The Chartered Institute of Arbitrators (Ciarb) has published a report, titled Party-Appointed Expert Witnesses in International Arbitration: Effectiveness and Best Practice, following a two-year project. Developed by Ciarb's Policy team and four regional working groups, and informed by global practitioner feedback, survey responses from expert witnesses, arbitrators, and external and in-house counsel, and consultations across common and civil law jurisdictions, the report provides non-binding guidance to improve the use, communication and understanding of party-appointed expert witness evidence in international arbitration. It identifies recurring issues in current practice and recommends earlier engagement, clearer communication, and more structured tribunal management, while emphasising that the guidance should be adapted to the circumstances of each case.