摘要： 近年来由于对投资保护范围的扩大，投资者与东道国所签订的合同往往亦属于双边投资协定保护的外国投资。若东道国违反合同义务，投资者一方面可以依据合同中的争端解决条款提起“合同之诉”；另一方面，在特定的情况下投资者可能就东道国违反合同义务的行为根据双边投资协定提起“条约之诉”。由于各方对有关双边投资协定中存在的“伞形条款”存在不同理解，使得“合同之诉”与“条约之诉”的竞合问题并未得到最终解决。本文通过对近期ICSID有关案例的分析，辅以对“伞形条款”的历史分析，提出只有当合同违反是因主权行为时，伞形条款方有将合同义务提升到条约义务的效果。

关键词: 双边投资协定 , 伞形条款 , ICSID

Abstract: With the enhanced investment protection，the contract signed by an investor and a state can also be covered by a BIT．When a host country failed to fulfill its contractual obligation，the investor may resort to the dispute resolution clause of the contract itself；or under certain circumstances，bring up a treaty claim based on the BIT．The ambiguity in the interpretation of the umbrella clauses contained in the BITs made the above problem unresolved．By analyzing several cases brought up to the ICSID and the historical development of such umbrella clause，this article suggests that only when a breach of contract is due to the exercise of sovereignty，it could be rendered the so—called parallel effect．

Key words: BIT, Umbrella Clause, ICSID