Arbitrations seated in Thailand are governed principally by the Arbitration Act B.E. 2545 (2002) and, where applicable, the rules of institutions such as the Thailand Arbitration Center (THAC) and the Thai Arbitration Institute (TAI). While these instruments set the core procedural structure, they are not comprehensive. To fill in these procedural gaps, arbitral tribunals often look to the Thai Civil Procedure Code (CPC) and apply its principles when the Arbitration Act or institutional rules are silent. This hybrid system is familiar to local practitioners but can surprise international parties who expect a more self-contained arbitral procedure. Examples of How CPC Principles Are Applied Evidence Management: Section 25 of the Arbitration Act requires equal treatment of the parties and guarantees each side a full opportunity to present its case. At the same time, it grants tribunals broad discretion to conduct proceedings “as it deems appropriate” and expressly suggests that arbitrators may apply the CPC evidence rules where appropriate. In practice, tribunals frequently apply CPC evidence rules when addressing: submission of evidence lists, late or additional evidence, questions of admissibility and relevance, and assessment of witness and expert testimony. Amendments to Pleadings: Because the Arbitration Act and institutional rules provide limited guidance on amending pleadings, tribunals often rely on CPC principles when parties seek to amend a statement of claim or defense. Amendments may be permitted if they are sought in a timely manner, do not unfairly prejudice the opposing party, do not cause undue delay, and do not alter the nature of the dispute. These conditions closely mirror the standards applied by Thai courts under the CPC. Subpoenas and Court Assistance: Arbitral tribunals seated in Thailand generally do not have inherent subpoena powers. Section 33 of the Arbitration Act fills this gap by permitting the tribunal, an individual arbitrator, or a
