November 2026 Meeting -CIArb Report on Expert Evidence

Thursday, November 12, 2026 12:00 PM

Expert Evidence in International Arbitration: Are We Getting It Right?

Michael Tonkin, Deputy President of CIArb, and Hon. Barry Leon, Independent Arbitrator and Mediator, and International Arbitration Club of New York member, will lead an interactive discussion examining some of the more challenging questions surrounding party-appointed expert evidence in international arbitration.

Drawing on CIArb’s recently published Report on Party-Appointed Expert Witnesses in International Arbitration: Effectiveness and Best Practice, the discussion will explore the sometimes different perspectives of arbitrators, counsel and experts.

What We Will Discuss

1. Independent expert or party advocate?
   Can the party-appointed expert system genuinely deliver independence?
2. When does instruction become over-instruction?
   Where is the boundary between legitimate assistance and influence?
3. Who owns the expert process?
   The party, counsel, the expert or the tribunal?
4. Are the experts actually qualified?
   What makes someone the right expert?
5. Figures are figures... or are they?
   Why can independent experts reach very different conclusions from the same evidence?
6. Hot-tubbing or cross-examination?
   How should expert evidence best be tested?
7. What is the tribunal’s role?
   Should tribunals intervene earlier and more actively in managing expert evidence?
8. Are we getting it right?
   If we could redesign expert evidence in international arbitration, what would we change?

Speakers

Michael Tonkin

Michael is the incoming President of CIArb for 2027 and currently serves as its Deputy President. He is a Partner with HKA, based in Dubai, and a construction quantum expert and arbitrator. Michael was Co-Chair, with Pamela McDonald, of Ciarb’s recently published Report on Party-Appointed Expert Witnesses in International Arbitration.

Hon. Barry Leon

Barry, a Club member, is an Independent Arbitrator and Mediator. He was the Presiding Judge of the BVI Commercial Court (2015 – 2018), and before that, counsel in international arbitration based in Canada.

Recommended Reading

Those wishing to dip into the Report before the meeting:

• Preamble and Table of Contents: PDF pp. 4–7
• Preface, including Key Findings: PDF pp. 9–17
• Conclusions, Themes 1–4: PDF pp. 135–139

Report: https://www.ciarb.org/media/yzllsqrs/ew-report.pdf