WTO爭端解決機制一向被譽為皇冠上之珍珠，如今上訴機構陷入停擺危機，反而成為皇冠上之荊棘。過去數年來，美國運用WTO所要求之共識，屢次反對上訴機構成員之選任案，尤其是川普政府上台後更加強杯葛之力道。根據爭端解決規則暨程序瞭解書之規定，上訴案件最少由三名成員審理並作成裁決。然而2019年12月10日之後，上訴機構已無法正常運作。長期以來美國對上訴機構提出許多批評，包括系統性、實質性與程序性問題;反之，許多WTO會員則急於補實懸缺，而疏於處理美國關切之事項。根據爭端解決規則暨程序瞭解書第3.2條之規定，爭端解決機制之核心目標在於確保多邊貿易體系之穩定性與可預測性。倘若上訴機構名存實亡，WTO爭端解決機制之運作亦將喪失有效性與可信度。上訴機構無法正常運作，導致以規則為基礎之多邊貿易體系陷入危機。鑒於上訴機構之重要性，本文擬探討危機之根源，回顧美國杯葛之始末與理由，並探討歐盟為了化解上訴機構危機而提出之方案，進行評估。

The dispute settlement system, often considered as the “crown jewel” of the WTO, is in a present crisis and becomes the crown of thorns. Over the past years, the United States through the use of the WTO’s consensus requirements has successfully blocked the launch of a process to select the Appellate Body members. This is carried forward by the Trump administration. With a Settlement of Disputes Understanding (DSU) requirement that appeals be heard by three AB members, with the AB membership down to zero at the present time, the Appellate Body ceased to operate in December 10, 2019. The U.S. Administration makes clear that the U.S. long-standing concerns involve systemic, substantive and procedural issues. However, many WTO members have been pressing for the filling of Appellate Body vacancies first and addressing U.S. concerns over time. Without the Appellate Body, the dispute settlement system loses much of its effectiveness and credibility since the core objective of the system is to “provide security and predictability to the multilateral trading system” as stipulated in Article 3.2 of the DSU. The collapse of the Appellate Body may indicate that the rule-based multilateral trading system will be in peril. In view of the importance of the Appellate Body, this article looks into the reasons for the U.S. blockade and the nature of its concerns. This article also explores the proposals put forward by the European Union and the options available to overcome the impasse.