國際法與國內法交錯的《臺灣關係法》——跨國憲政主義視角的分析

1979年美國與中華人民共和國建交，片面與中華民國（臺灣）斷交。為維持美國與臺灣間的交流，美國國會不顧總統反對，制定《臺灣關係法》。此後，固然臺美之間不存有外交關係，然藉由《臺灣關係法》，使雙方仍維繫斷交前的關係，甚至相當於存在實質的外交關係，故《臺灣關係法》成為美國與臺灣聯繫的重要法律依據。傳統國際法與國內法之間的分野分明，不存有灰色地帶。《臺灣關係法》為美國國內法，因此其形式上的法律效力僅及於美國國境之內。不過，《臺灣關係法》是如何以國內法地位卻跨越美國邊境限制，搭起美國與臺灣之間法律關係的橋樑。本文之問題意識為：《臺灣關係法》如何打破傳統國際法與國內法的界線，以國內法地位達到跨國境之影響力？過去學術研究主要針對《臺灣關係法》之制定過程以及其帶來的國防外交與經濟交流面向，然而鮮少有人從法律面向觀察《臺灣關係法》之貢獻。因此，本文以跨國憲政主義之角度觀察《臺灣關係法》之規範與實踐。本文發現，立法者策略性地在《臺灣關係法》使用不明確的字眼，以緩和國際與國內政治衝突的張力。《臺灣關係法》透過「美國在臺協會」的設置，以民間團體的地位，模糊了公、私部門之間的界線。在其經營之下，即使不存在國際外交關係，也能達到臺美之間聯繫延續的效果。此外，《臺灣關係法》也開創總統與國會共享的外交事務權。《臺灣關係法》「國內法國際法化」的優點為具有直接民主正當性。甚者，相較於國際條約，國內法的修改較簡便，更能適應國家外交政策與政治環境的變遷。因此，在規範設計上，《臺灣關係法》能作為國家對外事務規範框架的典範。不過，面對總統與國會之間的權力鬥爭，由於《臺灣關係法》模棱兩可的文字，因此能透過不同角度解釋與適用《臺灣關係法》，不免導致其無法發揮實際的功能。尤其經過政黨輪替，在不同政黨歧異的對外政策的情形下，《臺灣關係法》難免基於政黨的政治理念，在利益權衡之下，做出相異的外交決策，使得《臺灣關係法》的實踐具有高度不穩定性。最後，雖然《臺灣關係法》並非國際條約，因此臺灣無法經由傳統國際法紛爭解決機制要求美國履行《臺灣關係法》，然而臺灣仍得以透過民間團體藉由國內政治體系的方式實踐《臺灣關係法》的義務。

關鍵字

臺灣關係法；國際法與國內法；跨國憲政主義；臺美關係；美國憲法；總統與國會權力分立

並列摘要

In 1979, the United States established diplomatic relations with the People’s Republic of China and ended them with the Republic of China (Taiwan). To maintain the relationship with Taiwan, regardless of the manifest objection from the Executive, the Congress enacted the Taiwan Relations Act (TRA). Even though there is no diplomatic tie between the U.S. and Taiwan, TRA is designed as the legal basis to connect the tie between them. The distinction between international and domestic law is usually seen as black and white. In theory, TRA as domestic law can only have legal effects within the boundary of the U.S. However, TRA has always had transnational influences and even bridged the connection between the U.S. and Taiwan. The research question is: How does TRA with legal status as domestic law have transnational influences? In this article, I will examine the legal norms and effects of TRA in the perspective of transnational constitutionalism. I discovered that the congressmen strategically utilized ambiguous wordings to alleviate the strains in international and domestic politics. With the foundation of the American Institute in Taiwan, it blurs the division between public and private sectors. It successfully extends the U.S.-Taiwan relations in the absence of diplomatic relations. Moreover, TRA embodies the shared foreign relations authorities between Congress and the Executive. Compared to international law, the “Internationalization of Domestic Law” of TRA has the feature of democratic legitimacy and more feasible procedural process of amendment. Yet, TRA still has its challenges. In the face of struggles between the President and the Congress, the vague wording of TRA can be manipulated and explained in different perspectives. Therefore, with party alterations between varying parties with opposing political interests, TRA may fail to achieve its purposes. Finally, since TRA is not an international treaty, Taiwan could not request the U.S. to fulfill its obligation under international law. However, TRA can still be implemented under the lobbying of nongovernmental organizations via the domestic political mechanism.