歐洲聯盟（EU，簡稱歐盟）毫無疑問是迄今世界上各個主權國家之間所進行之國際間整合最為成功之案例。這個整合不僅僅是區域間的一項成就，同時也是國際間的一個典範。它最初從戰略整合開始，之後從經濟整合出發，逐步邁向其他面向與功能的統合，迄今的進展是在歐盟架構下，一步步地進行超國家（supranational）組織的嘗試。雖然歐盟在國際法的位階只是區域間國際組織（regionalinter-governmentalorganization），但其在國際政治上的定位卻已經儼然具有「歐洲合眾國（United States of Europe）」的重要性，在某些特定議題與領域上，亦具有與美利堅合眾國相抗衡的實力。如此的整合機制促使歐洲成功地建立運作一套讓歐陸能真正地擁有長久和平的體制，這個成就並非僥倖得來的偶然，本文嘗試從國際法的國家論角度，探討歐盟會員國的國家間關係。
European Union isunquestionably the mostsuccessful case of international integration of sovereign States. This integrationis not merely a regionalachievement, italsobecomes the best exmple for the international society. the EU began with strategical cooperation among European State and followed up by the economicintegration, thenitgraduallyintegratefrom all aspects and functions. The ultimate goal for the EU is the attemp to develop a supranational organizatio of States under the EU structure. Although European Union mayberegarded as only a reginalinter-governmentalorganization by traditional international law, its importance and role in the internationlaarenaisperhaps more like a United States of Europe from the perspective of international politics. On severalspecificinternaitonal issues, EU has become as powerful as the United States of America. This mechanism of integration has provided Europe a succesful program in which an eternalpeacecanbeensured. Yet the success of EU is not merely a chain of luck, this article aims to elaborate the relationshipbetween EU membersfrom the perspective of theory of sovereign states under international law.
