What rules must international commercial arbitrators apply to decide according to the law?

The article focuses on the challenges and principles governing arbitral decision-making, particularly the arbitrators' duty to decide according to the law in international commercial arbitration. It highlights the tension between party autonomy and the role of domestic law, noting that while arbitration depends on domestic legal frameworks for enforcement, parties generally have broad freedom to determine applicable rules, and arbitrators are not strictly bound to apply domestic law unless chosen by the parties. The article emphasizes the scarcity of detailed, arbitration-specific rules—especially regarding "twilight issues" that fall outside procedural conduct and merits—and critiques the common but problematic reliance on domestic law for these matters. It advocates for the development of transnational arbitration-specific rules by arbitral institutions to enhance predictability, uniformity, and legitimacy in arbitration, while respecting party autonomy and the unique nature of arbitration as a transnational system of justice.