由於國際間欠缺強而有力的國際協定以有效對抗氣候變遷的衝擊，若干國家遂自行採取單邊政策措施。歐盟的碳排放交易系統即為一例，其方案設定在歐盟碳排放量的限制。然而其他國家卻未必致力於降低溫室氣體排放，相形之下，歐盟所實施的方案可能導致歐盟能源密集產業，相較於其他國家不受類似限制之產業，處於競爭劣勢。為了解決碳洩漏與競爭力的問題，歐盟採取碳均衡系統以利公平競爭，包括實施邊境稅調整之措施。而該等措施是否符合世界貿易組織多邊貿易協定之規範，乃是本文探討之重點。

In the absence of any robust international agreements to combat climate change, some countries and organizations have undertaken unilateral policies and measures. One such example is the European Union’s emissions trading system—a program that sets limits on the quantities of authorized carbon emissions within the EU. This sys-tem places the EU’s energy-intensive industries at a competitive dis-advantage with respect to foreign firms not so constrained. In order to address carbon emissions and competitiveness through climate change policies, the European Union proposed leveling the playing field by implementing the Carbon Equalization System, including border tax adjustments. This paper examines whether those meas-ures are compatible with multilateral trade agreements under the World Trade Organization.