This article explores the role of international law in relation to the extension of arbitration agreements contained in contracts concluded by States (or State entities) with non-signatory State entities (or States). As contract-based arbitrations involving States or State entities are on the rise, identifying the legal framework governing which parties are covered by the relevant arbitration agreements is of practical importance. The analysis demonstrates that international law forms part of the relevant law, alongside other applicable laws including law of contract, law of the seat and transnational law, concerning the extension of arbitration agreements concluded by States or State entities to non-signatories. Previous analyses have neglected the role of international law by not distinguishing contract-based arbitrations involving private parties from contract-based arbitrations involving States or State entities. Public international law recognises that arbitration agreements can be extended to non-signatories on the basis of implied consent, or abuse of separate legal personality and estoppel. Therefore, foreign investors can rely on international law to extend arbitration agreements to non-signatories in arbitrations conducted under investment contracts concluded by States or State entities, even if the relevant domestic law is agnostic or hostile to this. This has significant legal, and practical, importance.

本文探讨了国际法在扩展国家（或国家实体）与非签署国实体（或国家）签订的合同中所包含的仲裁协议方面的作用。随着涉及国家或国家实体的基于合同的仲裁正在增加，确定相关仲裁协议涵盖哪些当事人的法律框架具有实际重要性。分析表明，国际法与其他适用法律（包括合同法、所在地法和跨国法）一起构成了有关将国家或国家实体缔结的仲裁协议扩展到非签署方的相关法律的一部分。先前的分析忽略了国际法的作用，没有将涉及私人当事人的基于合同的仲裁与涉及国家或国家实体的基于合同的仲裁区分开来。国际公法承认，仲裁协议可以在默示同意或滥用独立法人资格和禁止反言的基础上扩展到非签署方。因此，外国投资者可以依靠国际法将仲裁协议扩展到根据国家或国家实体签订的投资合同进行的仲裁中的非签署方，即使相关国内法对此不可知或持敌对态度。这具有重要的法律和实践意义。国际公法承认，仲裁协议可以在默示同意或滥用独立法人资格和禁止反言的基础上扩展到非签署方。因此，外国投资者可以依靠国际法将仲裁协议扩展到根据国家或国家实体签订的投资合同进行的仲裁中的非签署方，即使相关国内法对此不可知或持敌对态度。这具有重要的法律和实践意义。国际公法承认，仲裁协议可以在默示同意或滥用独立法人资格和禁止反言的基础上扩展到非签署方。因此，外国投资者可以依靠国际法将仲裁协议扩展到根据国家或国家实体签订的投资合同进行的仲裁中的非签署方，即使相关国内法对此不可知或持敌对态度。这具有重要的法律和实践意义。即使相关的国内法对此不可知或持敌意。这具有重要的法律和实践意义。即使相关的国内法对此不可知或持敌意。这具有重要的法律和实践意义。