WTO是以規則為導向的體系，會員的行為深受法律邁制之約束，其義務履行彈性空間之大小有無，常繫於該會員的國際法義務內容與拘束力，以及主要對手國對於相關法律義務的認知及實踐。本文以米酒稅調降對美諮商事件為例，檢視WTO相關規定及我國在WTO下所作之承諾，以釐清我國在WTO下的國際法義務及其履行決策之空間。鑒於解釋問題對義釐清之重要性，本文亦探討WTO有權機構，尤其上訴機構，對相關條文的解釋及實踐。此外，本文亦檢視對手國──美針對相關法律義認知及實踐。在釐清我國的國際法義務及對手之認知與實踐後，本文嘗試在國際法義務的基礎上，運用理性選擇的模式，分析我國面對類似事件之提擇選項與決策思維。

The WTO is a rule-based system. The behavior of each WTO member is constrained by the legal regime. The decision-making space in complying with a specific legal obligation under the WTO depends on the contents and binding ‘strength’ of the concerned norms and rules on the one hand, and the legal perceptions and practice of its major opponents on the other. Taking the rice wine tax bargaining against the US as an example, this article firstly examines the relevant WTO norms and rules as well as the commitments Taiwan has undertaken in order to clarify its legal obligations and compliance decision-making space under the WTO. It then discusses the relevant interpretation and practice by competent authorities such as the Appellate Body. Next, it looks at the US’s perceptions and practice in the relevant legal obligations and assesses the decision-making options in the referred case.