University of Qom Iranian Journal of International and Comparative Law 2980-9282 3 2 2025 12 01 The Interplay Between Nationality and the Independence and Impartiality of the Arbitrator 4018 10.22091/ijicl.2025.11768.1106 EN Ali Asghar Rahimi University of Qom, Qom, Iran 0009-0009-0525-6236 Seyed Ali Hosseini Balajadeh International Trade Law, Faculty of Law, Allameh Tbatabaie University, Thran, Iran. Journal Article 2024 11 28 Independence and impartiality are essential indicators for qualified arbitrators. However, the criteria for assessing these indicators differ among competent authorities when addressing challenges to arbitrators. One contentious aspect is the nationality of the arbitrators. By examining arbitration rules and issued decisions, a distinction was made between commercial arbitration and investment arbitration. The ICSID rules of arbitration explicitly mention common nationality with the parties as a criterion for challenging an arbitrator. The ICSID practice has also influenced investment arbitration outside of ICSID, given the significant role of nationality throughout investment law. Conversely, in commercial arbitration, the role of nationality is less pronounced, to the extent that the international character of arbitration in various legal systems is determined by the differences in the parties' places of business rather than their nationalities. Consequently, the nationality of arbitrators in commercial arbitration cannot solely serve as a basis for challenging an arbitrator without other supporting factors. https://ijicl.qom.ac.ir/article_4018_93ab0cbadd25e5ac4f28ba9b9ac3b574.pdf