Abstract
The use of economic sanctions has increased significantly in recent years and is increasingly intertwined with international investment law. The number of Investor - State Arbitration cases involving economic sanctions has risen sharply, raising a number of difficult legal questions. The tribunal may deem investor's conduct of violating UN sanctions a bar to its jurisdiction or to the admissibility of the claims. The execution of awards may also not proceed smoothly due to sanctions. In addition, there is considerable uncertainty as to whether economic sanctions violate substantive standards of investment protection and treatment, and whether host states can invoke the national security exception in BITs or rely on force majeure, necessity or countermeasures of customary international law to defend against them. In terms of the conflicting values and hierarchy of validity between investment protection and economic sanctions, UN sanction is a matter of international public policy and is more valid than investment treaty obligations, whereas unilateral sanction is not. The accumulation of Investor - State Arbitration cases involving economic sanctions will help clarify the fuzzy relationship between the international investment law system and the economic sanction system. In the absence of international legislation, Investor - State Arbitration can be one of the effective weapons to restrain or counterbalance economic sanctions.