Ciarb publishes report on the effectiveness of expert witness evidence in arbitration
Ciarb has today published its report, Party-Appointed Expert Witnesses in International Arbitration: Effectiveness and Best Practice, following a two-year project that has been shaped by practitioner feedback and informed by themes explored in the 2025 Roebuck Lecture.
The report, which draws on survey insight from expert witnesses, arbitrators, and external and in‑house counsel globally, and consultation with practitioners across disciplines and from both common and civil law traditions, is intended as an advisory reference tool to help improve how expert witness evidence is used, communicated, and understood in international arbitration proceedings.
It offers guidance that tribunals, counsel, parties and expert witnesses may adapt and apply to suit the specific circumstances of each individual case.
Four regional working groups – with representation from Africa, the Americas, the Asia Pacific, Europe and the Middle East – worked with Ciarb’s Policy team to analyse the survey findings, identify the core themes, and provide commentary and recommendations.
The cross-regional working group, led by Co-Chairs Pamela McDonald MCIArb and Michael Tonkin C.Arb FCIArb, Ciarb's Deputy President, includes Abdul-Lateef Jinadu FCIArb, Domingos Fernando Refinetti FCIArb, Igor Corelj MCIArb, and Timothy Cooke FCIArb among its core members.
Pamela said: "This report is a practical, empirically grounded call to improve the use of party-appointed expert evidence. We have identified recurring problems in current practice and consolidated best practice recommendations to promote earlier engagement, clearer communication, and more reliable expert testimony.
The central message is that expert evidence is most effective when tribunals take a more proactive, structured role — focusing issues early, engaging with methodology and data, reading reports as they are served, and giving clear procedural direction — while keeping those recommendations adaptable to the needs of each case."
Michael said: "This report invites all participants in international arbitration to reflect honestly on current practice, to engage with one another’s perspectives, and to consider where behaviours can change to improve the effectiveness of expert evidence overall.”
