report aims to improve the use, communication and understanding of expert evidence in line with contemporary arbitral practice and developing user expectations. It identifies recurrent problems in current practice and brings together best-practice recommendations and commentary.

Research process

The report is the outcome of a two-year project. Its work included a global survey in 2025 of expert witnesses, arbitrators and external and in-house counsel; structured consultations with practitioners from common-law and civil-law jurisdictions; and thematic analysis by Ciarb’s four regional working groups, representing the Americas; Europe and Africa; the Middle East; and Asia Pacific; together with Ciarb’s policy team.

The report considers four principal areas:

• <span class="news-text_medium">Communication:</span> Direct and indirect communication between experts, the tribunal and counsel, including its nature, timing and appropriateness and the tribunal’s role in directing and facilitating it.
• <span class="news-text_medium">Timetabling and engagement:</span> The appointment of experts, the adequacy of the time given to them and the extent to which their input is sought once procedural timetables have been set.
• <span class="news-text_medium">Tribunal understanding:</span> Measures designed to improve a tribunal’s understanding of expert evidence, including expert meetings, agreed methodologies and common data sets, as well as question lists.
• <span class="news-text_medium">Hearings and post-hearing stages:</span> Hearing formats such as cross-examination and expert conferencing, opening presentations by experts and the potential role of private post-hearing contact between the tribunal and experts in the absence of the parties.

A central message of the report is tribunals should adopt a proactive and structured approach to expert evidence. This includes engaging with the reports served, the methodologies used and the underlying data and giving clear procedural directions tailored to the particular requirements of the case.

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<span class="news-text_medium">Source:</span> Ciarb, <a href="https://www.ciarb.org/news-listing/ciarb-publishes-report-on-the-effectiveness-of-expert-witness-evidence-in-arbitration/" target="_blank" class="news-text_link">Ciarb publishes report on the effectiveness of expert witness evidence in arbitration</a>, 9 July 2026.